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make BN_FLG_CONSTTIME semantics more fool-proof

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Bodo Möller
2007-03-28 18:44:01 +00:00
parent 7cdb81582c
commit 2ac061e487
3 changed files with 5 additions and 5 deletions
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6
CHANGES
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@@ -14,9 +14,9 @@
BN_mod_inverse_no_branch() of BN_div() and BN_mod_inverse(), BN_mod_inverse_no_branch() of BN_div() and BN_mod_inverse(),
respectively, which are slower, but avoid the security-relevant respectively, which are slower, but avoid the security-relevant
conditional branches. These are automatically called by BN_div() conditional branches. These are automatically called by BN_div()
and BN_mod_inverse() if the flag BN_FLG_CONSTTIME is set for the and BN_mod_inverse() if the flag BN_FLG_CONSTTIME is set for one
modulus. Also, BN_is_bit_set() has been changed to remove a of the input BIGNUMs. Also, BN_is_bit_set() has been changed to
conditional branch. remove a conditional branch.
BN_FLG_CONSTTIME is the new name for the previous BN_FLG_CONSTTIME is the new name for the previous
BN_FLG_EXP_CONSTTIME flag, since it now affects more than just BN_FLG_EXP_CONSTTIME flag, since it now affects more than just

2
crypto/bn/bn_div.c
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@@ -185,7 +185,7 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
BN_ULONG d0,d1; BN_ULONG d0,d1;
int num_n,div_n; int num_n,div_n;
if (BN_get_flags(num, BN_FLG_CONSTTIME) != 0) if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0))
{ {
return BN_div_no_branch(dv, rm, num, divisor, ctx); return BN_div_no_branch(dv, rm, num, divisor, ctx);
} }

2
crypto/bn/bn_gcd.c
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@@ -210,7 +210,7 @@ BIGNUM *BN_mod_inverse(BIGNUM *in,
BIGNUM *ret=NULL; BIGNUM *ret=NULL;
int sign; int sign;
if (BN_get_flags(n, BN_FLG_CONSTTIME) != 0) if ((BN_get_flags(a, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(n, BN_FLG_CONSTTIME) != 0))
{ {
return BN_mod_inverse_no_branch(in, a, n, ctx); return BN_mod_inverse_no_branch(in, a, n, ctx);
} }