Few on DSA

I was looking into Jira’s licensing and chose to patch + keygen jars.

I extracted the public key from class file, base64 decoded and then printed details using openssl:

This is a (1024,160) L/N pair, key size 1024 bits and length of Q is 160.

from http://en.wikipedia.org/wiki/Digital_Signature_Algorithm I learnt:

Per-user keys
Given a set of parameters, the second phase computes private and public keys for a single user:

Choose x by some random method, where 0 < x < q. Calculate y = gx mod p. Public key is (p, q, g, y). Private key is x. There exist efficient algorithms for computing the modular exponentiations h(p–1)/q mod p and gx mod p, such as exponentiation by squaring.

y is the PUB above, x is what I want.

I googled some lines in the public key and found this http://www.herongyang.com/Cryptography/keytool-Export-Key-openssl-dsa-Command.html, keys in Jira and this blog shares a same P/G/Q.
As it’s said in that blog, his key pair is generated by ‘keytool’, which is a key and certificate management tool provided by Java http://docs.oracle.com/javase/6/docs/technotes/tools/solaris/keytool.html

So I made an experiment:

A new key with the same P/G/Q.


Few on DSA by @sskaje: https://sskaje.me/2014/05/dsa/

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Jira Patched

Jira is awesome, I studied its registration and made a patch+keygen for fun. Here is what I get.
Jira Patched

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Jira Patched by @sskaje: https://sskaje.me/2014/04/jira-patched/