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Check HKDF-Expand length of output <= 255*HashLen #2956

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Merged
JacobBarthelmeh merged 2 commits into from
May 8, 2020
Merged

Check HKDF-Expand length of output <= 255*HashLen #2956

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Check length of output <= 255*HashLen
tmael May 6, 2020
b39e384
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tmael May 7, 2020
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7 changes: 7 additions & 0 deletions wolfcrypt/src/hmac.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1216,10 +1216,17 @@ int wolfSSL_GetHmacMaxSize(void)
word32 hashSz = wc_HmacSizeByType(type);
byte n = 0x1;

/* RFC 5869 states that the length of output keying material in
octets must be L <= 255*HashLen or N = ceil(L/HashLen) */

if (out == NULL || ((outSz/hashSz) + ((outSz % hashSz) != 0)) > 255)
return BAD_FUNC_ARG;

ret = wc_HmacInit(&myHmac, NULL, INVALID_DEVID);
if (ret != 0)
return ret;


while (outIdx < outSz) {
int tmpSz = (n == 1) ? 0 : hashSz;
word32 left = outSz - outIdx;
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