How to generate an HMAC in Java equivalent to a Python example?

Question

I'm looking at implementing an app getting Twitter authorization via Oauth in Java. The first step is getting a request token. Here is a Python example for app engine. To test my code, I am running Python and checking output with Java. Here is an example of Python generating a Hash-Based Message Authentication Code (HMAC): ``` #!/usr/bin/python from hashlib import sha1 from hmac import new as hmac key = "qnscAdgRlkIhAUPY44oiexBKtQbGY0orf7OV1I50" message = "foo" print "%s" % hmac(key, message, sha1).digest().encode('base64')[:-1] ``` Output: ``` $ ./foo.py +3h2gpjf4xcynjCGU5lbdMBwGOc= ``` How does one replicate this example in Java? I've seen an example of HMAC in Java: ``` try { // Generate a key for the HMAC-MD5 keyed-hashing algorithm; see RFC 2104 // In practice, you would save this key. KeyGenerator keyGen = KeyGenerator.getInstance("HmacMD5"); SecretKey key = keyGen.generateKey(); // Create a MAC object using HMAC-MD5 and initialize with key Mac mac = Mac.getInstance(key.getAlgor…

Accepted Answer

HmacSHA1 seems to be the algorithm name you need:

```
SecretKeySpec keySpec = new SecretKeySpec(
        "qnscAdgRlkIhAUPY44oiexBKtQbGY0orf7OV1I50".getBytes(),
        "HmacSHA1");

Mac mac = Mac.getInstance("HmacSHA1");
mac.init(keySpec);
byte[] result = mac.doFinal("foo".getBytes());

BASE64Encoder encoder = new BASE64Encoder();
System.out.println(encoder.encode(result));
```

produces:

```
+3h2gpjf4xcynjCGU5lbdMBwGOc=
```

Note that I've used `sun.misc.BASE64Encoder` for a quick implementation here, but you should probably use something that doesn't depend on the Sun JRE. The base64-encoder in Commons Codec would be a better choice, for example.

How to generate an HMAC in Java equivalent to a Python example?

Solution

Problem