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Add missing pgcrypto files from previous commit.
This commit is contained in:
Bruce Momjian
365
contrib/pgcrypto/fortuna.c
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365
contrib/pgcrypto/fortuna.c
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/*
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* fortuna.c
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* Fortuna-like PRNG.
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*
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* Copyright (c) 2005 Marko Kreen
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $PostgreSQL: pgsql/contrib/pgcrypto/fortuna.c,v 1.1 2005/07/10 13:46:27 momjian Exp $
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*/
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#include <postgres.h>
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#include <sys/time.h>
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#include <time.h>
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#include "rijndael.h"
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#include "sha2.h"
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#include "fortuna.h"
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/*
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* Why Fortuna-like: There does not seem to be any definitive reference
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* on Fortuna in the net. Instead this implementation is based on
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* following references:
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*
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* http://en.wikipedia.org/wiki/Fortuna_(PRNG)
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* - Wikipedia article
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* http://jlcooke.ca/random/
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* - Jean-Luc Cooke Fortuna-based /dev/random driver for Linux.
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*/
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/*
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* There is some confusion about whether and how to carry forward
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* the state of the pools. Seems like original Fortuna does not
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* do it, resetting hash after each request. I guess expecting
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* feeding to happen more often that requesting. This is absolutely
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* unsuitable for pgcrypto, as nothing asynchronous happens here.
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*
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* J.L. Cooke fixed this by feeding previous hash to new re-initialized
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* hash context.
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*
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* Fortuna predecessor Yarrow requires ability to query intermediate
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* 'final result' from hash, without affecting it.
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*
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* This implementation uses the Yarrow method - asking intermediate
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* results, but continuing with old state.
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*/
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/*
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* Algorithm parameters
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*/
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/*
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* How many pools.
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*
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* Original Fortuna uses 32 pools, that means 32'th pool is
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* used not earlier than in 13th year. This is a waste in
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* pgcrypto, as we have very low-frequancy seeding. Here
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* is preferable to have all entropy usable in reasonable time.
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*
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* With 23 pools, 23th pool is used after 9 days which seems
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* more sane.
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*
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* In our case the minimal cycle time would be bit longer
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* than the system-randomness feeding frequency.
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*/
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#define NUM_POOLS 23
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/* in microseconds */
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#define RESEED_INTERVAL 100000 /* 0.1 sec */
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/* for one big request, reseed after this many bytes */
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#define RESEED_BYTES (1024*1024)
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/*
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* Algorithm constants
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*/
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/* max sources */
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#define MAX_SOURCES 8
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/* Both cipher key size and hash result size */
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#define BLOCK 32
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/* cipher block size */
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#define CIPH_BLOCK 16
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/* for internal wrappers */
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#define MD_CTX SHA256_CTX
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#define CIPH_CTX rijndael_ctx
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struct fortuna_state {
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uint8 counter[CIPH_BLOCK];
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uint8 result[CIPH_BLOCK];
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uint8 key[BLOCK];
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MD_CTX pool[NUM_POOLS];
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CIPH_CTX ciph;
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unsigned source_pos[MAX_SOURCES];
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unsigned reseed_count;
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struct timeval last_reseed_time;
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};
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typedef struct fortuna_state FState;
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/*
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* Use our own wrappers here.
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* - Need to get intermediate result from digest, without affecting it.
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* - Need re-set key on a cipher context.
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* - Algorithms are guaranteed to exist.
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* - No memory allocations.
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*/
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static void ciph_init(CIPH_CTX *ctx, const uint8 *key, int klen)
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{
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rijndael_set_key(ctx, (const uint32 *)key, klen, 1);
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}
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static void ciph_encrypt(CIPH_CTX *ctx, const uint8 *in, uint8 *out)
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{
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rijndael_encrypt(ctx, (const uint32 *)in, (uint32 *)out);
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}
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static void md_init(MD_CTX *ctx)
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{
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SHA256_Init(ctx);
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}
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static void md_update(MD_CTX *ctx, const uint8 *data, int len)
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{
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SHA256_Update(ctx, data, len);
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}
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static void md_result(MD_CTX *ctx, uint8 *dst)
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{
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SHA256_CTX tmp;
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memcpy(&tmp, ctx, sizeof(*ctx));
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SHA256_Final(dst, &tmp);
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memset(&tmp, 0, sizeof(tmp));
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}
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/*
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* initialize state
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*/
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static void init_state(FState *st)
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{
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int i;
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memset(st, 0, sizeof(*st));
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for (i = 0; i < NUM_POOLS; i++)
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md_init(&st->pool[i]);
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}
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/*
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* Must not reseed more ofter than RESEED_PER_SEC
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* times per second.
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*/
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static int too_often(FState *st)
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{
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int ok;
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struct timeval tv;
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struct timeval *last = &st->last_reseed_time;
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gettimeofday(&tv, NULL);
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ok = 0;
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if (tv.tv_sec != last->tv_sec)
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ok = 1;
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else if (tv.tv_usec - last->tv_usec >= RESEED_INTERVAL)
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ok = 1;
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memcpy(last, &tv, sizeof(tv));
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memset(&tv, 0, sizeof(tv));
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return ok;
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}
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/*
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* generate new key from all the pools
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*/
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static void reseed(FState *st)
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{
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unsigned k;
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unsigned n;
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MD_CTX key_md;
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uint8 buf[BLOCK];
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/* check frequency */
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if (too_often(st))
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return;
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/*
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* Both #0 and #1 reseed would use only pool 0.
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* Just skip #0 then.
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*/
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n = ++st->reseed_count;
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/*
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* The goal: use k-th pool only 1/(2^k) of the time.
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*/
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md_init(&key_md);
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for (k = 0; k < NUM_POOLS; k++) {
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md_result(&st->pool[k], buf);
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md_update(&key_md, buf, BLOCK);
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if (n & 1 || !n)
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break;
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n >>= 1;
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}
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/* add old key into mix too */
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md_update(&key_md, st->key, BLOCK);
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/* now we have new key */
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md_result(&key_md, st->key);
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/* use new key */
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ciph_init(&st->ciph, st->key, BLOCK);
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memset(&key_md, 0, sizeof(key_md));
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memset(buf, 0, BLOCK);
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n = k = 0;
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}
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/*
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* update pools
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*/
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static void add_entropy(FState *st, unsigned src_id, const uint8 *data, unsigned len)
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{
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unsigned pos;
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uint8 hash[BLOCK];
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MD_CTX md;
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/* just in case there's a bug somewhere */
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if (src_id >= MAX_SOURCES)
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src_id = USER_ENTROPY;
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/* hash given data */
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md_init(&md);
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md_update(&md, data, len);
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md_result(&md, hash);
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/* update pools round-robin manner */
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pos = st->source_pos[src_id];
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md_update( &st->pool[pos], hash, BLOCK);
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if (++pos >= NUM_POOLS)
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pos = 0;
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st->source_pos[src_id] = pos;
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memset(hash, 0, BLOCK);
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memset(&md, 0, sizeof(md));
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}
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/*
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* Endianess does not matter.
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* It just needs to change without repeating.
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*/
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static void inc_counter(FState *st)
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{
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uint32 *val = (uint32*)st->counter;
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if (++val[0])
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return;
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if (++val[1])
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return;
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if (++val[2])
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return;
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++val[3];
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}
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static void extract_data(FState *st, unsigned count, uint8 *dst)
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{
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unsigned n;
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unsigned block_nr = 0;
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/*
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* Every request should be with different key,
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* if possible.
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*/
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reseed(st);
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/*
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* If the reseed didn't happen, don't use the old data
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* rather encrypt again.
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*/
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while (count > 0) {
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/* must not give out too many bytes with one key */
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if (block_nr > (RESEED_BYTES / CIPH_BLOCK))
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{
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reseed(st);
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block_nr = 0;
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}
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/* produce bytes */
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ciph_encrypt(&st->ciph, st->counter, st->result);
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block_nr++;
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/* prepare for next time */
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inc_counter(st);
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/* copy result */
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if (count > CIPH_BLOCK)
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n = CIPH_BLOCK;
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else
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n = count;
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memcpy(dst, st->result, n);
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dst += n;
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count -= n;
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}
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}
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/*
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* public interface
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*/
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static FState main_state;
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static int init_done = 0;
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void fortuna_add_entropy(unsigned src_id, const uint8 *data, unsigned len)
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{
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if (!init_done)
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{
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init_state(&main_state);
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init_done = 1;
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}
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if (!data || !len)
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return;
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add_entropy(&main_state, src_id, data, len);
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}
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void fortuna_get_bytes(unsigned len, uint8 *dst)
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{
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if (!init_done)
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{
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init_state(&main_state);
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init_done = 1;
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}
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if (!dst || !len)
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return;
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extract_data(&main_state, len, dst);
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}
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