public byte[] hash(byte[] data) throws SdkClientException {
        try {
            MessageDigest md =  getMessageDigestInstance();
            md.update(data);
            return md.digest();
        } catch (Exception e) {
            throw new SdkClientException(
                    "Unable to compute hash while signing request: "
                            + e.getMessage(), e);
        }
    }
Hashes the binary data using the SHA-256 algorithm.

@param data
           The binary data to hash.

@return The hashed bytes from the specified data.

@throws SdkClientException
            If the hash cannot be computed.
aws-java-sdk-core/src/main/java/com/amazonaws/auth/AbstractAWSSigner.java