Function computeJwkThumbprint

  • computeJwkThumbprint(jwk): Promise<string>

  • Computes the thumbprint of a JSON Web Key (JWK) using the method specified in RFC 7638. This function accepts RSA, EC, OKP, and oct keys and returns the thumbprint as a base64url encoded SHA-256 hash of the JWK's required members, serialized and sorted lexicographically.

    Purpose:

    • Uniquely Identifying Keys: The thumbprint allows the unique identification of a specific JWK within a set of JWKs. It provides a deterministic way to generate a value that can be used as a key identifier (kid) or to match a specific key.

    • Simplifying Key Management: In systems where multiple keys are used, managing and identifying individual keys can become complex. The thumbprint method simplifies this by creating a standardized, unique identifier for each key.

    • Enabling Interoperability: By standardizing the method to compute a thumbprint, different systems can compute the same thumbprint value for a given JWK. This enables interoperability among systems that use JWKs.

    • Secure Comparison: The thumbprint provides a way to securely compare JWKs to determine if they are equivalent.

    Parameters

    • jwk: {
          jwk: Jwk;
      }

      The JSON Web Key for which the thumbprint will be computed. This must be an RSA, EC, OKP, or oct key.

    Returns Promise<string>

    The thumbprint as a base64url encoded string.

    Example

    const jwk: PublicKeyJwk = {
      'kty': 'EC',
      'crv': 'secp256k1',
      'x': '61iPYuGefxotzBdQZtDvv6cWHZmXrTTscY-u7Y2pFZc',
      'y': '88nPCVLfrAY9i-wg5ORcwVbHWC_tbeAd1JE2e0co0lU'
    };

    const thumbprint = jwkThumbprint(jwk);
    console.log(`JWK thumbprint: ${thumbprint}`);

    See

    RFC7638 for the specification of JWK thumbprint computation.

    Throws

    Throws an Error if the provided key type is unsupported.

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