private static SecretBigInteger decodeSecretBigInteger(ByteString data, SecretKeyAccess access) {
    return SecretBigInteger.fromBigInteger(
        BigIntegerEncoding.fromUnsignedBigEndianBytes(data.toByteArray()), access);
  }
Encodes a BigInteger using a big-endian encoding.
java_src/src/main/java/com/google/crypto/tink/signature/internal/RsaSsaPssProtoSerialization.java