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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Derek Atkins wrote: > Tom Metro <blu-5a1Jt6qxUNc at public.gmane.org> writes: > >> Dan Ritter wrote: >>> Don Levey wrote: >>>> ...gpg generates its own key, encrypts the data with that, and then >>>> the recipient's public key is used to encrypt the data key... >>> In fact, this is what always happens, one recipient (R) or n recipients >>> R0..Rn. GPG makes a random key K, encrypts your message M with K, then >>> sends K(M) + R0(K) +... Rn(K). >> Right...because public key encryption is expensive (CPU intensive), so >> they use a symmetric cypher to encrypt the payload, and use PKI to >> encrypt just the symmetric key. > > Not only is public key encryption expensive in terms of CPU, it's also > extremely limited in the size of the message you can encrypt. If you > have a 2048-bit RSA key the message you can encrypt is less than 2K! > That rules out most messages. And when PGP first came out people were > using 512-bit keys. Imagine being limited to messages of under 60 > bytes. Not very useful. > > When PGP 2.0 was released in September, 1992, it could only encrypt a > message to a single recipient, even though it used this same Encrypted > Session Key (ESK) methodolgy. Multiple recipient support was added > shortly thereafter, but I don't recall if that made it into 2.1.1 or > 2.2 back in '92-93. > Interesting - I didn't know any of this. Thanks! -Don -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFI+J2CiVR8AmYXiFARAkphAJ90pL323D8rnGkcYg1iczdFqV3HggCfYlJs 4FtTTO2SwWYb3CWW3u/0Xlg= =B9Tj -----END PGP SIGNATURE-----
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