GPG/PGP5 encryption

brian moore bem at
Sat Oct 24 17:16:48 CEST 1998

On Sat, Oct 24, 1998 at 03:15:36PM -0700, brian moore wrote:
> Looks like I need to make a subkey to appease PGP5.

Nope, hurdle one: PGP5 hates zlib.  So 'compress-algo 1' helps greatly.

With PGP5 -> PGP5:
[thorin:~] 3:57:54pm 363 % echo "hi there" | pgpe -r 0x272B34B6 -f -sa |
pgpv -f -m

(pgpe's output snipped):

Message is encrypted.
Need a pass phrase to decrypt private key:
  1024 bits, Key ID 272B34B6, Created 1998-10-17
Enter pass phrase: 
Pass phrase is good.
Opening file "_CONSOLE" type binary.

Plaintext message follows...

hi there

Done...hit any key

Good signature made 1998-10-24 22:58 GMT by key:
  1024 bits, Key ID 40714B53, Created 1998-10-24
   "testing <bem at>"

The packets, with gpg --list-packets replacing the pgpv:

:pubkey enc packet: version 3, algo 16, keyid C12FC700272B34B6
        data: [1022 bits]
        data: [1022 bits]
:encrypted data packet:
        length: 104
dat: encrypted data
:compressed packet: algo=1
:onepass_sig packet: keyid 06119D7340714B53
        version 3, sigclass 00, digest 2, pubkey 17, last=1
:literal data packet:
        mode b, created 134217728, name="stdin",
        raw data: 9 bytes
:signature packet: algo 17, keyid 06119D7340714B53
        version 3, created 909269867, md5len 5, sigclass 00
        digest algo 2, begin of digest ee 01
        data: [158 bits]
        data: [160 bits]

Note the one-pass sig.

gpg doesn't seem to generate them 'old_style' is set.  I'm not sure why,
since PGP5 does version 3 packets and one-pass.

Forcing zip instead of zlib does let the encryption work fine with pgp5,
it's just the signing that PGP5 can't handle.

Brian Moore                       | "The Zen nature of a spammer resembles
      Sysadmin, C/Perl Hacker     |  a cockroach, except that the cockroach
      Usenet Vandal               |  is higher up on the evolutionary chain."
      Netscum, Bane of Elves.                 Peter Olson, Delphi Postmaster

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