pgcrypto 0.4 - cryptographic functions for PostgreSQL.
======================================================
by Marko Kreen <marko@l-t.ee>
INSTALLATION
============
Edit makefile, if you want to use any external library.
NB! Default randomness source is libc random() function. This
is so only to get pgcrypto build everywhere. Randomness is
needed for gen_salt() function. So if you plan using it, you
should definitely change that by editing Makefile. You should
be using urandom device if your OS supports it, otherwise link
pgcrypto against OpenSSL library and use its PRNG.
After editing Makefile:
make
make install
To run regression tests, install both PostgreSQL and pgcrypto
and then run
make installcheck
SQL FUNCTIONS
=============
If any of arguments are NULL they return NULL.
digest(data::bytea, type::text)::bytea
Type is here the algorithm to use. E.g. 'md5', 'sha1', ...
Returns binary hash.
digest_exists(type::text)::bool
Returns BOOL whether given hash exists.
hmac(data::bytea, key::bytea, type::text)::bytea
Calculates Hashed MAC over data. type is the same as
in digest(). Returns binary hash. Similar to digest()
but noone can alter data and re-calculate hash without
knowing key. If the key is larger than hash blocksize
it will first hashed and the hash will be used as key.
[ HMAC is described in RFC2104. ]
hmac_exists(type::text)::bool
Returns BOOL. It is separate function because all hashes
cannot be used in HMAC.
crypt(password::text, salt::text)::text
Calculates UN*X crypt(3) style hash. Useful for storing
passwords. For generating salt you should use the
gen_salt() function. Usage:
New password:
UPDATE .. SET pswhash = crypt(new_psw, gen_salt('md5'));
Authentication:
SELECT pswhash = crypt(given_psw, pswhash) WHERE .. ;
returns BOOL whether the given_psw is correct. DES crypt
has max key of 8 bytes, MD5 has max key at least 2^32-1
bytes but may be larger on some platforms...
Builtin crypt() supports DES, Extended DES, MD5 and Blowfish
(variant 2a) algorithms.
gen_salt(type::text)::text
Generates a new random salt for usage in crypt(). Type
'des' - Old UNIX, not recommended
'md5' - md5-based crypt()
'xdes' - 'Extended DES'
'bf' - Blowfish-based, variant 2a
When you use --enable-system-crypt then note that system
libcrypt may not support them all.
gen_salt(type::text, rounds::int4)::text
same as above, but lets user specify iteration count
for algorithm. Number is algotithm specific:
type default min max
---------------------------------
xdes 725 1 16777215
bf 6 4 31
In case of xdes there is a additional limitation that the
count must be a odd number.
The higher the count, the more time it takes to calculate
crypt and therefore the more time to break it. But beware!
With too high count it takes a _very_long_ time to
calculate it.
For maximum security, you should choose the 'bf' crypt
and use maximum number of rounds you can still tolerate.
encrypt(data::bytea, key::bytea, type::text)::bytea
decrypt(data::bytea, key::bytea, type::text)::bytea
encrypt_iv(data::bytea, key::bytea, iv::bytea, type::text)::bytea
decrypt_iv(data::bytea, key::bytea, iv::bytea, type::text)::bytea
Encrypt/decrypt data with cipher, padding data if needed.
Pseudo-noteup:
algo ['-' mode] ['/pad:' padding]
Supported algorithms:
bf - Blowfish
aes, rijndael - Rijndael-128
Others depend on library and are not tested enough, so
play on your own risk.
Modes: 'cbc' (default), 'ecb'. Again, library may support
more.
Padding is 'pkcs' (default), 'none'. 'none' is mostly for
testing ciphers, you should not need it.
So, example:
encrypt(data, 'fooz', 'bf')
is equal to
encrypt(data, 'fooz', 'bf-cbc/pad:pkcs')
IV is initial value for mode, defaults to all zeroes.
It is ignored for ECB. It is clipped or padded with zeroes
if not exactly block size.
ALGORITHMS
==========
The standard functionality at the moment consist of
Hashes: md5, sha1
Ciphers: bf, aes
Modes: cbc, ecb
TODO: write stardard names for optional ciphers too.
LIBRARIES
=========
* crypt()
internal: des, xdes, md5, bf
-lcrypt: ??? (whatever you have)
* other:
[ This only list of stuff libraries claim to support. So
pgcrypto may work with all of them. But ATM tested aree only the
standard ciphers. On others pgcrypto and library may mess something
up. You have been warned. ]
internal (default):
Hashes: MD5, SHA1
Ciphers: Blowfish, Rijndael-128
OpenSSL (0.9.6):
Hashes: MD5, SHA1, RIPEMD160, MD2
Ciphers: DES, DESX, DES3, RC5, RC4, RC2, IDEA,
Blowfish, CAST5
License: BSD-like with strong advertisement
Url: http://www.openssl.org/
mhash (0.8.9) + mcrypt (2.4.16):
Hashes: MD5, SHA1, CRC32, CRC32B, GOST, TIGER, RIPEMD160,
HAVAL(256,224,192,160,128)
Ciphers: DES, DES3, CAST-128(CAST5), CAST-256, xTEA, 3-way,
SKIPJACK, Blowfish, Twofish, LOKI97, RC2, RC4, RC6,
Rijndael-128/192/256, MARS, PANAMA, WAKE, Serpent, IDEA, GOST,
SAFER, SAFER+, Enigma
License: LGPL
Url: http://mcrypt.sourceforge.org/
Url: http://mhash.sourceforge.org/
CREDITS
=======
I have used code from following sources:
DES crypt() by David Burren and others FreeBSD libcrypt
MD5 crypt() by Poul-Henning Kamp FreeBSD libcrypt
Blowfish crypt() by Solar Designer www.openwall.com
Blowfish cipher by Niels Provos OpenBSD sys/crypto
Rijndael cipher by Brian Gladman OpenBSD sys/crypto
MD5 and SHA1 by WIDE Project KAME kame/sys/crypto
LEGALESE
========
* I owe a beer to Poul-Henning.
* This product includes software developed by Niels Provos.
