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208 lines
5.1 KiB
Plaintext
208 lines
5.1 KiB
Plaintext
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pgcrypto 0.4 - cryptographic functions for PostgreSQL.
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======================================================
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by Marko Kreen <marko@l-t.ee>
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INSTALLATION
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============
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Edit makefile, if you want to use any external library.
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NB! Default randomness source is libc random() function. This
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is so only to get pgcrypto build everywhere. Randomness is
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needed for gen_salt() function. So if you plan using it, you
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should definitely change that by editing Makefile. You should
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be using urandom device if your OS supports it, otherwise link
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pgcrypto against OpenSSL library and use its PRNG.
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After editing Makefile:
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make
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make install
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To run regression tests, install both PostgreSQL and pgcrypto
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and then run
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make installcheck
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SQL FUNCTIONS
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=============
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If any of arguments are NULL they return NULL.
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digest(data::bytea, type::text)::bytea
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Type is here the algorithm to use. E.g. 'md5', 'sha1', ...
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Returns binary hash.
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digest_exists(type::text)::bool
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Returns BOOL whether given hash exists.
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hmac(data::bytea, key::bytea, type::text)::bytea
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Calculates Hashed MAC over data. type is the same as
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in digest(). Returns binary hash. Similar to digest()
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but noone can alter data and re-calculate hash without
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knowing key. If the key is larger than hash blocksize
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it will first hashed and the hash will be used as key.
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[ HMAC is described in RFC2104. ]
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hmac_exists(type::text)::bool
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Returns BOOL. It is separate function because all hashes
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cannot be used in HMAC.
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crypt(password::text, salt::text)::text
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Calculates UN*X crypt(3) style hash. Useful for storing
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passwords. For generating salt you should use the
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gen_salt() function. Usage:
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New password:
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UPDATE .. SET pswhash = crypt(new_psw, gen_salt('md5'));
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Authentication:
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SELECT pswhash = crypt(given_psw, pswhash) WHERE .. ;
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returns BOOL whether the given_psw is correct. DES crypt
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has max key of 8 bytes, MD5 has max key at least 2^32-1
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bytes but may be larger on some platforms...
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Builtin crypt() supports DES, Extended DES, MD5 and Blowfish
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(variant 2a) algorithms.
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gen_salt(type::text)::text
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Generates a new random salt for usage in crypt(). Type
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'des' - Old UNIX, not recommended
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'md5' - md5-based crypt()
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'xdes' - 'Extended DES'
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'bf' - Blowfish-based, variant 2a
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When you use --enable-system-crypt then note that system
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libcrypt may not support them all.
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gen_salt(type::text, rounds::int4)::text
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same as above, but lets user specify iteration count
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for algorithm. Number is algorithm specific:
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type default min max
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---------------------------------
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xdes 725 1 16777215
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bf 6 4 31
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In case of xdes there is a additional limitation that the
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count must be a odd number.
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The higher the count, the more time it takes to calculate
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crypt and therefore the more time to break it. But beware!
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With too high count it takes a _very_long_ time to
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calculate it.
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For maximum security, you should choose the 'bf' crypt
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and use maximum number of rounds you can still tolerate.
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encrypt(data::bytea, key::bytea, type::text)::bytea
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decrypt(data::bytea, key::bytea, type::text)::bytea
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encrypt_iv(data::bytea, key::bytea, iv::bytea, type::text)::bytea
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decrypt_iv(data::bytea, key::bytea, iv::bytea, type::text)::bytea
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Encrypt/decrypt data with cipher, padding data if needed.
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Pseudo-noteup:
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algo ['-' mode] ['/pad:' padding]
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Supported algorithms:
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bf - Blowfish
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aes, rijndael - Rijndael-128
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Others depend on library and are not tested enough, so
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play on your own risk.
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Modes: 'cbc' (default), 'ecb'. Again, library may support
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more.
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Padding is 'pkcs' (default), 'none'. 'none' is mostly for
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testing ciphers, you should not need it.
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So, example:
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encrypt(data, 'fooz', 'bf')
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is equal to
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encrypt(data, 'fooz', 'bf-cbc/pad:pkcs')
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IV is initial value for mode, defaults to all zeroes.
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It is ignored for ECB. It is clipped or padded with zeroes
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if not exactly block size.
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ALGORITHMS
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==========
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The standard functionality at the moment consists of
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Hashes: md5, sha1
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Ciphers: bf, aes
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Modes: cbc, ecb
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TODO: write standard names for optional ciphers too.
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LIBRARIES
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=========
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* crypt()
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internal: des, xdes, md5, bf
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-lcrypt: ??? (whatever you have)
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* other:
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[ This only lists stuff that the libraries claim to support. So
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pgcrypto may work with all of them. But ATM tested are only the
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standard ciphers. On others pgcrypto and library may mess something
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up. You have been warned. ]
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internal (default):
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Hashes: MD5, SHA1
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Ciphers: Blowfish, Rijndael-128
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OpenSSL (0.9.7):
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Hashes: MD5, SHA1, RIPEMD160, MD2
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Ciphers: Blowfish, AES, CAST5, DES, 3DES
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License: BSD-like with strong advertisement
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Url: http://www.openssl.org/
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CREDITS
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=======
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I have used code from following sources:
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DES crypt() by David Burren and others FreeBSD libcrypt
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MD5 crypt() by Poul-Henning Kamp FreeBSD libcrypt
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Blowfish crypt() by Solar Designer www.openwall.com
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Blowfish cipher by Niels Provos OpenBSD sys/crypto
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Rijndael cipher by Brian Gladman OpenBSD sys/crypto
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MD5 and SHA1 by WIDE Project KAME kame/sys/crypto
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LEGALESE
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========
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* I owe a beer to Poul-Henning.
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* This product includes software developed by Niels Provos.
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