diff options
| -rw-r--r-- | include/internal/constant_time_locl.h | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/include/internal/constant_time_locl.h b/include/internal/constant_time_locl.h index c60e59c6a5..813df63698 100644 --- a/include/internal/constant_time_locl.h +++ b/include/internal/constant_time_locl.h @@ -11,6 +11,7 @@ # define HEADER_CONSTANT_TIME_LOCL_H # include <stdlib.h> +# include <string.h> # include <openssl/e_os2.h> /* For 'ossl_inline' */ #ifdef __cplusplus @@ -33,6 +34,8 @@ extern "C" { /* Returns the given value with the MSB copied to all the other bits. */ static ossl_inline unsigned int constant_time_msb(unsigned int a); +/* Convenience method for uint32_t. */ +static ossl_inline uint32_t constant_time_msb_32(uint32_t a); /* Convenience method for uint64_t. */ static ossl_inline uint64_t constant_time_msb_64(uint64_t a); @@ -56,6 +59,8 @@ static ossl_inline unsigned char constant_time_ge_8(unsigned int a, static ossl_inline unsigned int constant_time_is_zero(unsigned int a); /* Convenience method for getting an 8-bit mask. */ static ossl_inline unsigned char constant_time_is_zero_8(unsigned int a); +/* Convenience method for getting a 32-bit mask. */ +static ossl_inline uint32_t constant_time_is_zero_32(uint32_t a); /* Returns 0xff..f if a == b and 0 otherwise. */ static ossl_inline unsigned int constant_time_eq(unsigned int a, @@ -82,6 +87,11 @@ static ossl_inline unsigned int constant_time_select(unsigned int mask, static ossl_inline unsigned char constant_time_select_8(unsigned char mask, unsigned char a, unsigned char b); + +/* Convenience method for uint32_t. */ +static ossl_inline uint32_t constant_time_select_32(uint32_t mask, uint32_t a, + uint32_t b); + /* Convenience method for uint64_t. */ static ossl_inline uint64_t constant_time_select_64(uint64_t mask, uint64_t a, uint64_t b); @@ -95,6 +105,12 @@ static ossl_inline unsigned int constant_time_msb(unsigned int a) return 0 - (a >> (sizeof(a) * 8 - 1)); } + +static ossl_inline uint32_t constant_time_msb_32(uint32_t a) +{ + return 0 - (a >> 31); +} + static ossl_inline uint64_t constant_time_msb_64(uint64_t a) { return 0 - (a >> 63); @@ -164,6 +180,11 @@ static ossl_inline unsigned char constant_time_is_zero_8(unsigned int a) return (unsigned char)constant_time_is_zero(a); } +static ossl_inline uint32_t constant_time_is_zero_32(uint32_t a) +{ + return constant_time_msb_32(~a & (a - 1)); +} + static ossl_inline unsigned int constant_time_eq(unsigned int a, unsigned int b) { @@ -229,12 +250,84 @@ static ossl_inline int constant_time_select_int_s(size_t mask, int a, int b) (unsigned)(b)); } +static ossl_inline uint32_t constant_time_select_32(uint32_t mask, uint32_t a, + uint32_t b) +{ + return (mask & a) | (~mask & b); +} + static ossl_inline uint64_t constant_time_select_64(uint64_t mask, uint64_t a, uint64_t b) { return (mask & a) | (~mask & b); } +/* + * mask must be 0xFFFFFFFF or 0x00000000. + * + * if (mask) { + * uint32_t tmp = *a; + * + * *a = *b; + * *b = tmp; + * } + */ +static ossl_inline void constant_time_cond_swap_32(uint32_t mask, uint32_t *a, + uint32_t *b) +{ + uint32_t xor = *a ^ *b; + + xor &= mask; + *a ^= xor; + *b ^= xor; +} + +/* + * mask must be 0xFFFFFFFF or 0x00000000. + * + * if (mask) { + * uint64_t tmp = *a; + * + * *a = *b; + * *b = tmp; + * } + */ +static ossl_inline void constant_time_cond_swap_64(uint64_t mask, uint64_t *a, + uint64_t *b) +{ + uint64_t xor = *a ^ *b; + + xor &= mask; + *a ^= xor; + *b ^= xor; +} + +/* + * table is a two dimensional array of bytes. Each row has rowsize elements. + * Copies row number idx into out. rowsize and numrows are not considered + * private. + */ +static ossl_inline void constant_time_lookup(void *out, + const void *table, + size_t rowsize, + size_t numrows, + size_t idx) +{ + size_t i, j; + const unsigned char *tablec = (const unsigned char *)table; + unsigned char *outc = (unsigned char *)out; + unsigned char mask; + + memset(out, 0, rowsize); + + /* Note idx may underflow - but that is well defined */ + for (i = 0; i < numrows; i++, idx--) { + mask = (unsigned char)constant_time_is_zero_s(idx); + for (j = 0; j < rowsize; j++) + *(outc + j) |= constant_time_select_8(mask, *(tablec++), 0); + } +} + #ifdef __cplusplus } #endif |