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Don't use memmove, but use memcpy with dummy memory area.

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Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka
2020-09-09 08:55:09 +09:00
parent dd47cf4312
commit 2142d0aa35
3 changed files with 28 additions and 8 deletions
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7
ChangeLog
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@@ -1,3 +1,10 @@
2020-09-09 NIIBE Yutaka <gniibe@fsij.org>
* src/modp256k1.c (modp256k1_add, modp256k1_sub): Use memcpy with
dummy memory area.
* src/modp256r1.c (modp256r1_add, modp256r1_sub)
(modp256r1_reduce): Likewise.
2020-09-08 NIIBE Yutaka <gniibe@fsij.org>
* src/modp256k1.c (modp256k1_add, modp256k1_reduce): Avoid

8
src/modp256k1.c
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@@ -71,10 +71,12 @@ modp256k1_add (bn256 *X, const bn256 *A, const bn256 *B)
{
uint32_t cond;
bn256 tmp[1];
bn256 dummy[1];
cond = (bn256_add (X, A, B) == 0);
cond &= bn256_sub (tmp, X, P256K1);
memmove (cond?tmp:X, tmp, sizeof (bn256));
memcpy (cond?dummy:X, tmp, sizeof (bn256));
asm ("" : "=m" (dummy) : "m" (dummy) : "memory");
}
/**
@@ -85,10 +87,12 @@ modp256k1_sub (bn256 *X, const bn256 *A, const bn256 *B)
{
uint32_t borrow;
bn256 tmp[1];
bn256 dummy[1];
borrow = bn256_sub (X, A, B);
bn256_add (tmp, X, P256K1);
memmove (borrow?X:tmp, tmp, sizeof (bn256));
memcpy (borrow?X:dummy, tmp, sizeof (bn256));
asm ("" : "=m" (dummy) : "m" (dummy) : "memory");
}
/**

21
src/modp256r1.c
View File

@@ -66,10 +66,12 @@ modp256r1_add (bn256 *X, const bn256 *A, const bn256 *B)
{
uint32_t cond;
bn256 tmp[1];
bn256 dummy[1];
cond = (bn256_add (X, A, B) == 0);
cond &= bn256_sub (tmp, X, P256R1);
memmove (cond?tmp:X, tmp, sizeof (bn256));
memcpy (cond?dummy:X, tmp, sizeof (bn256));
asm ("" : "=m" (dummy) : "m" (dummy) : "memory");
}
/**
@@ -80,10 +82,12 @@ modp256r1_sub (bn256 *X, const bn256 *A, const bn256 *B)
{
uint32_t borrow;
bn256 tmp[1];
bn256 dummy[1];
borrow = bn256_sub (X, A, B);
bn256_add (tmp, X, P256R1);
memmove (borrow?X:tmp, tmp, sizeof (bn256));
memcpy (borrow?X:dummy, tmp, sizeof (bn256));
asm ("" : "=m" (dummy) : "m" (dummy) : "memory");
}
/**
@@ -93,6 +97,7 @@ void
modp256r1_reduce (bn256 *X, const bn512 *A)
{
bn256 tmp[1], tmp0[1];
bn256 dummy[1];
uint32_t borrow;
#define S1 X
@@ -114,7 +119,8 @@ modp256r1_reduce (bn256 *X, const bn512 *A)
S1->word[1] = A->word[1];
S1->word[0] = A->word[0];
borrow = bn256_sub (tmp0, S1, P256R1);
memmove (borrow?tmp0:S1, tmp0, sizeof (bn256));
memcpy (borrow?dummy:S1, tmp0, sizeof (bn256));
asm ("" : "=m" (dummy) : "m" (dummy) : "memory");
/* X = S1 */
S2->word[7] = A->word[15];
@@ -155,7 +161,8 @@ modp256r1_reduce (bn256 *X, const bn512 *A)
S5->word[1] = A->word[10];
S5->word[0] = A->word[9];
borrow = bn256_sub (tmp0, S5, P256R1);
memmove (borrow?tmp0:S5, tmp0, sizeof (bn256));
memcpy (borrow?dummy:S5, tmp0, sizeof (bn256));
asm ("" : "=m" (dummy) : "m" (dummy) : "memory");
/* X += S5 */
modp256r1_add (X, X, S5);
@@ -166,7 +173,8 @@ modp256r1_reduce (bn256 *X, const bn512 *A)
S6->word[1] = A->word[12];
S6->word[0] = A->word[11];
borrow = bn256_sub (tmp0, S6, P256R1);
memmove (borrow?tmp0:S6, tmp0, sizeof (bn256));
memcpy (borrow?dummy:S6, tmp0, sizeof (bn256));
asm ("" : "=m" (dummy) : "m" (dummy) : "memory");
/* X -= S6 */
modp256r1_sub (X, X, S6);
@@ -178,7 +186,8 @@ modp256r1_reduce (bn256 *X, const bn512 *A)
S7->word[1] = A->word[13];
S7->word[0] = A->word[12];
borrow = bn256_sub (tmp0, S7, P256R1);
memmove (borrow?tmp0:S7, tmp0, sizeof (bn256));
memcpy (borrow?dummy:S7, tmp0, sizeof (bn256));
asm ("" : "=m" (dummy) : "m" (dummy) : "memory");
/* X -= S7 */
modp256r1_sub (X, X, S7);