Extend PGP format?

[Yoshioka Tsuneo]

Dear GNUpg Developers.

 I want to make software that can seek encrypted file. 
But PGP file is encrypted by CFB mode. So I must read from the top of a
file. It's too late. Is there any way to search firstly?

 If there is no way now, I'll try to extend PGP file like under way.

1. use ECB mode to encode. 
2. separate Symmetrically Encrypted Data Packet to several small
packets. File format will be under image.

Encrypted Session Key for user1
Encrypted Session Key for user2
.....
Symmetric-Key Encrypted Session Key Packet part1
Symmetric-Key Encrypted Session Key Packet part2
Symmetric-Key Encrypted Session Key Packet part3
Symmetric-Key Encrypted Session Key Packet part4
(* Symmetric-Key Encrypted Session Key Packet use the same Encrypted
Session Key)

Is there any problem or suggestion about this format?

Thank you.

Yoshioka Tsuneo(yoshioka at xaxon.co.jp)