code: function assertSignVerify(msg, jwkey, hash, algorithm, mode){
    if (algorithm.name !== 'RSA-PSS' && algorithm.name !== 'RSASSA-PKCS1-v1_5') throw new Error('InvalidAlgorithm');
    if (Object.keys(params.hashes).indexOf(hash) < 0) throw new Error('UnsupportedHash');
    if (!(msg instanceof Uint8Array)) throw new Error('InvalidMessageFormat');
    if (jwkey.kty !== 'RSA') throw new Error('InvalidJwkRsaKey');
    if (algorithm.name === 'RSA-PSS'){
      checkPssLength(mode, {k: jseu.encoder.decodeBase64Url(jwkey.n).length, hash, saltLength: algorithm.saltLength});
    }
    return true;
  }
docs: RSA Signing parameter check.
  @param {Uint8Array} msg - Byte array of message to be signed.
  @param {JsonWebKey} jwkey - Private/Public key for signing/verifying in JWK format.
  @param {String} hash - Name of hash algorithm like 'SHA-256'.
  @param {RSASignAlgorithm} algorithm - Object to specify algorithm parameters.
  @param {String} mode - 'sign' or 'verify' for PSS parameter check.
  @return {boolean} - Always true unless thrown.
  @throws {Error} - Throws if InvalidAlgorithm, UnsupportedHash, InvalidMessageFormat or InvalidJwkRsaKey