commit 38e4cee11e858a642625efcc21163448094ba0b6 · bretton.dev/coves

.env.dev

···

       152
       152
        
       # When false, verifies JWT signature against issuer's JWKS

     

       153
       153
        
       AUTH_SKIP_VERIFY=true

     

       154
       154
        
       

     

       155
       155
       +
       # HS256 Issuers: PDSes allowed to use HS256 (shared secret) authentication

     

       156
       156
       +
       # Must share PDS_JWT_SECRET with Coves instance. External PDSes use ES256 via DID resolution.

     

       157
       157
       +
       # For local dev, allow the local PDS or turn AUTH_SKIP_VERIFY = true

     

       158
       158
       +
       HS256_ISSUERS=http://localhost:3001

     

       159
       159
       +
       

     

       155
       160
        
       # Logging

     

       156
       161
        
       LOG_LEVEL=debug

     

       157
       162
        
       LOG_ENABLED=true

+28

.env.prod.example

···

       27
       27
        
       # PDS_EMAIL_FROM_ADDRESS=noreply@coves.me

     

       28
       28
        
       

     

       29
       29
        
       # =============================================================================

     

       30
       30
       +
       # JWT Authentication

     

       31
       31
       +
       # =============================================================================

     

       32
       32
       +
       # Coves supports two JWT verification methods:

     

       33
       33
       +
       #

     

       34
       34
       +
       # 1. HS256 (shared secret) - For your own PDS

     

       35
       35
       +
       #    - Fast, no network calls needed

     

       36
       36
       +
       #    - Requires shared PDS_JWT_SECRET

     

       37
       37
       +
       #    - Only for PDSes you control

     

       38
       38
       +
       #

     

       39
       39
       +
       # 2. ES256 (DID resolution) - For federated users

     

       40
       40
       +
       #    - Works with any PDS (bsky.social, etc.)

     

       41
       41
       +
       #    - Resolves user's DID document to get public key

     

       42
       42
       +
       #    - No shared secret needed

     

       43
       43
       +
       #

     

       44
       44
       +
       # HS256_ISSUERS: Comma-separated list of PDS URLs allowed to use HS256

     

       45
       45
       +
       # These PDSes MUST share the same PDS_JWT_SECRET with Coves

     

       46
       46
       +
       # Example: HS256_ISSUERS=https://pds.coves.social,https://pds.example.com

     

       47
       47
       +
       HS256_ISSUERS=https://pds.coves.me

     

       48
       48
       +
       

     

       49
       49
       +
       # PLC Directory URL for DID resolution (optional)

     

       50
       50
       +
       # Defaults to https://plc.directory if not set

     

       51
       51
       +
       # PLC_DIRECTORY_URL=https://plc.directory

     

       52
       52
       +
       

     

       53
       53
       +
       # Skip JWT signature verification (DEVELOPMENT ONLY!)

     

       54
       54
       +
       # Set to false in production for proper security

     

       55
       55
       +
       AUTH_SKIP_VERIFY=false

     

       56
       56
       +
       

     

       57
       57
       +
       # =============================================================================

     

       30
       58
        
       # AppView OAuth (for mobile app authentication)

     

       31
       59
        
       # =============================================================================

     

       32
       60
        
       OAUTH_CLIENT_ID=https://coves.social/client-metadata.json

+24 -3

cmd/server/main.go

···

       36
       36
        
       	commentsAPI "Coves/internal/api/handlers/comments"

     

       37
       37
        
       

     

       38
       38
        
       	postgresRepo "Coves/internal/db/postgres"

     

       39
       39
       +
       

     

       40
       40
       +
       	indigoIdentity "github.com/bluesky-social/indigo/atproto/identity"

     

       39
       41
        
       )

     

       40
       42
        
       

     

       41
       43
        
       func main() {

     
···

       142
       144
        
       		log.Println("   Set AUTH_SKIP_VERIFY=false for production")

     

       143
       145
        
       	}

     

       144
       146
        
       

     

       145
       145
       -
       	jwksCacheTTL := 1 * time.Hour // Cache public keys for 1 hour

     

       147
       147
       +
       	// Initialize Indigo directory for DID resolution (used by auth)

     

       148
       148
       +
       	plcURL := os.Getenv("PLC_DIRECTORY_URL")

     

       149
       149
       +
       	if plcURL == "" {

     

       150
       150
       +
       		plcURL = "https://plc.directory"

     

       151
       151
       +
       	}

     

       152
       152
       +
       	indigoDir := &indigoIdentity.BaseDirectory{

     

       153
       153
       +
       		PLCURL:     plcURL,

     

       154
       154
       +
       		HTTPClient: http.Client{Timeout: 10 * time.Second},

     

       155
       155
       +
       	}

     

       156
       156
       +
       

     

       157
       157
       +
       	// Initialize JWT config early to cache HS256_ISSUERS and PDS_JWT_SECRET

     

       158
       158
       +
       	// This avoids reading env vars on every request

     

       159
       159
       +
       	auth.InitJWTConfig()

     

       160
       160
       +
       

     

       161
       161
       +
       	// Create combined key fetcher for both DID and URL issuers

     

       162
       162
       +
       	// - DID issuers (did:plc:, did:web:) → resolved via DID document keys (ES256)

     

       163
       163
       +
       	// - URL issuers → JWKS endpoint (fallback for legacy tokens)

     

       164
       164
       +
       	jwksCacheTTL := 1 * time.Hour

     

       146
       165
        
       	jwksFetcher := auth.NewCachedJWKSFetcher(jwksCacheTTL)

     

       147
       147
       -
       	authMiddleware := middleware.NewAtProtoAuthMiddleware(jwksFetcher, skipVerify)

     

       148
       148
       -
       	log.Println("✅ atProto auth middleware initialized")

     

       166
       166
       +
       	keyFetcher := auth.NewCombinedKeyFetcher(indigoDir, jwksFetcher)

     

       167
       167
       +
       

     

       168
       168
       +
       	authMiddleware := middleware.NewAtProtoAuthMiddleware(keyFetcher, skipVerify)

     

       169
       169
       +
       	log.Println("✅ atProto auth middleware initialized (DID + JWKS key resolution)")

     

       149
       170
        
       

     

       150
       171
        
       	// Initialize repositories and services

     

       151
       172
        
       	userRepo := postgresRepo.NewUserRepository(db)

docker-compose.prod.yml

···

       96
       96
        
             # Cursor encryption for pagination

     

       97
       97
        
             CURSOR_SECRET: ${CURSOR_SECRET}

     

       98
       98
        
       

     

       99
       99
       +
             # PDS JWT secret for verifying HS256 tokens from the PDS

     

       100
       100
       +
             # Must match the PDS_JWT_SECRET configured on the PDS

     

       101
       101
       +
             PDS_JWT_SECRET: ${PDS_JWT_SECRET}

     

       102
       102
       +
             # Whitelist PDS issuer(s) allowed to use HS256 (no kid)

     

       103
       103
       +
             HS256_ISSUERS: ${HS256_ISSUERS}

     

       104
       104
       +
       

     

       99
       105
        
             # Restrict community creation to instance DID only

     

       100
       106
        
             COMMUNITY_CREATORS: did:web:coves.social

     

       101
       107
        
           networks:

+52

internal/atproto/auth/combined_key_fetcher.go

···

       1
       1
       +
       package auth

     

       2
       2
       +
       

     

       3
       3
       +
       import (

     

       4
       4
       +
       	"context"

     

       5
       5
       +
       	"fmt"

     

       6
       6
       +
       	"strings"

     

       7
       7
       +
       

     

       8
       8
       +
       	indigoIdentity "github.com/bluesky-social/indigo/atproto/identity"

     

       9
       9
       +
       )

     

       10
       10
       +
       

     

       11
       11
       +
       // CombinedKeyFetcher handles JWT public key fetching for both:

     

       12
       12
       +
       // - DID issuers (did:plc:, did:web:) → resolves via DID document

     

       13
       13
       +
       // - URL issuers (https://) → fetches via JWKS endpoint (legacy/fallback)

     

       14
       14
       +
       //

     

       15
       15
       +
       // For atproto service authentication, the issuer is typically the user's DID,

     

       16
       16
       +
       // and the signing key is published in their DID document.

     

       17
       17
       +
       type CombinedKeyFetcher struct {

     

       18
       18
       +
       	didFetcher  *DIDKeyFetcher

     

       19
       19
       +
       	jwksFetcher JWKSFetcher

     

       20
       20
       +
       }

     

       21
       21
       +
       

     

       22
       22
       +
       // NewCombinedKeyFetcher creates a key fetcher that supports both DID and URL issuers.

     

       23
       23
       +
       // Parameters:

     

       24
       24
       +
       //   - directory: Indigo's identity directory for DID resolution

     

       25
       25
       +
       //   - jwksFetcher: fallback JWKS fetcher for URL issuers (can be nil if not needed)

     

       26
       26
       +
       func NewCombinedKeyFetcher(directory indigoIdentity.Directory, jwksFetcher JWKSFetcher) *CombinedKeyFetcher {

     

       27
       27
       +
       	return &CombinedKeyFetcher{

     

       28
       28
       +
       		didFetcher:  NewDIDKeyFetcher(directory),

     

       29
       29
       +
       		jwksFetcher: jwksFetcher,

     

       30
       30
       +
       	}

     

       31
       31
       +
       }

     

       32
       32
       +
       

     

       33
       33
       +
       // FetchPublicKey fetches the public key for verifying a JWT.

     

       34
       34
       +
       // Routes to the appropriate fetcher based on issuer format:

     

       35
       35
       +
       // - DID (did:plc:, did:web:) → DIDKeyFetcher

     

       36
       36
       +
       // - URL (https://) → JWKSFetcher

     

       37
       37
       +
       func (f *CombinedKeyFetcher) FetchPublicKey(ctx context.Context, issuer, token string) (interface{}, error) {

     

       38
       38
       +
       	// Check if issuer is a DID

     

       39
       39
       +
       	if strings.HasPrefix(issuer, "did:") {

     

       40
       40
       +
       		return f.didFetcher.FetchPublicKey(ctx, issuer, token)

     

       41
       41
       +
       	}

     

       42
       42
       +
       

     

       43
       43
       +
       	// Check if issuer is a URL (https:// or http:// in dev)

     

       44
       44
       +
       	if strings.HasPrefix(issuer, "https://") || strings.HasPrefix(issuer, "http://") {

     

       45
       45
       +
       		if f.jwksFetcher == nil {

     

       46
       46
       +
       			return nil, fmt.Errorf("URL issuer %s requires JWKS fetcher, but none configured", issuer)

     

       47
       47
       +
       		}

     

       48
       48
       +
       		return f.jwksFetcher.FetchPublicKey(ctx, issuer, token)

     

       49
       49
       +
       	}

     

       50
       50
       +
       

     

       51
       51
       +
       	return nil, fmt.Errorf("unsupported issuer format: %s (expected DID or URL)", issuer)

     

       52
       52
       +
       }

+116

internal/atproto/auth/did_key_fetcher.go

···

       1
       1
       +
       package auth

     

       2
       2
       +
       

     

       3
       3
       +
       import (

     

       4
       4
       +
       	"context"

     

       5
       5
       +
       	"crypto/ecdsa"

     

       6
       6
       +
       	"crypto/elliptic"

     

       7
       7
       +
       	"encoding/base64"

     

       8
       8
       +
       	"fmt"

     

       9
       9
       +
       	"math/big"

     

       10
       10
       +
       	"strings"

     

       11
       11
       +
       

     

       12
       12
       +
       	"github.com/bluesky-social/indigo/atproto/atcrypto"

     

       13
       13
       +
       	indigoIdentity "github.com/bluesky-social/indigo/atproto/identity"

     

       14
       14
       +
       	"github.com/bluesky-social/indigo/atproto/syntax"

     

       15
       15
       +
       )

     

       16
       16
       +
       

     

       17
       17
       +
       // DIDKeyFetcher fetches public keys from DID documents for JWT verification.

     

       18
       18
       +
       // This is the primary method for atproto service authentication, where:

     

       19
       19
       +
       // - The JWT issuer is the user's DID (e.g., did:plc:abc123)

     

       20
       20
       +
       // - The signing key is published in the user's DID document

     

       21
       21
       +
       // - Verification happens by resolving the DID and checking the signature

     

       22
       22
       +
       type DIDKeyFetcher struct {

     

       23
       23
       +
       	directory indigoIdentity.Directory

     

       24
       24
       +
       }

     

       25
       25
       +
       

     

       26
       26
       +
       // NewDIDKeyFetcher creates a new DID-based key fetcher.

     

       27
       27
       +
       func NewDIDKeyFetcher(directory indigoIdentity.Directory) *DIDKeyFetcher {

     

       28
       28
       +
       	return &DIDKeyFetcher{

     

       29
       29
       +
       		directory: directory,

     

       30
       30
       +
       	}

     

       31
       31
       +
       }

     

       32
       32
       +
       

     

       33
       33
       +
       // FetchPublicKey fetches the public key for verifying a JWT from the issuer's DID document.

     

       34
       34
       +
       // For DID issuers (did:plc: or did:web:), resolves the DID and extracts the signing key.

     

       35
       35
       +
       // Returns an *ecdsa.PublicKey suitable for use with jwt-go.

     

       36
       36
       +
       func (f *DIDKeyFetcher) FetchPublicKey(ctx context.Context, issuer, token string) (interface{}, error) {

     

       37
       37
       +
       	// Only handle DID issuers

     

       38
       38
       +
       	if !strings.HasPrefix(issuer, "did:") {

     

       39
       39
       +
       		return nil, fmt.Errorf("DIDKeyFetcher only handles DID issuers, got: %s", issuer)

     

       40
       40
       +
       	}

     

       41
       41
       +
       

     

       42
       42
       +
       	// Parse the DID

     

       43
       43
       +
       	did, err := syntax.ParseDID(issuer)

     

       44
       44
       +
       	if err != nil {

     

       45
       45
       +
       		return nil, fmt.Errorf("invalid DID format: %w", err)

     

       46
       46
       +
       	}

     

       47
       47
       +
       

     

       48
       48
       +
       	// Resolve the DID to get the identity (includes public keys)

     

       49
       49
       +
       	ident, err := f.directory.LookupDID(ctx, did)

     

       50
       50
       +
       	if err != nil {

     

       51
       51
       +
       		return nil, fmt.Errorf("failed to resolve DID %s: %w", issuer, err)

     

       52
       52
       +
       	}

     

       53
       53
       +
       

     

       54
       54
       +
       	// Get the atproto signing key from the DID document

     

       55
       55
       +
       	pubKey, err := ident.PublicKey()

     

       56
       56
       +
       	if err != nil {

     

       57
       57
       +
       		return nil, fmt.Errorf("failed to get public key from DID document: %w", err)

     

       58
       58
       +
       	}

     

       59
       59
       +
       

     

       60
       60
       +
       	// Convert to JWK format to extract coordinates

     

       61
       61
       +
       	jwk, err := pubKey.JWK()

     

       62
       62
       +
       	if err != nil {

     

       63
       63
       +
       		return nil, fmt.Errorf("failed to convert public key to JWK: %w", err)

     

       64
       64
       +
       	}

     

       65
       65
       +
       

     

       66
       66
       +
       	// Convert atcrypto JWK to Go ecdsa.PublicKey

     

       67
       67
       +
       	return atcryptoJWKToECDSA(jwk)

     

       68
       68
       +
       }

     

       69
       69
       +
       

     

       70
       70
       +
       // atcryptoJWKToECDSA converts an atcrypto.JWK to a Go ecdsa.PublicKey

     

       71
       71
       +
       func atcryptoJWKToECDSA(jwk *atcrypto.JWK) (*ecdsa.PublicKey, error) {

     

       72
       72
       +
       	if jwk.KeyType != "EC" {

     

       73
       73
       +
       		return nil, fmt.Errorf("unsupported JWK key type: %s (expected EC)", jwk.KeyType)

     

       74
       74
       +
       	}

     

       75
       75
       +
       

     

       76
       76
       +
       	// Decode X and Y coordinates (base64url, no padding)

     

       77
       77
       +
       	xBytes, err := base64.RawURLEncoding.DecodeString(jwk.X)

     

       78
       78
       +
       	if err != nil {

     

       79
       79
       +
       		return nil, fmt.Errorf("invalid JWK X coordinate encoding: %w", err)

     

       80
       80
       +
       	}

     

       81
       81
       +
       	yBytes, err := base64.RawURLEncoding.DecodeString(jwk.Y)

     

       82
       82
       +
       	if err != nil {

     

       83
       83
       +
       		return nil, fmt.Errorf("invalid JWK Y coordinate encoding: %w", err)

     

       84
       84
       +
       	}

     

       85
       85
       +
       

     

       86
       86
       +
       	var ecCurve elliptic.Curve

     

       87
       87
       +
       	switch jwk.Curve {

     

       88
       88
       +
       	case "P-256":

     

       89
       89
       +
       		ecCurve = elliptic.P256()

     

       90
       90
       +
       	case "P-384":

     

       91
       91
       +
       		ecCurve = elliptic.P384()

     

       92
       92
       +
       	case "P-521":

     

       93
       93
       +
       		ecCurve = elliptic.P521()

     

       94
       94
       +
       	case "secp256k1":

     

       95
       95
       +
       		// secp256k1 (K-256) is used by some atproto implementations

     

       96
       96
       +
       		// Go's standard library doesn't include secp256k1, but we can still

     

       97
       97
       +
       		// construct the key - jwt-go may not support it directly

     

       98
       98
       +
       		return nil, fmt.Errorf("secp256k1 curve requires special handling for JWT verification")

     

       99
       99
       +
       	default:

     

       100
       100
       +
       		return nil, fmt.Errorf("unsupported JWK curve: %s", jwk.Curve)

     

       101
       101
       +
       	}

     

       102
       102
       +
       

     

       103
       103
       +
       	// Create the public key

     

       104
       104
       +
       	pubKey := &ecdsa.PublicKey{

     

       105
       105
       +
       		Curve: ecCurve,

     

       106
       106
       +
       		X:     new(big.Int).SetBytes(xBytes),

     

       107
       107
       +
       		Y:     new(big.Int).SetBytes(yBytes),

     

       108
       108
       +
       	}

     

       109
       109
       +
       

     

       110
       110
       +
       	// Validate point is on curve

     

       111
       111
       +
       	if !ecCurve.IsOnCurve(pubKey.X, pubKey.Y) {

     

       112
       112
       +
       		return nil, fmt.Errorf("invalid public key: point not on curve")

     

       113
       113
       +
       	}

     

       114
       114
       +
       

     

       115
       115
       +
       	return pubKey, nil

     

       116
       116
       +
       }

+209 -29

internal/atproto/auth/jwt.go

···

       12
       12
        
       	"net/url"

     

       13
       13
        
       	"os"

     

       14
       14
        
       	"strings"

     

       15
       15
       +
       	"sync"

     

       15
       16
        
       	"time"

     

       16
       17
        
       

     

       17
       18
        
       	"github.com/golang-jwt/jwt/v5"

     

       18
       19
        
       )

     

       19
       20
        
       

     

       21
       21
       +
       // jwtConfig holds cached JWT configuration to avoid reading env vars on every request

     

       22
       22
       +
       type jwtConfig struct {

     

       23
       23
       +
       	hs256Issuers map[string]struct{} // Set of whitelisted HS256 issuers

     

       24
       24
       +
       	pdsJWTSecret []byte              // Cached PDS_JWT_SECRET

     

       25
       25
       +
       	isDevEnv     bool                // Cached IS_DEV_ENV

     

       26
       26
       +
       }

     

       27
       27
       +
       

     

       28
       28
       +
       var (

     

       29
       29
       +
       	cachedConfig *jwtConfig

     

       30
       30
       +
       	configOnce   sync.Once

     

       31
       31
       +
       )

     

       32
       32
       +
       

     

       33
       33
       +
       // InitJWTConfig initializes the JWT configuration from environment variables.

     

       34
       34
       +
       // This should be called once at startup. If not called explicitly, it will be

     

       35
       35
       +
       // initialized lazily on first use.

     

       36
       36
       +
       func InitJWTConfig() {

     

       37
       37
       +
       	configOnce.Do(func() {

     

       38
       38
       +
       		cachedConfig = &jwtConfig{

     

       39
       39
       +
       			hs256Issuers: make(map[string]struct{}),

     

       40
       40
       +
       			isDevEnv:     os.Getenv("IS_DEV_ENV") == "true",

     

       41
       41
       +
       		}

     

       42
       42
       +
       

     

       43
       43
       +
       		// Parse HS256_ISSUERS into a set for O(1) lookup

     

       44
       44
       +
       		if issuers := os.Getenv("HS256_ISSUERS"); issuers != "" {

     

       45
       45
       +
       			for _, issuer := range strings.Split(issuers, ",") {

     

       46
       46
       +
       				issuer = strings.TrimSpace(issuer)

     

       47
       47
       +
       				if issuer != "" {

     

       48
       48
       +
       					cachedConfig.hs256Issuers[issuer] = struct{}{}

     

       49
       49
       +
       				}

     

       50
       50
       +
       			}

     

       51
       51
       +
       		}

     

       52
       52
       +
       

     

       53
       53
       +
       		// Cache PDS_JWT_SECRET

     

       54
       54
       +
       		if secret := os.Getenv("PDS_JWT_SECRET"); secret != "" {

     

       55
       55
       +
       			cachedConfig.pdsJWTSecret = []byte(secret)

     

       56
       56
       +
       		}

     

       57
       57
       +
       	})

     

       58
       58
       +
       }

     

       59
       59
       +
       

     

       60
       60
       +
       // getConfig returns the cached config, initializing if needed

     

       61
       61
       +
       func getConfig() *jwtConfig {

     

       62
       62
       +
       	InitJWTConfig()

     

       63
       63
       +
       	return cachedConfig

     

       64
       64
       +
       }

     

       65
       65
       +
       

     

       66
       66
       +
       // ResetJWTConfigForTesting resets the cached config to allow re-initialization.

     

       67
       67
       +
       // This should ONLY be used in tests.

     

       68
       68
       +
       func ResetJWTConfigForTesting() {

     

       69
       69
       +
       	cachedConfig = nil

     

       70
       70
       +
       	configOnce = sync.Once{}

     

       71
       71
       +
       }

     

       72
       72
       +
       

     

       73
       73
       +
       // Algorithm constants for JWT signing methods

     

       74
       74
       +
       const (

     

       75
       75
       +
       	AlgorithmHS256 = "HS256"

     

       76
       76
       +
       	AlgorithmRS256 = "RS256"

     

       77
       77
       +
       	AlgorithmES256 = "ES256"

     

       78
       78
       +
       )

     

       79
       79
       +
       

     

       80
       80
       +
       // JWTHeader represents the parsed JWT header

     

       81
       81
       +
       type JWTHeader struct {

     

       82
       82
       +
       	Alg string `json:"alg"`

     

       83
       83
       +
       	Kid string `json:"kid"`

     

       84
       84
       +
       	Typ string `json:"typ,omitempty"`

     

       85
       85
       +
       }

     

       86
       86
       +
       

     

       20
       87
        
       // Claims represents the standard JWT claims we care about

     

       21
       88
        
       type Claims struct {

     

       22
       89
        
       	jwt.RegisteredClaims

     

       23
       90
        
       	Scope string `json:"scope,omitempty"`

     

       24
       91
        
       }

     

       25
       92
        
       

     

       93
       93
       +
       // stripBearerPrefix removes the "Bearer " prefix from a token string

     

       94
       94
       +
       func stripBearerPrefix(tokenString string) string {

     

       95
       95
       +
       	tokenString = strings.TrimPrefix(tokenString, "Bearer ")

     

       96
       96
       +
       	return strings.TrimSpace(tokenString)

     

       97
       97
       +
       }

     

       98
       98
       +
       

     

       99
       99
       +
       // ParseJWTHeader extracts and parses the JWT header from a token string

     

       100
       100
       +
       // This is a reusable function for getting algorithm and key ID information

     

       101
       101
       +
       func ParseJWTHeader(tokenString string) (*JWTHeader, error) {

     

       102
       102
       +
       	tokenString = stripBearerPrefix(tokenString)

     

       103
       103
       +
       

     

       104
       104
       +
       	parts := strings.Split(tokenString, ".")

     

       105
       105
       +
       	if len(parts) != 3 {

     

       106
       106
       +
       		return nil, fmt.Errorf("invalid JWT format: expected 3 parts, got %d", len(parts))

     

       107
       107
       +
       	}

     

       108
       108
       +
       

     

       109
       109
       +
       	headerBytes, err := base64.RawURLEncoding.DecodeString(parts[0])

     

       110
       110
       +
       	if err != nil {

     

       111
       111
       +
       		return nil, fmt.Errorf("failed to decode JWT header: %w", err)

     

       112
       112
       +
       	}

     

       113
       113
       +
       

     

       114
       114
       +
       	var header JWTHeader

     

       115
       115
       +
       	if err := json.Unmarshal(headerBytes, &header); err != nil {

     

       116
       116
       +
       		return nil, fmt.Errorf("failed to parse JWT header: %w", err)

     

       117
       117
       +
       	}

     

       118
       118
       +
       

     

       119
       119
       +
       	return &header, nil

     

       120
       120
       +
       }

     

       121
       121
       +
       

     

       122
       122
       +
       // shouldUseHS256 determines if a token should use HS256 verification

     

       123
       123
       +
       // This prevents algorithm confusion attacks by using multiple signals:

     

       124
       124
       +
       // 1. If the token has a `kid` (key ID), it MUST use asymmetric verification

     

       125
       125
       +
       // 2. If no `kid`, only allow HS256 from whitelisted issuers (your own PDS)

     

       126
       126
       +
       //

     

       127
       127
       +
       // This approach supports open federation because:

     

       128
       128
       +
       // - External PDSes publish keys via JWKS and include `kid` in their tokens

     

       129
       129
       +
       // - Only your own PDS (which shares PDS_JWT_SECRET) uses HS256 without `kid`

     

       130
       130
       +
       func shouldUseHS256(header *JWTHeader, issuer string) bool {

     

       131
       131
       +
       	// If token has a key ID, it MUST use asymmetric verification

     

       132
       132
       +
       	// This is the primary defense against algorithm confusion attacks

     

       133
       133
       +
       	if header.Kid != "" {

     

       134
       134
       +
       		return false

     

       135
       135
       +
       	}

     

       136
       136
       +
       

     

       137
       137
       +
       	// No kid - check if issuer is whitelisted for HS256

     

       138
       138
       +
       	// This should only include your own PDS URL(s)

     

       139
       139
       +
       	return isHS256IssuerWhitelisted(issuer)

     

       140
       140
       +
       }

     

       141
       141
       +
       

     

       142
       142
       +
       // isHS256IssuerWhitelisted checks if the issuer is in the HS256 whitelist

     

       143
       143
       +
       // Only your own PDS should be in this list - external PDSes should use JWKS

     

       144
       144
       +
       func isHS256IssuerWhitelisted(issuer string) bool {

     

       145
       145
       +
       	cfg := getConfig()

     

       146
       146
       +
       	_, whitelisted := cfg.hs256Issuers[issuer]

     

       147
       147
       +
       	return whitelisted

     

       148
       148
       +
       }

     

       149
       149
       +
       

     

       26
       150
        
       // ParseJWT parses a JWT token without verification (Phase 1)

     

       27
       151
        
       // Returns the claims if the token is valid JSON and has required fields

     

       28
       152
        
       func ParseJWT(tokenString string) (*Claims, error) {

     

       29
       153
        
       	// Remove "Bearer " prefix if present

     

       30
       30
       -
       	tokenString = strings.TrimPrefix(tokenString, "Bearer ")

     

       31
       31
       -
       	tokenString = strings.TrimSpace(tokenString)

     

       154
       154
       +
       	tokenString = stripBearerPrefix(tokenString)

     

       32
       155
        
       

     

       33
       156
        
       	// Parse without verification first to extract claims

     

       34
       157
        
       	parser := jwt.NewParser(jwt.WithoutClaimsValidation())

     
···

       67
       190
        
       

     

       68
       191
        
       // VerifyJWT verifies a JWT token's signature and claims (Phase 2)

     

       69
       192
        
       // Fetches the public key from the issuer's JWKS endpoint and validates the signature

     

       193
       193
       +
       // For HS256 tokens from whitelisted issuers, uses the shared PDS_JWT_SECRET

     

       194
       194
       +
       //

     

       195
       195
       +
       // SECURITY: Algorithm is determined by the issuer whitelist, NOT the token header,

     

       196
       196
       +
       // to prevent algorithm confusion attacks where an attacker could re-sign a token

     

       197
       197
       +
       // with HS256 using a public key as the secret.

     

       70
       198
        
       func VerifyJWT(ctx context.Context, tokenString string, keyFetcher JWKSFetcher) (*Claims, error) {

     

       71
       71
       -
       	// First parse to get the issuer

     

       199
       199
       +
       	// Strip Bearer prefix once at the start

     

       200
       200
       +
       	tokenString = stripBearerPrefix(tokenString)

     

       201
       201
       +
       

     

       202
       202
       +
       	// First parse to get the issuer (needed to determine expected algorithm)

     

       72
       203
        
       	claims, err := ParseJWT(tokenString)

     

       73
       204
        
       	if err != nil {

     

       74
       205
        
       		return nil, err

     

       75
       206
        
       	}

     

       76
       207
        
       

     

       77
       77
       -
       	// Fetch the public key from the issuer

     

       78
       78
       -
       	publicKey, err := keyFetcher.FetchPublicKey(ctx, claims.Issuer, tokenString)

     

       208
       208
       +
       	// Parse header to get the claimed algorithm (for validation)

     

       209
       209
       +
       	header, err := ParseJWTHeader(tokenString)

     

       210
       210
       +
       	if err != nil {

     

       211
       211
       +
       		return nil, err

     

       212
       212
       +
       	}

     

       213
       213
       +
       

     

       214
       214
       +
       	// SECURITY: Determine verification method based on token characteristics

     

       215
       215
       +
       	// 1. Tokens with `kid` MUST use asymmetric verification (supports federation)

     

       216
       216
       +
       	// 2. Tokens without `kid` can use HS256 only from whitelisted issuers (your own PDS)

     

       217
       217
       +
       	useHS256 := shouldUseHS256(header, claims.Issuer)

     

       218
       218
       +
       

     

       219
       219
       +
       	if useHS256 {

     

       220
       220
       +
       		// Verify token actually claims to use HS256

     

       221
       221
       +
       		if header.Alg != AlgorithmHS256 {

     

       222
       222
       +
       			return nil, fmt.Errorf("expected HS256 for issuer %s but token uses %s", claims.Issuer, header.Alg)

     

       223
       223
       +
       		}

     

       224
       224
       +
       		return verifyHS256Token(tokenString)

     

       225
       225
       +
       	}

     

       226
       226
       +
       

     

       227
       227
       +
       	// Token must use asymmetric verification

     

       228
       228
       +
       	// Reject HS256 tokens that don't meet the criteria above

     

       229
       229
       +
       	if header.Alg == AlgorithmHS256 {

     

       230
       230
       +
       		if header.Kid != "" {

     

       231
       231
       +
       			return nil, fmt.Errorf("HS256 tokens with kid must use asymmetric verification")

     

       232
       232
       +
       		}

     

       233
       233
       +
       		return nil, fmt.Errorf("HS256 not allowed for issuer %s (not in HS256_ISSUERS whitelist)", claims.Issuer)

     

       234
       234
       +
       	}

     

       235
       235
       +
       

     

       236
       236
       +
       	// For RSA/ECDSA, fetch public key from JWKS and verify

     

       237
       237
       +
       	return verifyAsymmetricToken(ctx, tokenString, claims.Issuer, keyFetcher)

     

       238
       238
       +
       }

     

       239
       239
       +
       

     

       240
       240
       +
       // verifyHS256Token verifies a JWT using HMAC-SHA256 with the shared secret

     

       241
       241
       +
       func verifyHS256Token(tokenString string) (*Claims, error) {

     

       242
       242
       +
       	cfg := getConfig()

     

       243
       243
       +
       	if len(cfg.pdsJWTSecret) == 0 {

     

       244
       244
       +
       		return nil, fmt.Errorf("HS256 verification failed: PDS_JWT_SECRET not configured")

     

       245
       245
       +
       	}

     

       246
       246
       +
       

     

       247
       247
       +
       	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {

     

       248
       248
       +
       		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {

     

       249
       249
       +
       			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])

     

       250
       250
       +
       		}

     

       251
       251
       +
       		return cfg.pdsJWTSecret, nil

     

       252
       252
       +
       	})

     

       253
       253
       +
       	if err != nil {

     

       254
       254
       +
       		return nil, fmt.Errorf("HS256 verification failed: %w", err)

     

       255
       255
       +
       	}

     

       256
       256
       +
       

     

       257
       257
       +
       	if !token.Valid {

     

       258
       258
       +
       		return nil, fmt.Errorf("HS256 verification failed: token signature invalid")

     

       259
       259
       +
       	}

     

       260
       260
       +
       

     

       261
       261
       +
       	verifiedClaims, ok := token.Claims.(*Claims)

     

       262
       262
       +
       	if !ok {

     

       263
       263
       +
       		return nil, fmt.Errorf("HS256 verification failed: invalid claims type")

     

       264
       264
       +
       	}

     

       265
       265
       +
       

     

       266
       266
       +
       	if err := validateClaims(verifiedClaims); err != nil {

     

       267
       267
       +
       		return nil, err

     

       268
       268
       +
       	}

     

       269
       269
       +
       

     

       270
       270
       +
       	return verifiedClaims, nil

     

       271
       271
       +
       }

     

       272
       272
       +
       

     

       273
       273
       +
       // verifyAsymmetricToken verifies a JWT using RSA or ECDSA with a public key from JWKS

     

       274
       274
       +
       func verifyAsymmetricToken(ctx context.Context, tokenString, issuer string, keyFetcher JWKSFetcher) (*Claims, error) {

     

       275
       275
       +
       	publicKey, err := keyFetcher.FetchPublicKey(ctx, issuer, tokenString)

     

       79
       276
        
       	if err != nil {

     

       80
       277
        
       		return nil, fmt.Errorf("failed to fetch public key: %w", err)

     

       81
       278
        
       	}

     

       82
       279
        
       

     

       83
       83
       -
       	// Now parse and verify with the public key

     

       84
       84
       -
       	tokenString = strings.TrimPrefix(tokenString, "Bearer ")

     

       85
       280
        
       	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {

     

       86
       281
        
       		// Validate signing method - support both RSA and ECDSA (atProto uses ES256 primarily)

     

       87
       282
        
       		switch token.Method.(type) {

     
···

       93
       288
        
       		return publicKey, nil

     

       94
       289
        
       	})

     

       95
       290
        
       	if err != nil {

     

       96
       96
       -
       		return nil, fmt.Errorf("failed to verify JWT: %w", err)

     

       291
       291
       +
       		return nil, fmt.Errorf("asymmetric verification failed: %w", err)

     

       97
       292
        
       	}

     

       98
       293
        
       

     

       99
       294
        
       	if !token.Valid {

     

       100
       100
       -
       		return nil, fmt.Errorf("token is invalid")

     

       295
       295
       +
       		return nil, fmt.Errorf("asymmetric verification failed: token signature invalid")

     

       101
       296
        
       	}

     

       102
       297
        
       

     

       103
       298
        
       	verifiedClaims, ok := token.Claims.(*Claims)

     

       104
       299
        
       	if !ok {

     

       105
       105
       -
       		return nil, fmt.Errorf("invalid claims type after verification")

     

       300
       300
       +
       		return nil, fmt.Errorf("asymmetric verification failed: invalid claims type")

     

       106
       301
        
       	}

     

       107
       302
        
       

     

       108
       108
       -
       	// Additional validation

     

       109
       303
        
       	if err := validateClaims(verifiedClaims); err != nil {

     

       110
       304
        
       		return nil, err

     

       111
       305
        
       	}

     
···

       144
       338
        
       	}

     

       145
       339
        
       

     

       146
       340
        
       	// In production, reject HTTP issuers (only for non-dev environments)

     

       147
       147
       -
       	// Check IS_DEV_ENV environment variable

     

       148
       148
       -
       	if isHTTP && os.Getenv("IS_DEV_ENV") != "true" {

     

       341
       341
       +
       	cfg := getConfig()

     

       342
       342
       +
       	if isHTTP && !cfg.isDevEnv {

     

       149
       343
        
       		return fmt.Errorf("HTTP issuer not allowed in production, got: %s", claims.Issuer)

     

       150
       344
        
       	}

     

       151
       345
        
       

     
···

       273
       467
        
       

     

       274
       468
        
       // ExtractKeyID extracts the key ID from a JWT token header

     

       275
       469
        
       func ExtractKeyID(tokenString string) (string, error) {

     

       276
       276
       -
       	tokenString = strings.TrimPrefix(tokenString, "Bearer ")

     

       277
       277
       -
       	parts := strings.Split(tokenString, ".")

     

       278
       278
       -
       	if len(parts) != 3 {

     

       279
       279
       -
       		return "", fmt.Errorf("invalid JWT format")

     

       280
       280
       -
       	}

     

       281
       281
       -
       

     

       282
       282
       -
       	// Decode header

     

       283
       283
       -
       	headerBytes, err := base64.RawURLEncoding.DecodeString(parts[0])

     

       470
       470
       +
       	header, err := ParseJWTHeader(tokenString)

     

       284
       471
        
       	if err != nil {

     

       285
       285
       -
       		return "", fmt.Errorf("failed to decode header: %w", err)

     

       286
       286
       -
       	}

     

       287
       287
       -
       

     

       288
       288
       -
       	var header struct {

     

       289
       289
       -
       		Kid string `json:"kid"`

     

       290
       290
       -
       	}

     

       291
       291
       -
       	if err := json.Unmarshal(headerBytes, &header); err != nil {

     

       292
       292
       -
       		return "", fmt.Errorf("failed to unmarshal header: %w", err)

     

       472
       472
       +
       		return "", err

     

       293
       473
        
       	}

     

       294
       474
        
       

     

       295
       475
        
       	if header.Kid == "" {

+367

internal/atproto/auth/jwt_test.go

···

       1
       1
        
       package auth

     

       2
       2
        
       

     

       3
       3
        
       import (

     

       4
       4
       +
       	"context"

     

       5
       5
       +
       	"os"

     

       4
       6
        
       	"testing"

     

       5
       7
        
       	"time"

     

       6
       8
        
       

     
···

       168
       170
        
       		}

     

       169
       171
        
       	}

     

       170
       172
        
       }

     

       173
       173
       +
       

     

       174
       174
       +
       // === HS256 Verification Tests ===

     

       175
       175
       +
       

     

       176
       176
       +
       // mockJWKSFetcher is a mock implementation of JWKSFetcher for testing

     

       177
       177
       +
       type mockJWKSFetcher struct {

     

       178
       178
       +
       	publicKey interface{}

     

       179
       179
       +
       	err       error

     

       180
       180
       +
       }

     

       181
       181
       +
       

     

       182
       182
       +
       func (m *mockJWKSFetcher) FetchPublicKey(ctx context.Context, issuer, token string) (interface{}, error) {

     

       183
       183
       +
       	return m.publicKey, m.err

     

       184
       184
       +
       }

     

       185
       185
       +
       

     

       186
       186
       +
       func createHS256Token(t *testing.T, subject, issuer, secret string, expiry time.Duration) string {

     

       187
       187
       +
       	t.Helper()

     

       188
       188
       +
       	claims := &Claims{

     

       189
       189
       +
       		RegisteredClaims: jwt.RegisteredClaims{

     

       190
       190
       +
       			Subject:   subject,

     

       191
       191
       +
       			Issuer:    issuer,

     

       192
       192
       +
       			ExpiresAt: jwt.NewNumericDate(time.Now().Add(expiry)),

     

       193
       193
       +
       			IssuedAt:  jwt.NewNumericDate(time.Now()),

     

       194
       194
       +
       		},

     

       195
       195
       +
       		Scope: "atproto transition:generic",

     

       196
       196
       +
       	}

     

       197
       197
       +
       	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)

     

       198
       198
       +
       	tokenString, err := token.SignedString([]byte(secret))

     

       199
       199
       +
       	if err != nil {

     

       200
       200
       +
       		t.Fatalf("Failed to create test token: %v", err)

     

       201
       201
       +
       	}

     

       202
       202
       +
       	return tokenString

     

       203
       203
       +
       }

     

       204
       204
       +
       

     

       205
       205
       +
       func TestVerifyJWT_HS256_Valid(t *testing.T) {

     

       206
       206
       +
       	// Setup: Configure environment for HS256 verification

     

       207
       207
       +
       	secret := "test-jwt-secret-key-12345"

     

       208
       208
       +
       	issuer := "https://pds.coves.social"

     

       209
       209
       +
       

     

       210
       210
       +
       	ResetJWTConfigForTesting()

     

       211
       211
       +
       	os.Setenv("PDS_JWT_SECRET", secret)

     

       212
       212
       +
       	os.Setenv("HS256_ISSUERS", issuer)

     

       213
       213
       +
       	defer func() {

     

       214
       214
       +
       		os.Unsetenv("PDS_JWT_SECRET")

     

       215
       215
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       216
       216
       +
       		ResetJWTConfigForTesting()

     

       217
       217
       +
       	}()

     

       218
       218
       +
       

     

       219
       219
       +
       	tokenString := createHS256Token(t, "did:plc:test123", issuer, secret, 1*time.Hour)

     

       220
       220
       +
       

     

       221
       221
       +
       	// Verify token

     

       222
       222
       +
       	claims, err := VerifyJWT(context.Background(), tokenString, &mockJWKSFetcher{})

     

       223
       223
       +
       	if err != nil {

     

       224
       224
       +
       		t.Fatalf("VerifyJWT failed for valid HS256 token: %v", err)

     

       225
       225
       +
       	}

     

       226
       226
       +
       

     

       227
       227
       +
       	if claims.Subject != "did:plc:test123" {

     

       228
       228
       +
       		t.Errorf("Expected subject 'did:plc:test123', got '%s'", claims.Subject)

     

       229
       229
       +
       	}

     

       230
       230
       +
       	if claims.Issuer != issuer {

     

       231
       231
       +
       		t.Errorf("Expected issuer '%s', got '%s'", issuer, claims.Issuer)

     

       232
       232
       +
       	}

     

       233
       233
       +
       }

     

       234
       234
       +
       

     

       235
       235
       +
       func TestVerifyJWT_HS256_WrongSecret(t *testing.T) {

     

       236
       236
       +
       	// Setup: Configure environment with one secret, sign with another

     

       237
       237
       +
       	issuer := "https://pds.coves.social"

     

       238
       238
       +
       

     

       239
       239
       +
       	ResetJWTConfigForTesting()

     

       240
       240
       +
       	os.Setenv("PDS_JWT_SECRET", "correct-secret")

     

       241
       241
       +
       	os.Setenv("HS256_ISSUERS", issuer)

     

       242
       242
       +
       	defer func() {

     

       243
       243
       +
       		os.Unsetenv("PDS_JWT_SECRET")

     

       244
       244
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       245
       245
       +
       		ResetJWTConfigForTesting()

     

       246
       246
       +
       	}()

     

       247
       247
       +
       

     

       248
       248
       +
       	// Create token with wrong secret

     

       249
       249
       +
       	tokenString := createHS256Token(t, "did:plc:test123", issuer, "wrong-secret", 1*time.Hour)

     

       250
       250
       +
       

     

       251
       251
       +
       	// Verify should fail

     

       252
       252
       +
       	_, err := VerifyJWT(context.Background(), tokenString, &mockJWKSFetcher{})

     

       253
       253
       +
       	if err == nil {

     

       254
       254
       +
       		t.Error("Expected error for HS256 token with wrong secret, got nil")

     

       255
       255
       +
       	}

     

       256
       256
       +
       }

     

       257
       257
       +
       

     

       258
       258
       +
       func TestVerifyJWT_HS256_SecretNotConfigured(t *testing.T) {

     

       259
       259
       +
       	// Setup: Whitelist issuer but don't configure secret

     

       260
       260
       +
       	issuer := "https://pds.coves.social"

     

       261
       261
       +
       

     

       262
       262
       +
       	ResetJWTConfigForTesting()

     

       263
       263
       +
       	os.Unsetenv("PDS_JWT_SECRET") // Ensure secret is not set

     

       264
       264
       +
       	os.Setenv("HS256_ISSUERS", issuer)

     

       265
       265
       +
       	defer func() {

     

       266
       266
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       267
       267
       +
       		ResetJWTConfigForTesting()

     

       268
       268
       +
       	}()

     

       269
       269
       +
       

     

       270
       270
       +
       	tokenString := createHS256Token(t, "did:plc:test123", issuer, "any-secret", 1*time.Hour)

     

       271
       271
       +
       

     

       272
       272
       +
       	// Verify should fail with descriptive error

     

       273
       273
       +
       	_, err := VerifyJWT(context.Background(), tokenString, &mockJWKSFetcher{})

     

       274
       274
       +
       	if err == nil {

     

       275
       275
       +
       		t.Error("Expected error when PDS_JWT_SECRET not configured, got nil")

     

       276
       276
       +
       	}

     

       277
       277
       +
       	if err != nil && !contains(err.Error(), "PDS_JWT_SECRET not configured") {

     

       278
       278
       +
       		t.Errorf("Expected error about PDS_JWT_SECRET not configured, got: %v", err)

     

       279
       279
       +
       	}

     

       280
       280
       +
       }

     

       281
       281
       +
       

     

       282
       282
       +
       // === Algorithm Confusion Attack Prevention Tests ===

     

       283
       283
       +
       

     

       284
       284
       +
       func TestVerifyJWT_AlgorithmConfusionAttack_HS256WithNonWhitelistedIssuer(t *testing.T) {

     

       285
       285
       +
       	// SECURITY TEST: This tests the algorithm confusion attack prevention

     

       286
       286
       +
       	// An attacker tries to use HS256 with an issuer that should use RS256/ES256

     

       287
       287
       +
       

     

       288
       288
       +
       	ResetJWTConfigForTesting()

     

       289
       289
       +
       	os.Setenv("PDS_JWT_SECRET", "some-secret")

     

       290
       290
       +
       	os.Setenv("HS256_ISSUERS", "https://trusted.example.com") // Different from token issuer

     

       291
       291
       +
       	defer func() {

     

       292
       292
       +
       		os.Unsetenv("PDS_JWT_SECRET")

     

       293
       293
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       294
       294
       +
       		ResetJWTConfigForTesting()

     

       295
       295
       +
       	}()

     

       296
       296
       +
       

     

       297
       297
       +
       	// Create HS256 token with non-whitelisted issuer (simulating attack)

     

       298
       298
       +
       	tokenString := createHS256Token(t, "did:plc:attacker", "https://victim-pds.example.com", "some-secret", 1*time.Hour)

     

       299
       299
       +
       

     

       300
       300
       +
       	// Verify should fail because issuer is not in HS256 whitelist

     

       301
       301
       +
       	_, err := VerifyJWT(context.Background(), tokenString, &mockJWKSFetcher{})

     

       302
       302
       +
       	if err == nil {

     

       303
       303
       +
       		t.Error("SECURITY VULNERABILITY: HS256 token accepted for non-whitelisted issuer")

     

       304
       304
       +
       	}

     

       305
       305
       +
       	if err != nil && !contains(err.Error(), "not in HS256_ISSUERS whitelist") {

     

       306
       306
       +
       		t.Errorf("Expected error about HS256 not allowed for issuer, got: %v", err)

     

       307
       307
       +
       	}

     

       308
       308
       +
       }

     

       309
       309
       +
       

     

       310
       310
       +
       func TestVerifyJWT_AlgorithmConfusionAttack_EmptyWhitelist(t *testing.T) {

     

       311
       311
       +
       	// SECURITY TEST: When no issuers are whitelisted for HS256, all HS256 tokens should be rejected

     

       312
       312
       +
       

     

       313
       313
       +
       	ResetJWTConfigForTesting()

     

       314
       314
       +
       	os.Setenv("PDS_JWT_SECRET", "some-secret")

     

       315
       315
       +
       	os.Unsetenv("HS256_ISSUERS") // Empty whitelist

     

       316
       316
       +
       	defer func() {

     

       317
       317
       +
       		os.Unsetenv("PDS_JWT_SECRET")

     

       318
       318
       +
       		ResetJWTConfigForTesting()

     

       319
       319
       +
       	}()

     

       320
       320
       +
       

     

       321
       321
       +
       	tokenString := createHS256Token(t, "did:plc:test123", "https://any-pds.example.com", "some-secret", 1*time.Hour)

     

       322
       322
       +
       

     

       323
       323
       +
       	// Verify should fail because no issuers are whitelisted for HS256

     

       324
       324
       +
       	_, err := VerifyJWT(context.Background(), tokenString, &mockJWKSFetcher{})

     

       325
       325
       +
       	if err == nil {

     

       326
       326
       +
       		t.Error("SECURITY VULNERABILITY: HS256 token accepted with empty issuer whitelist")

     

       327
       327
       +
       	}

     

       328
       328
       +
       }

     

       329
       329
       +
       

     

       330
       330
       +
       func TestVerifyJWT_IssuerRequiresHS256ButTokenUsesRS256(t *testing.T) {

     

       331
       331
       +
       	// Test that issuer whitelisted for HS256 rejects tokens claiming to use RS256

     

       332
       332
       +
       	issuer := "https://pds.coves.social"

     

       333
       333
       +
       

     

       334
       334
       +
       	ResetJWTConfigForTesting()

     

       335
       335
       +
       	os.Setenv("PDS_JWT_SECRET", "test-secret")

     

       336
       336
       +
       	os.Setenv("HS256_ISSUERS", issuer)

     

       337
       337
       +
       	defer func() {

     

       338
       338
       +
       		os.Unsetenv("PDS_JWT_SECRET")

     

       339
       339
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       340
       340
       +
       		ResetJWTConfigForTesting()

     

       341
       341
       +
       	}()

     

       342
       342
       +
       

     

       343
       343
       +
       	// Create RS256-signed token (can't actually sign without RSA key, but we can test the header check)

     

       344
       344
       +
       	claims := &Claims{

     

       345
       345
       +
       		RegisteredClaims: jwt.RegisteredClaims{

     

       346
       346
       +
       			Subject:   "did:plc:test123",

     

       347
       347
       +
       			Issuer:    issuer,

     

       348
       348
       +
       			ExpiresAt: jwt.NewNumericDate(time.Now().Add(1 * time.Hour)),

     

       349
       349
       +
       		},

     

       350
       350
       +
       	}

     

       351
       351
       +
       	token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)

     

       352
       352
       +
       	// This will create an invalid signature but valid header structure

     

       353
       353
       +
       	// The test should fail at algorithm check, not signature verification

     

       354
       354
       +
       	tokenString, _ := token.SignedString([]byte("dummy-key"))

     

       355
       355
       +
       

     

       356
       356
       +
       	if tokenString != "" {

     

       357
       357
       +
       		_, err := VerifyJWT(context.Background(), tokenString, &mockJWKSFetcher{})

     

       358
       358
       +
       		if err == nil {

     

       359
       359
       +
       			t.Error("Expected error when HS256 issuer receives non-HS256 token")

     

       360
       360
       +
       		}

     

       361
       361
       +
       	}

     

       362
       362
       +
       }

     

       363
       363
       +
       

     

       364
       364
       +
       // === ParseJWTHeader Tests ===

     

       365
       365
       +
       

     

       366
       366
       +
       func TestParseJWTHeader_Valid(t *testing.T) {

     

       367
       367
       +
       	tokenString := createHS256Token(t, "did:plc:test123", "https://test.example.com", "secret", 1*time.Hour)

     

       368
       368
       +
       

     

       369
       369
       +
       	header, err := ParseJWTHeader(tokenString)

     

       370
       370
       +
       	if err != nil {

     

       371
       371
       +
       		t.Fatalf("ParseJWTHeader failed: %v", err)

     

       372
       372
       +
       	}

     

       373
       373
       +
       

     

       374
       374
       +
       	if header.Alg != AlgorithmHS256 {

     

       375
       375
       +
       		t.Errorf("Expected alg '%s', got '%s'", AlgorithmHS256, header.Alg)

     

       376
       376
       +
       	}

     

       377
       377
       +
       }

     

       378
       378
       +
       

     

       379
       379
       +
       func TestParseJWTHeader_WithBearerPrefix(t *testing.T) {

     

       380
       380
       +
       	tokenString := createHS256Token(t, "did:plc:test123", "https://test.example.com", "secret", 1*time.Hour)

     

       381
       381
       +
       

     

       382
       382
       +
       	header, err := ParseJWTHeader("Bearer " + tokenString)

     

       383
       383
       +
       	if err != nil {

     

       384
       384
       +
       		t.Fatalf("ParseJWTHeader failed with Bearer prefix: %v", err)

     

       385
       385
       +
       	}

     

       386
       386
       +
       

     

       387
       387
       +
       	if header.Alg != AlgorithmHS256 {

     

       388
       388
       +
       		t.Errorf("Expected alg '%s', got '%s'", AlgorithmHS256, header.Alg)

     

       389
       389
       +
       	}

     

       390
       390
       +
       }

     

       391
       391
       +
       

     

       392
       392
       +
       func TestParseJWTHeader_InvalidFormat(t *testing.T) {

     

       393
       393
       +
       	testCases := []struct {

     

       394
       394
       +
       		name  string

     

       395
       395
       +
       		input string

     

       396
       396
       +
       	}{

     

       397
       397
       +
       		{"empty string", ""},

     

       398
       398
       +
       		{"single part", "abc"},

     

       399
       399
       +
       		{"two parts", "abc.def"},

     

       400
       400
       +
       		{"too many parts", "a.b.c.d"},

     

       401
       401
       +
       	}

     

       402
       402
       +
       

     

       403
       403
       +
       	for _, tc := range testCases {

     

       404
       404
       +
       		t.Run(tc.name, func(t *testing.T) {

     

       405
       405
       +
       			_, err := ParseJWTHeader(tc.input)

     

       406
       406
       +
       			if err == nil {

     

       407
       407
       +
       				t.Errorf("Expected error for invalid JWT format '%s', got nil", tc.input)

     

       408
       408
       +
       			}

     

       409
       409
       +
       		})

     

       410
       410
       +
       	}

     

       411
       411
       +
       }

     

       412
       412
       +
       

     

       413
       413
       +
       // === shouldUseHS256 and isHS256IssuerWhitelisted Tests ===

     

       414
       414
       +
       

     

       415
       415
       +
       func TestIsHS256IssuerWhitelisted_Whitelisted(t *testing.T) {

     

       416
       416
       +
       	ResetJWTConfigForTesting()

     

       417
       417
       +
       	os.Setenv("HS256_ISSUERS", "https://pds1.example.com,https://pds2.example.com")

     

       418
       418
       +
       	defer func() {

     

       419
       419
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       420
       420
       +
       		ResetJWTConfigForTesting()

     

       421
       421
       +
       	}()

     

       422
       422
       +
       

     

       423
       423
       +
       	if !isHS256IssuerWhitelisted("https://pds1.example.com") {

     

       424
       424
       +
       		t.Error("Expected pds1 to be whitelisted")

     

       425
       425
       +
       	}

     

       426
       426
       +
       	if !isHS256IssuerWhitelisted("https://pds2.example.com") {

     

       427
       427
       +
       		t.Error("Expected pds2 to be whitelisted")

     

       428
       428
       +
       	}

     

       429
       429
       +
       }

     

       430
       430
       +
       

     

       431
       431
       +
       func TestIsHS256IssuerWhitelisted_NotWhitelisted(t *testing.T) {

     

       432
       432
       +
       	ResetJWTConfigForTesting()

     

       433
       433
       +
       	os.Setenv("HS256_ISSUERS", "https://pds1.example.com")

     

       434
       434
       +
       	defer func() {

     

       435
       435
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       436
       436
       +
       		ResetJWTConfigForTesting()

     

       437
       437
       +
       	}()

     

       438
       438
       +
       

     

       439
       439
       +
       	if isHS256IssuerWhitelisted("https://attacker.example.com") {

     

       440
       440
       +
       		t.Error("Expected non-whitelisted issuer to return false")

     

       441
       441
       +
       	}

     

       442
       442
       +
       }

     

       443
       443
       +
       

     

       444
       444
       +
       func TestIsHS256IssuerWhitelisted_EmptyWhitelist(t *testing.T) {

     

       445
       445
       +
       	ResetJWTConfigForTesting()

     

       446
       446
       +
       	os.Unsetenv("HS256_ISSUERS")

     

       447
       447
       +
       	defer ResetJWTConfigForTesting()

     

       448
       448
       +
       

     

       449
       449
       +
       	if isHS256IssuerWhitelisted("https://any.example.com") {

     

       450
       450
       +
       		t.Error("Expected false when whitelist is empty (safe default)")

     

       451
       451
       +
       	}

     

       452
       452
       +
       }

     

       453
       453
       +
       

     

       454
       454
       +
       func TestIsHS256IssuerWhitelisted_WhitespaceHandling(t *testing.T) {

     

       455
       455
       +
       	ResetJWTConfigForTesting()

     

       456
       456
       +
       	os.Setenv("HS256_ISSUERS", "  https://pds1.example.com  ,  https://pds2.example.com  ")

     

       457
       457
       +
       	defer func() {

     

       458
       458
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       459
       459
       +
       		ResetJWTConfigForTesting()

     

       460
       460
       +
       	}()

     

       461
       461
       +
       

     

       462
       462
       +
       	if !isHS256IssuerWhitelisted("https://pds1.example.com") {

     

       463
       463
       +
       		t.Error("Expected whitespace-trimmed issuer to be whitelisted")

     

       464
       464
       +
       	}

     

       465
       465
       +
       }

     

       466
       466
       +
       

     

       467
       467
       +
       // === shouldUseHS256 Tests (kid-based logic) ===

     

       468
       468
       +
       

     

       469
       469
       +
       func TestShouldUseHS256_WithKid_AlwaysFalse(t *testing.T) {

     

       470
       470
       +
       	// Tokens with kid should NEVER use HS256, regardless of issuer whitelist

     

       471
       471
       +
       	ResetJWTConfigForTesting()

     

       472
       472
       +
       	os.Setenv("HS256_ISSUERS", "https://whitelisted.example.com")

     

       473
       473
       +
       	defer func() {

     

       474
       474
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       475
       475
       +
       		ResetJWTConfigForTesting()

     

       476
       476
       +
       	}()

     

       477
       477
       +
       

     

       478
       478
       +
       	header := &JWTHeader{

     

       479
       479
       +
       		Alg: AlgorithmHS256,

     

       480
       480
       +
       		Kid: "some-key-id", // Has kid

     

       481
       481
       +
       	}

     

       482
       482
       +
       

     

       483
       483
       +
       	// Even whitelisted issuer should not use HS256 if token has kid

     

       484
       484
       +
       	if shouldUseHS256(header, "https://whitelisted.example.com") {

     

       485
       485
       +
       		t.Error("Tokens with kid should never use HS256 (supports federation)")

     

       486
       486
       +
       	}

     

       487
       487
       +
       }

     

       488
       488
       +
       

     

       489
       489
       +
       func TestShouldUseHS256_WithoutKid_WhitelistedIssuer(t *testing.T) {

     

       490
       490
       +
       	ResetJWTConfigForTesting()

     

       491
       491
       +
       	os.Setenv("HS256_ISSUERS", "https://my-pds.example.com")

     

       492
       492
       +
       	defer func() {

     

       493
       493
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       494
       494
       +
       		ResetJWTConfigForTesting()

     

       495
       495
       +
       	}()

     

       496
       496
       +
       

     

       497
       497
       +
       	header := &JWTHeader{

     

       498
       498
       +
       		Alg: AlgorithmHS256,

     

       499
       499
       +
       		Kid: "", // No kid

     

       500
       500
       +
       	}

     

       501
       501
       +
       

     

       502
       502
       +
       	if !shouldUseHS256(header, "https://my-pds.example.com") {

     

       503
       503
       +
       		t.Error("Token without kid from whitelisted issuer should use HS256")

     

       504
       504
       +
       	}

     

       505
       505
       +
       }

     

       506
       506
       +
       

     

       507
       507
       +
       func TestShouldUseHS256_WithoutKid_NotWhitelisted(t *testing.T) {

     

       508
       508
       +
       	ResetJWTConfigForTesting()

     

       509
       509
       +
       	os.Setenv("HS256_ISSUERS", "https://my-pds.example.com")

     

       510
       510
       +
       	defer func() {

     

       511
       511
       +
       		os.Unsetenv("HS256_ISSUERS")

     

       512
       512
       +
       		ResetJWTConfigForTesting()

     

       513
       513
       +
       	}()

     

       514
       514
       +
       

     

       515
       515
       +
       	header := &JWTHeader{

     

       516
       516
       +
       		Alg: AlgorithmHS256,

     

       517
       517
       +
       		Kid: "", // No kid

     

       518
       518
       +
       	}

     

       519
       519
       +
       

     

       520
       520
       +
       	if shouldUseHS256(header, "https://external-pds.example.com") {

     

       521
       521
       +
       		t.Error("Token without kid from non-whitelisted issuer should NOT use HS256")

     

       522
       522
       +
       	}

     

       523
       523
       +
       }

     

       524
       524
       +
       

     

       525
       525
       +
       // Helper function

     

       526
       526
       +
       func contains(s, substr string) bool {

     

       527
       527
       +
       	return len(s) >= len(substr) && (s == substr || len(s) > 0 && containsHelper(s, substr))

     

       528
       528
       +
       }

     

       529
       529
       +
       

     

       530
       530
       +
       func containsHelper(s, substr string) bool {

     

       531
       531
       +
       	for i := 0; i <= len(s)-len(substr); i++ {

     

       532
       532
       +
       		if s[i:i+len(substr)] == substr {

     

       533
       533
       +
       			return true

     

       534
       534
       +
       		}

     

       535
       535
       +
       	}

     

       536
       536
       +
       	return false

     

       537
       537
       +
       }