PGP encryption: block or stream cipher?

Robert J. Hansen rjh at
Tue Nov 6 18:49:40 CET 2007

Jim Cook wrote:
> Does anyone know which type of cipher is used?

No.  Well, block ciphers, but beyond that nobody can tell you very much.

GnuPG supports a large number of block ciphers--probably too many.
Which cipher is used for a particular message depends on both your
preferences and your recipient's preferences.  GnuPG does a variant of
the stable-marriage problem to find a cipher that's mutually agreeable
to both you and your recipient.  So no, without knowing what your and
your recipient's preferences are, we really can't say which block
ciphers are used.

To see which ciphers your version of GnuPG supports, enter:

gpg --version

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