Using symmettric keys in GPG
Per Tunedal Casual
pt at radvis.nu
Fri Jun 11 09:23:31 CEST 2004
At 09:21 2004-06-09, you wrote:
>I want to use GPG in our office, and want to use symmetric encryption for
>sending files.. The reason being the files are too big (> 400 MB) and to
>encrypt them using public-key becomes too slow.
Be sure to use a symmetric crypto algo with 128-bit block size to encrypt
that large files because of the "birthday paradox". Otherwise the
probability of finding two identical blocks in the encrypted file is too
large, se previous discussion "twofish keysize", "Blocksize versus file
size" and "block-cipher weakness?".
Use AES, AES192, AES256 or TWOFISH. If you would like a large key size
TWOFISH is faster than AES256. AES is faster than TWOFISH, because TWOFISH
is always used with a 256 bit key. I haven't compared AES192 and TWOFISH
but they would probably perform similarly.
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