diff options
Diffstat (limited to 'libtomcrypt/src/prngs/fortuna.c')
| -rw-r--r-- | libtomcrypt/src/prngs/fortuna.c | 427 |
1 files changed, 427 insertions, 0 deletions
diff --git a/libtomcrypt/src/prngs/fortuna.c b/libtomcrypt/src/prngs/fortuna.c new file mode 100644 index 0000000..159db52 --- /dev/null +++ b/libtomcrypt/src/prngs/fortuna.c @@ -0,0 +1,427 @@ +/* LibTomCrypt, modular cryptographic library -- Tom St Denis + * + * LibTomCrypt is a library that provides various cryptographic + * algorithms in a highly modular and flexible manner. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com + */ +#include "tomcrypt.h" + +/** + @file fortuna.c + Fortuna PRNG, Tom St Denis +*/ + +/* Implementation of Fortuna by Tom St Denis + +We deviate slightly here for reasons of simplicity [and to fit in the API]. First all "sources" +in the AddEntropy function are fixed to 0. Second since no reliable timer is provided +we reseed automatically when len(pool0) >= 64 or every FORTUNA_WD calls to the read function */ + +#ifdef FORTUNA + +/* requries SHA256 and AES */ +#if !(defined(RIJNDAEL) && defined(SHA256)) + #error FORTUNA requires SHA256 and RIJNDAEL (AES) +#endif + +#ifndef FORTUNA_POOLS + #warning FORTUNA_POOLS was not previously defined (old headers?) + #define FORTUNA_POOLS 32 +#endif + +#if FORTUNA_POOLS < 4 || FORTUNA_POOLS > 32 + #error FORTUNA_POOLS must be in [4..32] +#endif + +const struct ltc_prng_descriptor fortuna_desc = { + "fortuna", 1024, + &fortuna_start, + &fortuna_add_entropy, + &fortuna_ready, + &fortuna_read, + &fortuna_done, + &fortuna_export, + &fortuna_import, + &fortuna_test +}; + +/* update the IV */ +static void fortuna_update_iv(prng_state *prng) +{ + int x; + unsigned char *IV; + /* update IV */ + IV = prng->fortuna.IV; + for (x = 0; x < 16; x++) { + IV[x] = (IV[x] + 1) & 255; + if (IV[x] != 0) break; + } +} + +/* reseed the PRNG */ +static int fortuna_reseed(prng_state *prng) +{ + unsigned char tmp[MAXBLOCKSIZE]; + hash_state md; + int err, x; + + ++prng->fortuna.reset_cnt; + + /* new K == SHA256(K || s) where s == SHA256(P0) || SHA256(P1) ... */ + sha256_init(&md); + if ((err = sha256_process(&md, prng->fortuna.K, 32)) != CRYPT_OK) { + sha256_done(&md, tmp); + return err; + } + + for (x = 0; x < FORTUNA_POOLS; x++) { + if (x == 0 || ((prng->fortuna.reset_cnt >> (x-1)) & 1) == 0) { + /* terminate this hash */ + if ((err = sha256_done(&prng->fortuna.pool[x], tmp)) != CRYPT_OK) { + sha256_done(&md, tmp); + return err; + } + /* add it to the string */ + if ((err = sha256_process(&md, tmp, 32)) != CRYPT_OK) { + sha256_done(&md, tmp); + return err; + } + /* reset this pool */ + if ((err = sha256_init(&prng->fortuna.pool[x])) != CRYPT_OK) { + sha256_done(&md, tmp); + return err; + } + } else { + break; + } + } + + /* finish key */ + if ((err = sha256_done(&md, prng->fortuna.K)) != CRYPT_OK) { + return err; + } + if ((err = rijndael_setup(prng->fortuna.K, 32, 0, &prng->fortuna.skey)) != CRYPT_OK) { + return err; + } + fortuna_update_iv(prng); + + /* reset pool len */ + prng->fortuna.pool0_len = 0; + prng->fortuna.wd = 0; + + +#ifdef LTC_CLEAN_STACK + zeromem(&md, sizeof(md)); + zeromem(tmp, sizeof(tmp)); +#endif + + return CRYPT_OK; +} + +/** + Start the PRNG + @param prng [out] The PRNG state to initialize + @return CRYPT_OK if successful +*/ +int fortuna_start(prng_state *prng) +{ + int err, x, y; + unsigned char tmp[MAXBLOCKSIZE]; + + LTC_ARGCHK(prng != NULL); + + /* initialize the pools */ + for (x = 0; x < FORTUNA_POOLS; x++) { + if ((err = sha256_init(&prng->fortuna.pool[x])) != CRYPT_OK) { + for (y = 0; y < x; y++) { + sha256_done(&prng->fortuna.pool[y], tmp); + } + return err; + } + } + prng->fortuna.pool_idx = prng->fortuna.pool0_len = prng->fortuna.wd = 0; + prng->fortuna.reset_cnt = 0; + + /* reset bufs */ + zeromem(prng->fortuna.K, 32); + if ((err = rijndael_setup(prng->fortuna.K, 32, 0, &prng->fortuna.skey)) != CRYPT_OK) { + for (x = 0; x < FORTUNA_POOLS; x++) { + sha256_done(&prng->fortuna.pool[x], tmp); + } + return err; + } + zeromem(prng->fortuna.IV, 16); + + LTC_MUTEX_INIT(&prng->fortuna.prng_lock) + + return CRYPT_OK; +} + +/** + Add entropy to the PRNG state + @param in The data to add + @param inlen Length of the data to add + @param prng PRNG state to update + @return CRYPT_OK if successful +*/ +int fortuna_add_entropy(const unsigned char *in, unsigned long inlen, prng_state *prng) +{ + unsigned char tmp[2]; + int err; + + LTC_ARGCHK(in != NULL); + LTC_ARGCHK(prng != NULL); + + LTC_MUTEX_LOCK(&prng->fortuna.prng_lock); + + /* ensure inlen <= 32 */ + if (inlen > 32) { + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return CRYPT_INVALID_ARG; + } + + /* add s || length(in) || in to pool[pool_idx] */ + tmp[0] = 0; + tmp[1] = (unsigned char)inlen; + if ((err = sha256_process(&prng->fortuna.pool[prng->fortuna.pool_idx], tmp, 2)) != CRYPT_OK) { + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return err; + } + if ((err = sha256_process(&prng->fortuna.pool[prng->fortuna.pool_idx], in, inlen)) != CRYPT_OK) { + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return err; + } + if (prng->fortuna.pool_idx == 0) { + prng->fortuna.pool0_len += inlen; + } + if (++(prng->fortuna.pool_idx) == FORTUNA_POOLS) { + prng->fortuna.pool_idx = 0; + } + + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return CRYPT_OK; +} + +/** + Make the PRNG ready to read from + @param prng The PRNG to make active + @return CRYPT_OK if successful +*/ +int fortuna_ready(prng_state *prng) +{ + return fortuna_reseed(prng); +} + +/** + Read from the PRNG + @param out Destination + @param outlen Length of output + @param prng The active PRNG to read from + @return Number of octets read +*/ +unsigned long fortuna_read(unsigned char *out, unsigned long outlen, prng_state *prng) +{ + unsigned char tmp[16]; + int err; + unsigned long tlen; + + LTC_ARGCHK(out != NULL); + LTC_ARGCHK(prng != NULL); + + LTC_MUTEX_LOCK(&prng->fortuna.prng_lock); + + /* do we have to reseed? */ + if (++prng->fortuna.wd == FORTUNA_WD || prng->fortuna.pool0_len >= 64) { + if ((err = fortuna_reseed(prng)) != CRYPT_OK) { + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return 0; + } + } + + /* now generate the blocks required */ + tlen = outlen; + + /* handle whole blocks without the extra XMEMCPY */ + while (outlen >= 16) { + /* encrypt the IV and store it */ + rijndael_ecb_encrypt(prng->fortuna.IV, out, &prng->fortuna.skey); + out += 16; + outlen -= 16; + fortuna_update_iv(prng); + } + + /* left over bytes? */ + if (outlen > 0) { + rijndael_ecb_encrypt(prng->fortuna.IV, tmp, &prng->fortuna.skey); + XMEMCPY(out, tmp, outlen); + fortuna_update_iv(prng); + } + + /* generate new key */ + rijndael_ecb_encrypt(prng->fortuna.IV, prng->fortuna.K , &prng->fortuna.skey); fortuna_update_iv(prng); + rijndael_ecb_encrypt(prng->fortuna.IV, prng->fortuna.K+16, &prng->fortuna.skey); fortuna_update_iv(prng); + if ((err = rijndael_setup(prng->fortuna.K, 32, 0, &prng->fortuna.skey)) != CRYPT_OK) { + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return 0; + } + +#ifdef LTC_CLEAN_STACK + zeromem(tmp, sizeof(tmp)); +#endif + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return tlen; +} + +/** + Terminate the PRNG + @param prng The PRNG to terminate + @return CRYPT_OK if successful +*/ +int fortuna_done(prng_state *prng) +{ + int err, x; + unsigned char tmp[32]; + + LTC_ARGCHK(prng != NULL); + LTC_MUTEX_LOCK(&prng->fortuna.prng_lock); + + /* terminate all the hashes */ + for (x = 0; x < FORTUNA_POOLS; x++) { + if ((err = sha256_done(&(prng->fortuna.pool[x]), tmp)) != CRYPT_OK) { + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return err; + } + } + /* call cipher done when we invent one ;-) */ + +#ifdef LTC_CLEAN_STACK + zeromem(tmp, sizeof(tmp)); +#endif + + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return CRYPT_OK; +} + +/** + Export the PRNG state + @param out [out] Destination + @param outlen [in/out] Max size and resulting size of the state + @param prng The PRNG to export + @return CRYPT_OK if successful +*/ +int fortuna_export(unsigned char *out, unsigned long *outlen, prng_state *prng) +{ + int x, err; + hash_state *md; + + LTC_ARGCHK(out != NULL); + LTC_ARGCHK(outlen != NULL); + LTC_ARGCHK(prng != NULL); + + LTC_MUTEX_LOCK(&prng->fortuna.prng_lock); + + /* we'll write bytes for s&g's */ + if (*outlen < 32*FORTUNA_POOLS) { + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + *outlen = 32*FORTUNA_POOLS; + return CRYPT_BUFFER_OVERFLOW; + } + + md = XMALLOC(sizeof(hash_state)); + if (md == NULL) { + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return CRYPT_MEM; + } + + /* to emit the state we copy each pool, terminate it then hash it again so + * an attacker who sees the state can't determine the current state of the PRNG + */ + for (x = 0; x < FORTUNA_POOLS; x++) { + /* copy the PRNG */ + XMEMCPY(md, &(prng->fortuna.pool[x]), sizeof(*md)); + + /* terminate it */ + if ((err = sha256_done(md, out+x*32)) != CRYPT_OK) { + goto LBL_ERR; + } + + /* now hash it */ + if ((err = sha256_init(md)) != CRYPT_OK) { + goto LBL_ERR; + } + if ((err = sha256_process(md, out+x*32, 32)) != CRYPT_OK) { + goto LBL_ERR; + } + if ((err = sha256_done(md, out+x*32)) != CRYPT_OK) { + goto LBL_ERR; + } + } + *outlen = 32*FORTUNA_POOLS; + err = CRYPT_OK; + +LBL_ERR: +#ifdef LTC_CLEAN_STACK + zeromem(md, sizeof(*md)); +#endif + XFREE(md); + LTC_MUTEX_UNLOCK(&prng->fortuna.prng_lock); + return err; +} + +/** + Import a PRNG state + @param in The PRNG state + @param inlen Size of the state + @param prng The PRNG to import + @return CRYPT_OK if successful +*/ +int fortuna_import(const unsigned char *in, unsigned long inlen, prng_state *prng) +{ + int err, x; + + LTC_ARGCHK(in != NULL); + LTC_ARGCHK(prng != NULL); + + if (inlen != 32*FORTUNA_POOLS) { + return CRYPT_INVALID_ARG; + } + + if ((err = fortuna_start(prng)) != CRYPT_OK) { + return err; + } + for (x = 0; x < FORTUNA_POOLS; x++) { + if ((err = fortuna_add_entropy(in+x*32, 32, prng)) != CRYPT_OK) { + return err; + } + } + return err; +} + +/** + PRNG self-test + @return CRYPT_OK if successful, CRYPT_NOP if self-testing has been disabled +*/ +int fortuna_test(void) +{ +#ifndef LTC_TEST + return CRYPT_NOP; +#else + int err; + + if ((err = sha256_test()) != CRYPT_OK) { + return err; + } + return rijndael_test(); +#endif +} + +#endif + + +/* $Source: /cvs/libtom/libtomcrypt/src/prngs/fortuna.c,v $ */ +/* $Revision: 1.12 $ */ +/* $Date: 2006/12/04 21:34:03 $ */ |