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Merge pull request #3734 from SparkiDev/sp_int_8_bit

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SP int: fixes for 8-bit digits
This commit is contained in:
toddouska
2021-02-09 15:59:26 -08:00
committed by GitHub
parent 2f47934184 7986b37aa5
commit ae3706d5e5
3 changed files with 70 additions and 1 deletions
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48
wolfcrypt/src/sp_int.c
View File

@ -4817,11 +4817,17 @@ int sp_mod(sp_int* a, sp_int* m, sp_int* r)
sp_int_word w;
sp_int_word l;
sp_int_word h;
#ifdef SP_WORD_OVERFLOW
sp_int_word o;
#endif
w = (sp_int_word)a->dp[0] * b->dp[0];
t->dp[0] = (sp_int_digit)w;
l = (sp_int_digit)(w >> SP_WORD_SIZE);
h = 0;
#ifdef SP_WORD_OVERFLOW
o = 0;
#endif
for (k = 1; k <= (a->used - 1) + (b->used - 1); k++) {
i = k - (b->used - 1);
i &= ~(i >> (sizeof(i) * 8 - 1));
@ -4830,11 +4836,21 @@ int sp_mod(sp_int* a, sp_int* m, sp_int* r)
w = (sp_int_word)a->dp[i] * b->dp[j];
l += (sp_int_digit)w;
h += (sp_int_digit)(w >> SP_WORD_SIZE);
#ifdef SP_WORD_OVERFLOW
h += (sp_int_digit)(l >> SP_WORD_SIZE);
l &= SP_MASK;
o += (sp_int_digit)(h >> SP_WORD_SIZE);
h &= SP_MASK;
#endif
}
t->dp[k] = (sp_int_digit)l;
l >>= SP_WORD_SIZE;
l += (sp_int_digit)h;
h >>= SP_WORD_SIZE;
#ifdef SP_WORD_OVERFLOW
h += o & SP_MASK;
o >>= SP_WORD_SIZE;
#endif
}
t->dp[k] = (sp_int_digit)l;
t->dp[k+1] = (sp_int_digit)h;
@ -9590,12 +9606,20 @@ int sp_mul_2d(sp_int* a, int e, sp_int* r)
#endif
if (err == MP_OKAY) {
sp_int_word w, l, h;
sp_int_word w;
sp_int_word l;
sp_int_word h;
#ifdef SP_WORD_OVERFLOW
sp_int_word o;
#endif
w = (sp_int_word)a->dp[0] * a->dp[0];
t->dp[0] = (sp_int_digit)w;
l = (sp_int_digit)(w >> SP_WORD_SIZE);
h = 0;
#ifdef SP_WORD_OVERFLOW
o = 0;
#endif
for (k = 1; k <= (a->used - 1) * 2; k++) {
i = k / 2;
j = k - i;
@ -9603,18 +9627,40 @@ int sp_mul_2d(sp_int* a, int e, sp_int* r)
w = (sp_int_word)a->dp[i] * a->dp[j];
l += (sp_int_digit)w;
h += (sp_int_digit)(w >> SP_WORD_SIZE);
#ifdef SP_WORD_OVERFLOW
h += (sp_int_digit)(l >> SP_WORD_SIZE);
l &= SP_MASK;
o += (sp_int_digit)(h >> SP_WORD_SIZE);
h &= SP_MASK;
#endif
}
for (++i, --j; (i < a->used) && (j >= 0); i++, j--) {
w = (sp_int_word)a->dp[i] * a->dp[j];
l += (sp_int_digit)w;
h += (sp_int_digit)(w >> SP_WORD_SIZE);
#ifdef SP_WORD_OVERFLOW
h += (sp_int_digit)(l >> SP_WORD_SIZE);
l &= SP_MASK;
o += (sp_int_digit)(h >> SP_WORD_SIZE);
h &= SP_MASK;
#endif
l += (sp_int_digit)w;
h += (sp_int_digit)(w >> SP_WORD_SIZE);
#ifdef SP_WORD_OVERFLOW
h += (sp_int_digit)(l >> SP_WORD_SIZE);
l &= SP_MASK;
o += (sp_int_digit)(h >> SP_WORD_SIZE);
h &= SP_MASK;
#endif
}
t->dp[k] = (sp_int_digit)l;
l >>= SP_WORD_SIZE;
l += (sp_int_digit)h;
h >>= SP_WORD_SIZE;
#ifdef SP_WORD_OVERFLOW
h += o & SP_MASK;
o >>= SP_WORD_SIZE;
#endif
}
t->dp[k] = (sp_int_digit)l;
t->dp[k+1] = (sp_int_digit)h;

4
wolfcrypt/src/wolfmath.c
View File

@ -100,7 +100,11 @@ int mp_cond_copy(mp_int* a, int copy, mp_int* b)
{
int err = MP_OKAY;
int i;
#if defined(SP_WORD_SIZE) && SP_WORD_SIZE == 8
unsigned int mask = (unsigned int)0 - copy;
#else
mp_digit mask = (mp_digit)0 - copy;
#endif
if (a == NULL || b == NULL)
err = BAD_FUNC_ARG;

19
wolfssl/wolfcrypt/sp_int.h
View File

@ -376,6 +376,25 @@ typedef struct sp_ecc_ctx {
#define SP_INT_MAX_BITS (SP_INT_DIGITS * SP_WORD_SIZE)
#endif
#if SP_WORD_SIZE < 32
/* Maximum number of digits in a number to mul or sqr. */
#define SP_MUL_SQR_DIGITS (SP_INT_MAX_BITS / 2 / SP_WORD_SIZE)
/* Maximum value of partial in mul/sqr. */
#define SP_MUL_SQR_MAX_PARTIAL \
(SP_MUL_SQR_DIGITS * ((1 << SP_WORD_SIZE) - 1))
/* Maximim value in an sp_int_word. */
#define SP_INT_WORD_MAX ((1 << (SP_WORD_SIZE * 2)) - 1)
#if SP_MUL_SQR_MAX_PARTIAL > SP_INT_WORD_MAX
/* The sum of the partials in the multiplicaiton/square can exceed the
* size of a word. This will overflow the word and loose data.
* Use an implementation that handles carry after every add and uses an
* extra temporary word for overflowing high word.
*/
#define SP_WORD_OVERFLOW
#endif
#endif
/* For debugging only - format string for different digit sizes. */
#if SP_WORD_SIZE == 64