Recently I came across a problem. My friend could not decrypt the channel message in IRC as the channel has a blowfish key exceeds 56 bytes of size. I don’t know about the mIRC implementation (fish10) but in weechat under Linux, I found a solution.
The core is to not use pycrypto. The default fish.py script in weechat is limited by pycrypto’s limit of 56 bytes, where blowfish key standard is up to 72 bytes long.
The above repository modifies the built-in fish.py to use the original FISH blowfish cipher rather than pycrypto.
1. Clone the repository
make to build the binary
make install to install it to your home
4. If you want to autoload it, move the fish.py and blowfish.so files to
Now you’ll be able to use 72 bytes key size to decrypt blowfish messages!