Multiple Sym. Encrypted Packets
Peter S. May
me at psmay.com
Tue Nov 7 18:45:18 CET 2006
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My thinking is that this isn't so much a problem with packet formats as
general syntax. It sounds like you're trying to put two distinct
OpenPGP messages into the same file. The section "OpenPGP Messages"
(10.3 in RFC2440-bis-18) in the spec defines the orders of packets that
make sense. If you've taken a compiler design course or know how to use
yacc/bison, it's straightforward to find that [PKESK][SED][PKESK][SED]
and [PKESK][PKESK][SED][SED] are not syntactically valid.
If you want your stream to contain multiple OpenPGP messages, you'll
have to figure out how to do it outside of OpenPGP proper.
Emlyn Jones wrote:
> I've written some code to generate an encrypted message which I can
> successfully decrypt using gpg. Currently the packet stream contains
> one Public-Key Encrypted Session Key Packet and one Symmetrically
> Encrypted Data Packet and works perfectly. However, I would like to
> set up the packet stream to contain multiple pairs of these packets.
> When I try it gpg fails to correctly read the packet immediately
> following the SED packet (it finds an invalid packet). Am I making
> This works:
> as does this:
> [PKESK] [PKESK][SED]
> This doesn't:
> [PKESK][SED][PKESK][SED] (fails reading the second PKESK)
> This will read the two PKESK packets and the first SED but not the final
> I have two questions:
> i)Should this be possible?
> ii)Are there any tools (other than gpg -vvv) to help debug what gpg
> is finding in my packet stream?
> iii)I'm pretty confident the size of the SED packet is specified
> correctly but do I need to make sure that the SED packet size is a
> multiple of the algorithm's block size?
> Any pointers gratefully received.
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