public static RsaSsaPkcs1PublicKey createRsaSsaPkcs1PubKey(
      byte[] modulus, byte[] exponent, HashType hashType) throws Exception {
    final int version = 0;
    RsaSsaPkcs1Params params = RsaSsaPkcs1Params.newBuilder().setHashType(hashType).build();

    return RsaSsaPkcs1PublicKey.newBuilder()
        .setVersion(version)
        .setParams(params)
        .setN(ByteString.copyFrom(modulus))
        .setE(ByteString.copyFrom(exponent))
        .build();
  }
@return a {@code RsaSsaPkcs1PublicKey} constructed from {@code modulus}, {@code exponent} and
    {@code hashType}.
java_src/src/main/java/com/google/crypto/tink/testing/TestUtil.java