JCE: generateing HmacSHA1

[Timo Nentwig]

Hi!

I'm not very familiar with all the hashing and encrypting stuff.

I used to generate the hash (or MAC or whatever) with a Windows util called
HashCalc (google . I can enter the data to create the SHA1 from and I can
enter data for HMAC - and the latter is the problem. I didn' figure out how
this can be done with JCE.

Can somebody cast some light on the issue or is there a free alternative to
JCE?

Thanks
Timo

 

[Timo Nentwig]

I used to generate the hash (or MAC or whatever) with a Windows util
called HashCalc (google . I can enter the data to create the SHA1 from
and I can enter data for HMAC - and the latter is the problem. I didn'
figure out how this can be done with JCE.

Ok, in other words:

I can archieve what I want using the implemention of freenet.crypt:

final byte[] msg = Hex.decodeHex( "010a".toCharArray() );
final byte[] hmac = Hex.decodeHex( "090f".toCharArray() );

final HMAC s = new HMAC( SHA1.getInstance() );
byte[] mv = s.mac( hmac, msg, 20 );

for ( int i = 0; i < mv.length; i++ )
System.out.print( byte2hex( mv ) );

How do I implement the same with JCE?

 

[Timo Nentwig]

How do I implement the same with JCE?

final byte[] msg = "foo".getBytes();
final byte[] key = "bar".getBytes();

final SecretKeySpec hmac = new SecretKeySpec( key, "HmacSHA1" );

final Mac mac = Mac.getInstance( hmac.getAlgorithm() );
mac.init( hmac );

final byte[] digest = mac.doFinal( msg );