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Diffstat (limited to 'src/prng.c')
| -rw-r--r-- | src/prng.c | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/src/prng.c b/src/prng.c new file mode 100644 index 0000000..72c9305 --- /dev/null +++ b/src/prng.c @@ -0,0 +1,252 @@ +/* + * prng.c: Pseudo Random Number Generator abstractions for nwipe. + * + * Copyright Darik Horn <dajhorn-dban@vanadac.com>. + * + * This program is free software; you can redistribute it and/or modify it under + * the terms of the GNU General Public License as published by the Free Software + * Foundation, version 2. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS + * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more + * details. + * + * You should have received a copy of the GNU General Public License along with + * this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#include "nwipe.h" +#include "prng.h" +#include "context.h" +#include "logging.h" + +#include "mt19937ar-cok/mt19937ar-cok.h" +#include "isaac_rand/isaac_rand.h" +#include "isaac_rand/isaac64.h" + +nwipe_prng_t nwipe_twister = { "Mersenne Twister (mt19937ar-cok)", nwipe_twister_init, nwipe_twister_read }; + +nwipe_prng_t nwipe_isaac = { "ISAAC (rand.c 20010626)", nwipe_isaac_init, nwipe_isaac_read }; +nwipe_prng_t nwipe_isaac64 = { "ISAAC-64 (isaac64.c)", nwipe_isaac64_init, nwipe_isaac64_read }; + +/* Print given number of bytes from unsigned integer number to a byte stream buffer starting with low-endian. */ +static inline void u32_to_buffer( u8* restrict buffer, u32 val, const int len ) +{ + for( int i = 0; i < len; ++i ) + { + buffer[i] = ( u8 )( val & 0xFFUL ); + val >>= 8; + } +} +static inline void u64_to_buffer( u8* restrict buffer, u64 val, const int len ) +{ + for( int i = 0; i < len; ++i ) + { + buffer[i] = ( u8 )( val & 0xFFULL ); + val >>= 8; + } +} +static inline u32 isaac_nextval( randctx* restrict ctx ) +{ + if( ctx->randcnt == 0 ) + { + isaac( ctx ); + ctx->randcnt = RANDSIZ; + } + ctx->randcnt--; + return ctx->randrsl[ctx->randcnt]; +} +static inline u64 isaac64_nextval( rand64ctx* restrict ctx ) +{ + if( ctx->randcnt == 0 ) + { + isaac64( ctx ); + ctx->randcnt = RANDSIZ; + } + ctx->randcnt--; + return ctx->randrsl[ctx->randcnt]; +} + +int nwipe_twister_init( NWIPE_PRNG_INIT_SIGNATURE ) +{ + nwipe_log( NWIPE_LOG_NOTICE, "Initialising Mersenne Twister prng" ); + + if( *state == NULL ) + { + /* This is the first time that we have been called. */ + *state = malloc( sizeof( twister_state_t ) ); + } + twister_init( (twister_state_t*) *state, (u32*) ( seed->s ), seed->length / sizeof( u32 ) ); + return 0; +} + +int nwipe_twister_read( NWIPE_PRNG_READ_SIGNATURE ) +{ + u8* restrict bufpos = buffer; + size_t words = count / SIZE_OF_TWISTER; // the values of twister_genrand_int32 is strictly 4 bytes + + /* Twister returns 4-bytes per call, so progress by 4 bytes. */ + for( size_t ii = 0; ii < words; ++ii ) + { + u32_to_buffer( bufpos, twister_genrand_int32( (twister_state_t*) *state ), SIZE_OF_TWISTER ); + bufpos += SIZE_OF_TWISTER; + } + + /* If there is some remainder copy only relevant number of bytes to not + * overflow the buffer. */ + const size_t remain = count % SIZE_OF_TWISTER; // SIZE_OF_TWISTER is strictly 4 bytes + if( remain > 0 ) + { + u32_to_buffer( bufpos, twister_genrand_int32( (twister_state_t*) *state ), remain ); + } + + return 0; +} + +int nwipe_isaac_init( NWIPE_PRNG_INIT_SIGNATURE ) +{ + int count; + randctx* isaac_state = *state; + + nwipe_log( NWIPE_LOG_NOTICE, "Initialising Isaac prng" ); + + if( *state == NULL ) + { + /* This is the first time that we have been called. */ + *state = malloc( sizeof( randctx ) ); + isaac_state = *state; + + /* Check the memory allocation. */ + if( isaac_state == 0 ) + { + nwipe_perror( errno, __FUNCTION__, "malloc" ); + nwipe_log( NWIPE_LOG_FATAL, "Unable to allocate memory for the isaac state." ); + return -1; + } + } + + /* Take the minimum of the isaac seed size and available entropy. */ + if( sizeof( isaac_state->randrsl ) < seed->length ) + { + count = sizeof( isaac_state->randrsl ); + } + else + { + memset( isaac_state->randrsl, 0, sizeof( isaac_state->randrsl ) ); + count = seed->length; + } + + if( count == 0 ) + { + /* Start ISACC without a seed. */ + randinit( isaac_state, 0 ); + } + else + { + /* Seed the ISAAC state with entropy. */ + memcpy( isaac_state->randrsl, seed->s, count ); + + /* The second parameter indicates that randrsl is non-empty. */ + randinit( isaac_state, 1 ); + } + + return 0; +} + +int nwipe_isaac_read( NWIPE_PRNG_READ_SIGNATURE ) +{ + randctx* isaac_state = *state; + u8* restrict bufpos = buffer; + size_t words = count / SIZE_OF_ISAAC; // the values of isaac is strictly 4 bytes + + /* Isaac returns 4-bytes per call, so progress by 4 bytes. */ + for( size_t ii = 0; ii < words; ++ii ) + { + /* get the next 32bit random number */ + u32_to_buffer( bufpos, isaac_nextval( isaac_state ), SIZE_OF_ISAAC ); + bufpos += SIZE_OF_ISAAC; + } + + /* If there is some remainder copy only relevant number of bytes to not overflow the buffer. */ + const size_t remain = count % SIZE_OF_ISAAC; // SIZE_OF_ISAAC is strictly 4 bytes + if( remain > 0 ) + { + u32_to_buffer( bufpos, isaac_nextval( isaac_state ), remain ); + } + + return 0; +} + +int nwipe_isaac64_init( NWIPE_PRNG_INIT_SIGNATURE ) +{ + int count; + rand64ctx* isaac_state = *state; + + nwipe_log( NWIPE_LOG_NOTICE, "Initialising ISAAC-64 prng" ); + + if( *state == NULL ) + { + /* This is the first time that we have been called. */ + *state = malloc( sizeof( rand64ctx ) ); + isaac_state = *state; + + /* Check the memory allocation. */ + if( isaac_state == 0 ) + { + nwipe_perror( errno, __FUNCTION__, "malloc" ); + nwipe_log( NWIPE_LOG_FATAL, "Unable to allocate memory for the isaac state." ); + return -1; + } + } + + /* Take the minimum of the isaac seed size and available entropy. */ + if( sizeof( isaac_state->randrsl ) < seed->length ) + { + count = sizeof( isaac_state->randrsl ); + } + else + { + memset( isaac_state->randrsl, 0, sizeof( isaac_state->randrsl ) ); + count = seed->length; + } + + if( count == 0 ) + { + /* Start ISACC without a seed. */ + rand64init( isaac_state, 0 ); + } + else + { + /* Seed the ISAAC state with entropy. */ + memcpy( isaac_state->randrsl, seed->s, count ); + + /* The second parameter indicates that randrsl is non-empty. */ + rand64init( isaac_state, 1 ); + } + + return 0; +} + +int nwipe_isaac64_read( NWIPE_PRNG_READ_SIGNATURE ) +{ + rand64ctx* isaac_state = *state; + u8* restrict bufpos = buffer; + size_t words = count / SIZE_OF_ISAAC64; // the values of ISAAC-64 is strictly 8 bytes + + for( size_t ii = 0; ii < words; ++ii ) + { + u64_to_buffer( bufpos, isaac64_nextval( isaac_state ), SIZE_OF_ISAAC64 ); + bufpos += SIZE_OF_ISAAC64; + } + + /* If there is some remainder copy only relevant number of bytes to not overflow the buffer. */ + const size_t remain = count % SIZE_OF_ISAAC64; // SIZE_OF_ISAAC64 is strictly 8 bytes + if( remain > 0 ) + { + u64_to_buffer( bufpos, isaac64_nextval( isaac_state ), remain ); + } + + return 0; +} |