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Verify holder cryptographic binding #47

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bd1b3a3
Fix url vct integrity check
patatoid Sep 24, 2025
0f3ba14
Holder cryptographic binding optional verification
patatoid Sep 24, 2025
40148b6
Remove unused holder public key in sd jwt verify result
patatoid Sep 24, 2025
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74 changes: 57 additions & 17 deletions src/credential-verifiers/SDJWTVCVerifier.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -200,14 +200,18 @@ export function SDJWTVCVerifier(args: { context: Context, pkResolverEngine: Publ

const fetchVctFromRegistry = async function (urnOrUrl: string, integrity?: string) {
if (urnOrUrl.startsWith('https')) {
const SdJwtVc = new SDJwtVcInstance({
hasher: hasherAndAlgorithm.hasher,
})

const url = urnOrUrl

const vctm = await args.httpClient.get(url).then(({ data }) => {
return data as { vct: string }
})

// @ts-ignore
const isIntegrityValid = await SdJwtVc.validateIntegrity(vctm, uri, integrity)
const isIntegrityValid = await SdJwtVc.validateIntegrity(vctm, url, integrity)

return vctm
}
Expand Down Expand Up @@ -269,11 +273,11 @@ export function SDJWTVCVerifier(args: { context: Context, pkResolverEngine: Publ
success: true,
value: {},
}
} else {
return {
success: false,
error: CredentialVerificationError.VctSchemaError,
}
}

return {
success: false,
error: CredentialVerificationError.VctSchemaError,
}
}

Expand All @@ -283,6 +287,42 @@ export function SDJWTVCVerifier(args: { context: Context, pkResolverEngine: Publ
}
}

const verifyCnf = async (rawCredential: string, opts: {}) => {
const SdJwtVc = new SDJwtVcInstance({
verifier: () => true,
hasher: hasherAndAlgorithm.hasher,
hashAlg: hasherAndAlgorithm.alg as 'sha-256',
loadTypeMetadataFormat: true,
vctFetcher: fetchVctFromRegistry,
});

const publicKeyResult = await getHolderPublicKey(rawCredential);
if (!publicKeyResult.success) {
logError(CredentialVerificationError.CannotExtractHolderPublicKey, "CannotExtractHolderPublicKey");
return {
success: false,
error: publicKeyResult.error,
}
}

try {
const jwt = rawCredential.split("~")[0];
await jwtVerify(jwt, publicKeyResult.value, { clockTolerance: args.context.clockTolerance });
}
catch (err: any) {
logError(CredentialVerificationError.KbJwtVerificationFailedSignatureValidation, "Error on verifyCnf(): Invalid SD-JWT signature");
return {
success: false,
error: CredentialVerificationError.KbJwtVerificationFailedSignatureValidation,
};
}

return {
success: true,
value: {},
}
}

const verifyKbJwt = async (rawPresentation: string, opts: {
expectedNonce?: string;
expectedAudience?: string;
Expand Down Expand Up @@ -385,6 +425,17 @@ export function SDJWTVCVerifier(args: { context: Context, pkResolverEngine: Publ
}
}

// cnf (cryptographic holder binding) validation
if (opts.verifyCnf) {
const verifyCnfResult = await verifyCnf(rawCredential, opts);
if (!verifyCnfResult.success) {
return {
success: false,
error: errors.length > 0 ? errors[0].error : CredentialVerificationError.UnknownProblem,
}
}
}

// KB-JWT validation
if (!rawCredential.endsWith('~')) { // contains kbjwt
const verifyKbJwtResult = await verifyKbJwt(rawCredential, opts);
Expand All @@ -396,20 +447,9 @@ export function SDJWTVCVerifier(args: { context: Context, pkResolverEngine: Publ
}
}

const publicKeyResult = await getHolderPublicKey(rawCredential);
if (publicKeyResult.success === false) {
logError(CredentialVerificationError.CannotExtractHolderPublicKey, "Could not extract holder public key");
return {
success: false,
error: errors.length > 0 ? errors[0].error : CredentialVerificationError.UnknownProblem,
}
}

return {
success: true,
value: {
valid: true,
holderPublicKey: await exportJWK(publicKeyResult.value),
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@patatoid patatoid Sep 24, 2025

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@kkmanos I am not sure if that value is not used within the components. Can you confirm?

},
}
},
Expand Down
6 changes: 3 additions & 3 deletions src/interfaces.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ export interface ParsingEngineI {

export interface VerifyingEngineI {
register(credentialVerifier: CredentialVerifier): void;
verify({ rawCredential, opts }: { rawCredential: unknown, opts: { expectedNonce?: string, expectedAudience?: string, holderNonce?: string, responseUri?: string, verifySchema?: boolean } }): Promise<Result<{ holderPublicKey: JWK; }, CredentialVerificationError>>;
verify({ rawCredential, opts }: { rawCredential: unknown, opts: { expectedNonce?: string, expectedAudience?: string, holderNonce?: string, responseUri?: string, verifySchema?: boolean, verifyCnf?: boolean } }): Promise<Result<{ holderPublicKey?: JWK; }, CredentialVerificationError>>;
}

export interface PublicKeyResolverEngineI {
Expand All @@ -49,8 +49,8 @@ export interface CredentialParser {
}

export interface CredentialVerifier {
verify(args: { rawCredential: unknown, opts: { expectedNonce?: string, expectedAudience?: string, holderNonce?: string, responseUri?: string, verifySchema?: boolean } }): Promise<Result<{
holderPublicKey: JWK,
verify(args: { rawCredential: unknown, opts: { expectedNonce?: string, expectedAudience?: string, holderNonce?: string, responseUri?: string, verifySchema?: boolean, verifyCnf?: boolean } }): Promise<Result<{
holderPublicKey?: JWK,
}, CredentialVerificationError>>;
}

Expand Down