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Merge pull request #2755 from SparkiDev/rsa_enc_3072

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Fix masking of 16 bits
This commit is contained in:
David Garske
2020-01-22 13:40:21 -08:00
committed by GitHub
parent 7707234901 55d485cc45
commit e3efdc4b5d
2 changed files with 13 additions and 1 deletions
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12
wolfcrypt/src/misc.c
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@ -356,9 +356,19 @@ WC_STATIC WC_INLINE byte ctMaskEq(int a, int b)
return (~ctMaskGT(a, b)) & (~ctMaskLT(a, b)); return (~ctMaskGT(a, b)) & (~ctMaskLT(a, b));
} }
WC_STATIC WC_INLINE word16 ctMask16GT(int a, int b)
{
return (((word32)a - b - 1) >> 31) - 1;
}
WC_STATIC WC_INLINE word16 ctMask16LT(int a, int b)
{
return (((word32)a - b - 1) >> 31) - 1;
}
WC_STATIC WC_INLINE word16 ctMask16Eq(int a, int b) WC_STATIC WC_INLINE word16 ctMask16Eq(int a, int b)
{ {
return (~ctMaskGT(a, b)) & (~ctMaskLT(a, b)); return (~ctMask16GT(a, b)) & (~ctMask16LT(a, b));
} }
/* Constant time - mask set when a != b. */ /* Constant time - mask set when a != b. */

2
wolfssl/wolfcrypt/misc.h
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@ -98,6 +98,8 @@ WOLFSSL_LOCAL int ctMaskIntGTE(int a, int b);
WOLFSSL_LOCAL byte ctMaskLT(int a, int b); WOLFSSL_LOCAL byte ctMaskLT(int a, int b);
WOLFSSL_LOCAL byte ctMaskLTE(int a, int b); WOLFSSL_LOCAL byte ctMaskLTE(int a, int b);
WOLFSSL_LOCAL byte ctMaskEq(int a, int b); WOLFSSL_LOCAL byte ctMaskEq(int a, int b);
WOLFSSL_LOCAL word16 ctMask16GT(int a, int b);
WOLFSSL_LOCAL word16 ctMask16LT(int a, int b);
WOLFSSL_LOCAL word16 ctMask16Eq(int a, int b); WOLFSSL_LOCAL word16 ctMask16Eq(int a, int b);
WOLFSSL_LOCAL byte ctMaskNotEq(int a, int b); WOLFSSL_LOCAL byte ctMaskNotEq(int a, int b);
WOLFSSL_LOCAL byte ctMaskSel(byte m, byte a, byte b); WOLFSSL_LOCAL byte ctMaskSel(byte m, byte a, byte b);