From: Adam Back <aba@dcs.ex.ac.uk>
Date: Tue, 22 Sep 1998 18:16:32 +0800
To: cypherpunks@cyberpass.net
Subject: pgpacket bug (Re: CHALLENGE? Toto/signature attack w. unpublished public key)
In-Reply-To: <199809220108.DAA07731@replay.com>
Message-ID: <199809221857.TAA11080@server.eternity.org>
MIME-Version: 1.0
Content-Type: text/plain




Anonymous writes:
> This value is wrong: it has 3 bytes of 0's inserted and is therefore
> missing the last three bytes of the signature.
> 
> s =   0x08F4D5CBC10063725B206F787EB7370BBD0C5B4854CE79A9007D1801AEAEE6E6
>         D2C68D7EDF877FECE1FA539D08BEC54BD152BA05113951E8A84CDECAD2CB8E7A
>         C28BE916570BA7BB9C00C64DF57113C4AE81613BD351541523CD3A028FBF220E
>         F7469BD4175302DCB5B6E886974877F28A2D301433AFFFE26081008BFF687B37
> 
> 
> Here is the correct value, from the signed message.
> 
> 08F4D5CBC10063725B206F787EB7370BBD0C5B4854CE79A97D1801AEAEE6E6D2
> C68D7EDF877FECE1FA539D08BEC54BD152BA05113951E8A84CDECAD2CB8E7AC2
> 8BE916570BA7BB9CC64DF57113C4AE81613BD351541523CD3A028FBF220EF746
> 9BD4175302DCB5B6E886974877F28A2D301433AFFFE260818BFF687B37DE8167

Hmm!  That explains this output of pgpacket which I had already
forwarded to Mark Shoulson as a bug in pgpacket:

% pgpacket < totopost.asc
---------------------------
Packet Type:    Secret-Key Encrypted Packet (signature)
Length: 149
Version:        3
Adding 5 bytes of header to digest
Signature of canonical text document
Signature Created:      9 Dec 1997  21:29:02
Signing Key ID: 0xCE56A4072541C535
Public Key Algorithm:   1 (RSA)
Message Digest Algorithm:       1 (MD5)
Check bytes:    0x5A82
128 bytes of data (1)
Data:   08F4D5CBC10063725B206F787EB7370BBD0C5B4854CE79A9007D1801AEAEE6E6D2C68D7E
DF877FECE1FA539D08BEC54BD152BA05113951E8A84CDECAD2CB8E7AC28BE916570BA7BB9C00C64D
F57113C4AE81613BD351541523CD3A028FBF220EF7469BD4175302DCB5B6E886974877F28A2D3014
33AFFFE26081008BFF687B37

---------------------------
Packet Type:    UNKNOWN PACKET!! (36)
Length: 129
(No handler known.  Skipping 1 bytes)
Data:   0x67

I couldn't figure out what the spurious packet was about, you just
solved that one... pgpacket is inserting spurious 00s in the message.
(I've Cc'ed Mark Shoulson).

Adam