Re: [PATCH] pgcrypto: pgp_encrypt v3 - Mailing list pgsql-patches
From | Marko Kreen |
---|---|
Subject | Re: [PATCH] pgcrypto: pgp_encrypt v3 |
Date | |
Msg-id | 20050704110746.GA32159@l-t.ee Whole thread Raw |
In response to | [PATCH] pgcrypto: pgp_encrypt (Marko Kreen <marko@l-t.ee>) |
List | pgsql-patches |
Well, I needed to decide, whether it is realistic to implement PGP public-key encryption someday, because then I better rename the function 'pgp_encrypt' to something more specific immidiately. But after hacking a while, I soon had working implementation, so it seems silly to wait 8.2 for it. This is thanks to the fact that for encryption I can ignore most of the OpenPGP complex parts - signing and key-management. IMHO they don't even make sense inside database, they need an end-user application. In short, the goal of this code is not to be full OpenPGP implementation, but just provide more flexible encryption than the usual symmetric encryption. So here is updated pgp_encrypt patch, with support for both symmetric and public-key encryption. Also, as Neil requested, non-failing regression tests - unsupported parts are replaced with empty test named '*-DISABLED'. Note: it uses OpenSSL bignum code - so without OpenSSL no public-key encryption. Look below for plans for fixing this dependance. New names for symmetric-key functions: pgp_sym_encrypt(data, key) pgp_sym_decrypt(data, key) Public key functions: pgp_pub_encrypt(data, key) pgp_pub_decrypt(data, key) pgp_pub_decrypt(data, key, psw) Plus variants with 'arg' and for bytea. Not mentioned in previous mails: armor(bytea) -> text dearmor(text) -> bytea Apply and remove PGP Ascii Armor. Implemented featureѕ: * Elgamal-encryption keys - preferred public-key algo for OpenPGP. * Password-protected secret keys. Missing features (needs implementing ASAP): * pgp_key_id() - Function to query the ID of a key, and the key ID from encrypted packet - so user can implement key rings on his own. Maybe: * As it does not parse sign packets, it does not support recipient cipher preferences. It is not important for planned use-case, but maybe it would be nice to have. Does not support (and I see no need): * RSA-encrypt and sign+encrypt keys - they are deprecated in RFC, GnuPG does not even give option to generate them, so IMO it's fine to ignore them. * Picking a key from list of keys - accepting a keyring in place of key. * Several encryption subkeys under one key. * Any form of signing - that also means no key integrity checks (eg - does the subkey belong to master key). Now, the code is significant in the following respect - the module 'contrib/pgcrypto' is complete. As I said, I don't think rest of the OpenPGP makes sense here, and there isn't any other generally-useful crypto functionality that would be good to have. Still, there are various things to do: 1. Polishing of the new PGP code. 2. Rework documentation and add FAQ. 3. Try to extract OpenSSL and zlib settings from main PostgreSQL config. Basically that means that ./configure should put them to separate variables, not into main CFLAGS. 4. Include strong RNG. Yarrow, Fortuna, ?. This is for both symmetricy and public-key encryption. 5. Include bignum code (only ops needed for Elgamal). This is for public-key encrypt/decrypt. 6. Propose crypt(), gen_salt() into mainline for 8.2. They are self-contained, except crypt-md5 depends on a MD5 implentation, which already exists in mainline. Points 4 and 5 are suspicious - I'm not yet sure it can be done in manageable way. But without those, the PGP functions are unusable in default build. It may not be that bad - Yarrow/Fortuna seem to be small pieces only requiring external cipher and hash, which we have. And I could drop parts of libtommath into separate directory. But I don't think such things should be done in hurry. In the end, I think the code can go into 8.1 in current state - requiring OpenSSL. I'll look into dependencies in 8.2 timeframe. -- marko
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