I am trying to create a signature using the HMAC-SHA256 algorithm and this is my code. I am using US ASCII encoding.
final Charset asciiCs = Charset.forName("US-ASCII");
final Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
final SecretKeySpec secret_key = new javax.crypto.spec.SecretKeySpec(asciiCs.encode("key").array(), "HmacSHA256");
final byte[] mac_data = sha256_HMAC.doFinal(asciiCs.encode("The quick brown fox jumps over the lazy dog").array());
String result = "";
for (final byte element : mac_data)
{
result += Integer.toString((element & 0xff) + 0x100, 16).substring(1);
}
System.out.println("Result:[" + result + "]");
The result that I am getting from the above code is:
f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8
This is same as to that of shown in the wiki
HMAC_SHA256("key", "The quick brown fox jumps over the lazy dog") = 0x f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8
except for the 0x
.
I am looking for ideas/comments if I am doing everything right or may be I can improve my code.
Here is my solution:
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);
return Hex.encodeHexString(sha256_HMAC.doFinal(data.getBytes("UTF-8")));
}
public static void main(String [] args) throws Exception {
System.out.println(encode("key", "The quick brown fox jumps over the lazy dog"));
}
Or you can return the hash encoded in Base64:
Base64.encodeBase64String(sha256_HMAC.doFinal(data.getBytes("UTF-8")));
The output in hex is as expected:
f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8