DECRYPTION : Please help

[Thomas Mcfarrow]

Hi,

I am encrypting data like the following:

	public static String encode(String key, String data) throws Exception {
		Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
		SecretKeySpec secret_key = new SecretKeySpec(key.getBytes("UTF-8"),
				"HmacSHA256");
		sha256_HMAC.init(secret_key);
		
		byte[] payload =sha256_HMAC.doFinal(data.getBytes("UTF-8"));
		return new String(Hex.encodeHex(payload));
	}

How do I decrypt it?

public static String decode(String key, String data) throws Exception {
		Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
		SecretKeySpec secret_key = new SecretKeySpec(key.getBytes("UTF-8"),
				"HmacSHA256");
		sha256_HMAC.init(secret_key);
		
		// Remove the 64 bit encoding
		byte[] payload = Hex.decodeHex(data.toCharArray());

??? -- not sure what to do next
-----------------------------------------------------------------

public static void main(String[] args) throws Exception {
		String data = encode("key",
				"The quick brown fox jumps over the lazy dog"));
		System.out.println(data);
		String decodeStr = decode("key", data);
		System.out.println(decodeStr);
	}

Thanks

[Ulf Dittmer]

SHA is not a cipher, it's a digest (or hash) - that means once it's applied to text it can't be reversed, so there's no way to get back the original text. If you need to decrypt, use a cipher like AES: https://coderanch.com/how-to/java/SecurityFaq#encryption