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Fix encode and decoding of EC signature

pull/1834/head
Sean Parkinson 2018-09-19 13:47:58 +10:00
parent 77a81057be
commit f7f158cbd9
1 changed files with 41 additions and 30 deletions
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71
wolfcrypt/src/wc_pkcs11.c
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@ -1361,41 +1361,48 @@ static int Pkcs11ECDH(Pkcs11Session* session, wc_CryptoInfo* info)
*/ */
static word32 Pkcs11ECDSASig_Encode(byte* sig, word32 sz) static word32 Pkcs11ECDSASig_Encode(byte* sig, word32 sz)
{ {
word32 rHigh, sHigh; word32 rHigh, sHigh, seqLen;
word32 rStart = 0, sStart = 0; word32 rStart = 0, sStart = 0;
word32 sigSz; word32 sigSz;
word32 i; word32 i;
/* Find first byte of data in r and s. */ /* Find first byte of data in r and s. */
while (sig[rStart] == 0x00) while (sig[rStart] == 0x00 && rStart < sz - 1)
rStart++; rStart++;
while (sig[sz + sStart] == 0x00) while (sig[sz + sStart] == 0x00 && sStart < sz - 1)
sStart++; sStart++;
/* Check if 0 needs to be prepended to make integer a poisitive number. */ /* Check if 0 needs to be prepended to make integer a positive number. */
rHigh = (sig[rStart] & 0x80) >> 7; rHigh = sig[rStart] >> 7;
sHigh = (sig[sz + sStart] & 0x80) >> 7; sHigh = sig[sz + sStart] >> 7;
/* Calculate the complete ASN.1 DER encoded size. */ /* Calculate the complete ASN.1 DER encoded size. */
sigSz = 2 + 2 + rHigh + (sz - rStart) + 2 + sHigh + (sz - sStart); sigSz = 2 + rHigh + (sz - rStart) + 2 + sHigh + (sz - sStart);
if (sigSz >= 128)
seqLen = 3;
else
seqLen = 2;
/* Move s and r into their final places. */ /* Move s and then r into their final places. */
XMEMMOVE(sig + 2 + 2 + rHigh + (sz - rStart) + 2 + sHigh, sig + sz, XMEMMOVE(sig + seqLen + 2 + rHigh + (sz - rStart) + 2 + sHigh,
sz - sStart); sig + sz + sStart, sz - sStart);
XMEMMOVE(sig + 2 + 2 + rHigh, sig, sz - rStart); XMEMMOVE(sig + seqLen + 2 + rHigh, sig + rStart, sz - rStart);
/* Put the ASN.1 DER encoding around data. */ /* Put the ASN.1 DER encoding around data. */
sig[0] = ASN_CONSTRUCTED | ASN_SEQUENCE; i = 0;
sig[1] = sigSz - 2; sig[i++] = ASN_CONSTRUCTED | ASN_SEQUENCE;
sig[2] = ASN_INTEGER; if (seqLen == 3)
sig[3] = rHigh + (sz - rStart); sig[i++] = 0x81;
sig[i++] = sigSz;
sig[i++] = ASN_INTEGER;
sig[i++] = rHigh + (sz - rStart);
if (rHigh) if (rHigh)
sig[4] = 0x00; sig[i++] = 0x00;
i = 2 + 2 + rHigh + (sz - rStart); i += sz - rStart;
sig[i + 0] = ASN_INTEGER; sig[i++] = ASN_INTEGER;
sig[i + 1] = sHigh + (sz - sStart); sig[i++] = sHigh + (sz - sStart);
if (sHigh) if (sHigh)
sig[i + 2] = 0x00; sig[i] = 0x00;
return sigSz; return seqLen + sigSz;
} }
/** /**
@ -1414,18 +1421,26 @@ static int Pkcs11ECDSASig_Decode(const byte* in, word32 inSz, byte* sig,
{ {
int ret = 0; int ret = 0;
word32 i = 0; word32 i = 0;
int len; int len, seqLen = 2;
/* Make sure zeros in place when decoding short integers. */ /* Make sure zeros in place when decoding short integers. */
XMEMSET(sig, 0, sz * 2); XMEMSET(sig, 0, sz * 2);
/* Check min data for: SEQ + INT. */ /* Check min data for: SEQ + INT. */
if (inSz < 4) if (inSz < 5)
ret = ASN_PARSE_E; ret = ASN_PARSE_E;
/* Check SEQ */ /* Check SEQ */
if (ret == 0 && in[i++] != (ASN_CONSTRUCTED | ASN_SEQUENCE)) if (ret == 0 && in[i++] != (ASN_CONSTRUCTED | ASN_SEQUENCE))
ret = ASN_PARSE_E; ret = ASN_PARSE_E;
if (ret == 0 && in[i++] != inSz - 2) if (ret == 0 && in[i] >= 0x80) {
if (in[i] != 0x81)
ret = ASN_PARSE_E;
else {
i++;
seqLen++;
}
}
if (ret == 0 && in[i++] != inSz - seqLen)
ret = ASN_PARSE_E; ret = ASN_PARSE_E;
/* Check INT */ /* Check INT */
@ -1433,7 +1448,7 @@ static int Pkcs11ECDSASig_Decode(const byte* in, word32 inSz, byte* sig,
ret = ASN_PARSE_E; ret = ASN_PARSE_E;
if (ret == 0 && (len = in[i++]) > sz + 1) if (ret == 0 && (len = in[i++]) > sz + 1)
ret = ASN_PARSE_E; ret = ASN_PARSE_E;
/* Check space for INT */ /* Check there is space for INT data */
if (ret == 0 && i + len > inSz) if (ret == 0 && i + len > inSz)
ret = ASN_PARSE_E; ret = ASN_PARSE_E;
if (ret == 0) { if (ret == 0) {
@ -1442,8 +1457,6 @@ static int Pkcs11ECDSASig_Decode(const byte* in, word32 inSz, byte* sig,
i++; i++;
len--; len--;
} }
}
if (ret == 0) {
/* Copy r into sig. */ /* Copy r into sig. */
XMEMCPY(sig + sz - len, in + i, len); XMEMCPY(sig + sz - len, in + i, len);
i += len; i += len;
@ -1457,7 +1470,7 @@ static int Pkcs11ECDSASig_Decode(const byte* in, word32 inSz, byte* sig,
ret = ASN_PARSE_E; ret = ASN_PARSE_E;
if (ret == 0 && (len = in[i++]) > sz + 1) if (ret == 0 && (len = in[i++]) > sz + 1)
ret = ASN_PARSE_E; ret = ASN_PARSE_E;
/* Check space for INT */ /* Check there is space for INT data */
if (ret == 0 && i + len > inSz) if (ret == 0 && i + len > inSz)
ret = ASN_PARSE_E; ret = ASN_PARSE_E;
if (ret == 0) { if (ret == 0) {
@ -1466,8 +1479,6 @@ static int Pkcs11ECDSASig_Decode(const byte* in, word32 inSz, byte* sig,
i++; i++;
len--; len--;
} }
}
if (ret == 0) {
/* Copy s into sig. */ /* Copy s into sig. */
XMEMCPY(sig + sz + sz - len, in + i, len); XMEMCPY(sig + sz + sz - len, in + i, len);
} }