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fix dsa pre padding

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toddouska 2016-09-21 18:51:11 -07:00
parent 2368d49678
commit 9e4e08d7a7
1 changed files with 8 additions and 8 deletions
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16
wolfcrypt/src/dsa.c
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@ -356,6 +356,7 @@ int wc_DsaSign(const byte* digest, byte* out, DsaKey* key, WC_RNG* rng)
mp_int k, kInv, r, s, H; mp_int k, kInv, r, s, H;
int ret, sz; int ret, sz;
byte buffer[DSA_HALF_SIZE]; byte buffer[DSA_HALF_SIZE];
byte* tmp = out; /* initial output pointer */
sz = min((int)sizeof(buffer), mp_unsigned_bin_size(&key->q)); sz = min((int)sizeof(buffer), mp_unsigned_bin_size(&key->q));
@ -405,19 +406,18 @@ int wc_DsaSign(const byte* digest, byte* out, DsaKey* key, WC_RNG* rng)
int rSz = mp_unsigned_bin_size(&r); int rSz = mp_unsigned_bin_size(&r);
int sSz = mp_unsigned_bin_size(&s); int sSz = mp_unsigned_bin_size(&s);
if (rSz == DSA_HALF_SIZE - 1) { while (rSz++ < DSA_HALF_SIZE) {
out[0] = 0; *out++ = 0x00; /* pad front with zeros */
out++;
} }
if (mp_to_unsigned_bin(&r, out) != MP_OKAY) if (mp_to_unsigned_bin(&r, out) != MP_OKAY)
ret = MP_TO_E; ret = MP_TO_E;
else { else {
if (sSz == DSA_HALF_SIZE - 1) { out = tmp + DSA_HALF_SIZE; /* advance to s in output */
out[rSz] = 0; while (sSz++ < DSA_HALF_SIZE) {
out++; *out++ = 0x00; /* pad front with zeros */
} }
ret = mp_to_unsigned_bin(&s, out + rSz); ret = mp_to_unsigned_bin(&s, out);
} }
} }