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Improvement to ECC wc_ecc_sig_to_rs to reduce memory use (avoid the mp_int).

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This commit is contained in:
David Garske
2020-10-22 13:34:19 -07:00
parent cb8e625e32
commit 0065756efc
3 changed files with 48 additions and 61 deletions
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46
wolfcrypt/src/asn.c
View File

@ -15428,7 +15428,51 @@ int StoreECC_DSA_Sig(byte* out, word32* outLen, mp_int* r, mp_int* s)
}
/* Der Decode ECC-DSA Signature, r & s stored as big ints */
/* Der Decode ECC-DSA Signature with R/S as unsigned bin */
int DecodeECC_DSA_Sig_Bin(const byte* sig, word32 sigLen, byte* r, word32* rLen,
byte* s, word32* sLen)
{
int ret;
word32 idx = 0;
int len = 0;
if (GetSequence(sig, &idx, &len, sigLen) < 0) {
return ASN_ECC_KEY_E;
}
#ifndef NO_STRICT_ECDSA_LEN
/* enable strict length checking for signature */
if (sigLen != idx + (word32)len) {
return ASN_ECC_KEY_E;
}
#else
/* allow extra signature bytes at end */
if ((word32)len > (sigLen - idx)) {
return ASN_ECC_KEY_E;
}
#endif
ret = GetASNInt(sig, &idx, &len, sigLen);
if (ret != 0)
return ret;
if (rLen)
*rLen = len;
if (r)
XMEMCPY(r, (byte*)sig + idx, len);
idx += len;
ret = GetASNInt(sig, &idx, &len, sigLen);
if (ret != 0)
return ret;
if (sLen)
*sLen = len;
if (s)
XMEMCPY(s, (byte*)sig + idx, len);
return ret;
}
int DecodeECC_DSA_Sig(const byte* sig, word32 sigLen, mp_int* r, mp_int* s)
{
word32 idx = 0;

61
wolfcrypt/src/ecc.c
View File

@ -8040,69 +8040,10 @@ int wc_ecc_rs_raw_to_sig(const byte* r, word32 rSz, const byte* s, word32 sSz,
int wc_ecc_sig_to_rs(const byte* sig, word32 sigLen, byte* r, word32* rLen,
byte* s, word32* sLen)
{
int err;
int tmp_valid = 0;
word32 x = 0;
#ifdef WOLFSSL_SMALL_STACK
mp_int* rtmp = NULL;
mp_int* stmp = NULL;
#else
mp_int rtmp[1];
mp_int stmp[1];
#endif
if (sig == NULL || r == NULL || rLen == NULL || s == NULL || sLen == NULL)
return ECC_BAD_ARG_E;
#ifdef WOLFSSL_SMALL_STACK
rtmp = (mp_int*)XMALLOC(sizeof(mp_int), NULL, DYNAMIC_TYPE_ECC);
if (rtmp == NULL)
return MEMORY_E;
stmp = (mp_int*)XMALLOC(sizeof(mp_int), NULL, DYNAMIC_TYPE_ECC);
if (stmp == NULL) {
XFREE(rtmp, NULL, DYNAMIC_TYPE_ECC);
return MEMORY_E;
}
#endif
err = DecodeECC_DSA_Sig(sig, sigLen, rtmp, stmp);
/* rtmp and stmp are initialized */
if (err == MP_OKAY) {
tmp_valid = 1;
/* extract r */
x = mp_unsigned_bin_size(rtmp);
if (*rLen < x)
err = BUFFER_E;
}
if (err == MP_OKAY) {
*rLen = x;
err = mp_to_unsigned_bin(rtmp, r);
}
/* extract s */
if (err == MP_OKAY) {
x = mp_unsigned_bin_size(stmp);
if (*sLen < x)
err = BUFFER_E;
if (err == MP_OKAY) {
*sLen = x;
err = mp_to_unsigned_bin(stmp, s);
}
}
if (tmp_valid) {
mp_clear(rtmp);
mp_clear(stmp);
}
#ifdef WOLFSSL_SMALL_STACK
XFREE(stmp, NULL, DYNAMIC_TYPE_ECC);
XFREE(rtmp, NULL, DYNAMIC_TYPE_ECC);
#endif
return err;
return DecodeECC_DSA_Sig_Bin(sig, sigLen, r, rLen, s, sLen);
}
#endif /* !NO_ASN */

2
wolfssl/wolfcrypt/asn.h
View File

@ -1164,6 +1164,8 @@ WOLFSSL_LOCAL int FlattenAltNames( byte*, word32, const DNS_entry*);
mp_int* s);
WOLFSSL_LOCAL int DecodeECC_DSA_Sig(const byte* sig, word32 sigLen,
mp_int* r, mp_int* s);
WOLFSSL_LOCAL int DecodeECC_DSA_Sig_Bin(const byte* sig, word32 sigLen,
byte* r, word32* rLen, byte* s, word32* sLen);
#endif
#if defined HAVE_ECC && (defined(OPENSSL_EXTRA) || defined(OPENSSL_EXTRA_X509_SMALL))
WOLFSSL_API int EccEnumToNID(int n);