mcrypt selects a default from one of its possible encryption algorithms if one isn't explicitly named.
mcrypt --list shows all available algorithms, but doesn't mark which one is default. Neither encrypting nor decrypting a file output which algorithm is being used. So, how do I figure out the default?
The latest versions of
file will tell you the algorithm used on a file encrypted by
$ mcrypt foo.bar $ file foo.bar.nc foo.bar.nc: mcrypt 2.5 encrypted data, algorithm: rijndael-128, keysize: 32 bytes, mode: cbc,