commit a49149fc13e8b81e30df17579f19408ae8f4200f Author: Nick Mathewson nickm@torproject.org Date: Wed Feb 6 12:40:01 2019 -0500
Extract numeric CSPRNG functions into a new module.
Some of the code for getting a random value within a range wants to be shared between crypto_rand() and the new crypto_fast_rng() code. --- src/lib/crypt_ops/crypto_rand.c | 108 ----------------------------- src/lib/crypt_ops/crypto_rand_numeric.c | 117 ++++++++++++++++++++++++++++++++ src/lib/crypt_ops/include.am | 1 + 3 files changed, 118 insertions(+), 108 deletions(-)
diff --git a/src/lib/crypt_ops/crypto_rand.c b/src/lib/crypt_ops/crypto_rand.c index 5a739a8f1..14c2434a8 100644 --- a/src/lib/crypt_ops/crypto_rand.c +++ b/src/lib/crypt_ops/crypto_rand.c @@ -539,114 +539,6 @@ crypto_rand_u32(void) }
/** - * Return a pseudorandom integer, chosen uniformly from the values - * between 0 and <b>max</b>-1 inclusive. <b>max</b> must be between 1 and - * INT_MAX+1, inclusive. - */ -int -crypto_rand_int(unsigned int max) -{ - unsigned int val; - unsigned int cutoff; - tor_assert(max <= ((unsigned int)INT_MAX)+1); - tor_assert(max > 0); /* don't div by 0 */ - - /* We ignore any values that are >= 'cutoff,' to avoid biasing the - * distribution with clipping at the upper end of unsigned int's - * range. - */ - cutoff = UINT_MAX - (UINT_MAX%max); - while (1) { - crypto_rand((char*)&val, sizeof(val)); - if (val < cutoff) - return val % max; - } -} - -/** - * Return a pseudorandom integer, chosen uniformly from the values i such - * that min <= i < max. - * - * <b>min</b> MUST be in range [0, <b>max</b>). - * <b>max</b> MUST be in range (min, INT_MAX]. - **/ -int -crypto_rand_int_range(unsigned int min, unsigned int max) -{ - tor_assert(min < max); - tor_assert(max <= INT_MAX); - - /* The overflow is avoided here because crypto_rand_int() returns a value - * between 0 and (max - min) inclusive. */ - return min + crypto_rand_int(max - min); -} - -/** - * As crypto_rand_int_range, but supports uint64_t. - **/ -uint64_t -crypto_rand_uint64_range(uint64_t min, uint64_t max) -{ - tor_assert(min < max); - return min + crypto_rand_uint64(max - min); -} - -/** - * As crypto_rand_int_range, but supports time_t. - **/ -time_t -crypto_rand_time_range(time_t min, time_t max) -{ - tor_assert(min < max); - return min + (time_t)crypto_rand_uint64(max - min); -} - -/** - * Return a pseudorandom 64-bit integer, chosen uniformly from the values - * between 0 and <b>max</b>-1 inclusive. - **/ -uint64_t -crypto_rand_uint64(uint64_t max) -{ - uint64_t val; - uint64_t cutoff; - tor_assert(max < UINT64_MAX); - tor_assert(max > 0); /* don't div by 0 */ - - /* We ignore any values that are >= 'cutoff,' to avoid biasing the - * distribution with clipping at the upper end of unsigned int's - * range. - */ - cutoff = UINT64_MAX - (UINT64_MAX%max); - while (1) { - crypto_rand((char*)&val, sizeof(val)); - if (val < cutoff) - return val % max; - } -} - -/** - * Return a pseudorandom double d, chosen uniformly from the range - * 0.0 <= d < 1.0. - **/ -double -crypto_rand_double(void) -{ - /* We just use an unsigned int here; we don't really care about getting - * more than 32 bits of resolution */ - unsigned int u; - crypto_rand((char*)&u, sizeof(u)); -#if SIZEOF_INT == 4 -#define UINT_MAX_AS_DOUBLE 4294967296.0 -#elif SIZEOF_INT == 8 -#define UINT_MAX_AS_DOUBLE 1.8446744073709552e+19 -#else -#error SIZEOF_INT is neither 4 nor 8 -#endif /* SIZEOF_INT == 4 || ... */ - return ((double)u) / UINT_MAX_AS_DOUBLE; -} - -/** * Generate and return a new random hostname starting with <b>prefix</b>, * ending with <b>suffix</b>, and containing no fewer than * <b>min_rand_len</b> and no more than <b>max_rand_len</b> random base32 diff --git a/src/lib/crypt_ops/crypto_rand_numeric.c b/src/lib/crypt_ops/crypto_rand_numeric.c new file mode 100644 index 000000000..97fe3bd18 --- /dev/null +++ b/src/lib/crypt_ops/crypto_rand_numeric.c @@ -0,0 +1,117 @@ +/** + * \file crypto_rand_numeric.c + * + * \brief Functions for retrieving uniformly distributed numbers + * from our PRNGs. + **/ + +#include "lib/crypt_ops/crypto_rand.h" +#include "lib/log/util_bug.h" + +/** + * Return a pseudorandom integer, chosen uniformly from the values + * between 0 and <b>max</b>-1 inclusive. <b>max</b> must be between 1 and + * INT_MAX+1, inclusive. + */ +int +crypto_rand_int(unsigned int max) +{ + unsigned int val; + unsigned int cutoff; + tor_assert(max <= ((unsigned int)INT_MAX)+1); + tor_assert(max > 0); /* don't div by 0 */ + + /* We ignore any values that are >= 'cutoff,' to avoid biasing the + * distribution with clipping at the upper end of unsigned int's + * range. + */ + cutoff = UINT_MAX - (UINT_MAX%max); + while (1) { + crypto_rand((char*)&val, sizeof(val)); + if (val < cutoff) + return val % max; + } +} + +/** + * Return a pseudorandom integer, chosen uniformly from the values i such + * that min <= i < max. + * + * <b>min</b> MUST be in range [0, <b>max</b>). + * <b>max</b> MUST be in range (min, INT_MAX]. + **/ +int +crypto_rand_int_range(unsigned int min, unsigned int max) +{ + tor_assert(min < max); + tor_assert(max <= INT_MAX); + + /* The overflow is avoided here because crypto_rand_int() returns a value + * between 0 and (max - min) inclusive. */ + return min + crypto_rand_int(max - min); +} + +/** + * As crypto_rand_int_range, but supports uint64_t. + **/ +uint64_t +crypto_rand_uint64_range(uint64_t min, uint64_t max) +{ + tor_assert(min < max); + return min + crypto_rand_uint64(max - min); +} + +/** + * As crypto_rand_int_range, but supports time_t. + **/ +time_t +crypto_rand_time_range(time_t min, time_t max) +{ + tor_assert(min < max); + return min + (time_t)crypto_rand_uint64(max - min); +} + +/** + * Return a pseudorandom 64-bit integer, chosen uniformly from the values + * between 0 and <b>max</b>-1 inclusive. + **/ +uint64_t +crypto_rand_uint64(uint64_t max) +{ + uint64_t val; + uint64_t cutoff; + tor_assert(max < UINT64_MAX); + tor_assert(max > 0); /* don't div by 0 */ + + /* We ignore any values that are >= 'cutoff,' to avoid biasing the + * distribution with clipping at the upper end of unsigned int's + * range. + */ + cutoff = UINT64_MAX - (UINT64_MAX%max); + while (1) { + crypto_rand((char*)&val, sizeof(val)); + if (val < cutoff) + return val % max; + } +} + +/** + * Return a pseudorandom double d, chosen uniformly from the range + * 0.0 <= d < 1.0. + **/ +double +crypto_rand_double(void) +{ + /* We just use an unsigned int here; we don't really care about getting + * more than 32 bits of resolution */ + unsigned int u; + crypto_rand((char*)&u, sizeof(u)); +#if SIZEOF_INT == 4 +#define UINT_MAX_AS_DOUBLE 4294967296.0 +#elif SIZEOF_INT == 8 +#define UINT_MAX_AS_DOUBLE 1.8446744073709552e+19 +#else +#error SIZEOF_INT is neither 4 nor 8 +#endif /* SIZEOF_INT == 4 || ... */ + return ((double)u) / UINT_MAX_AS_DOUBLE; +} diff --git a/src/lib/crypt_ops/include.am b/src/lib/crypt_ops/include.am index d0ccc13bf..19cfee135 100644 --- a/src/lib/crypt_ops/include.am +++ b/src/lib/crypt_ops/include.am @@ -17,6 +17,7 @@ src_lib_libtor_crypt_ops_a_SOURCES = \ src/lib/crypt_ops/crypto_ope.c \ src/lib/crypt_ops/crypto_pwbox.c \ src/lib/crypt_ops/crypto_rand.c \ + src/lib/crypt_ops/crypto_rand_numeric.c \ src/lib/crypt_ops/crypto_rsa.c \ src/lib/crypt_ops/crypto_s2k.c \ src/lib/crypt_ops/crypto_util.c \