Decrypting a PGP 6.5.8 message fails

[disastry@saiknes.lv]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

> I tried to decrypt a message I've got from someone who uses PGP 6.5.8. 
> However it failed:
> 
> - ---
> gpg: cipher algorithm 1 is unknown or disabled
> gpg: encrypted with 1024-bit ELG-E key, ID xxxxxxxx, created xxxx-xx-xx

cipher 1 is IDEA
GPG does not support IDEA by default
you need IDEA module for GPG

== <EOF> ==
Disastry  http://i.am/disastry/
http://disastry.dhs.org/pgp <----PGP plugins for Netscape and MDaemon
 ^--GPG for Win32 (supports loadable modules and IDEA)
 ^---PGP 2.6.3ia-multi03 (supports IDEA, CAST5, BLOWFISH, TWOFISH,
     AES, 3DES ciphers and MD5, SHA1, RIPEMD160 hashes)
-----BEGIN PGP SIGNATURE-----
Version: Netscape PGP half-Plugin 0.15 by Disastry / PGPsdk v1.7.1

iQA/AwUBOt25jDBaTVEuJQxkEQJHewCeIwODG3rnvoG4YrtnG3DYZ8zHyH8AoJ++
ufeGN2H9z+pB2UwaQook7j1i
=pPMv
-----END PGP SIGNATURE-----