public static BigInteger bytes2Integer(byte[] bs) {
    return BigIntegerEncoding.fromUnsignedBigEndianBytes(bs);
  }
Converts an unsigned, big-endian encoded byte array to a non-negative integer
(https://tools.ietf.org/html/rfc8017#section-4.1).

@param bs the byte array to be converted to integer.
@return the corresponding integer.
java_src/src/main/java/com/google/crypto/tink/subtle/SubtleUtil.java