Fix BigInteger.modInverse DoS in shipped bundles

[Kr0emer]

Summary

Fix a denial-of-service issue in the shipped jsrsasign bundles where BigInteger.modInverse(0, odd_modulus) could enter an infinite loop.

What changed

• Synced bundled bnModInverse implementations with the normalized safe logic already present in source
• Updated the generated browser and npm bundles affected by the source/bundle desync
• Added a regression test covering modInverse(0, 9) through the npm entrypoint

Validation

• Reproduced the hang locally against npm/lib/jsrsasign.js with a timeout-based PoC before the fix
• Verified the fixed bundle now returns 0 instead of hanging
• Added and executed a regression test locally with a lightweight harness

[kjur]

Hi @Kr0emer , could you conclude ext/jsbn2.js with your fix? Thank you as always.

[Kr0emer]

Hi @Kr0emer , could you conclude ext/jsbn2.js with your fix? Thank you as always.
Sorry for the late response—I’ve been quite busy lately and missed your email. I’ve now pushed the requested changes. Thank you for your patience.