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asn: refactoring SetEccPublicKey to reduce stack usage: 296 bytes - pointers size moved to the heap.

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--- variable algo moved to the heap (20 bytes saved)
--- variable curve moved to the heap (20 bytes saved)
--- variable pub moved to the heap (256 bytes saved)
This commit is contained in:
Moisés Guimarães
2014-06-27 11:31:25 -03:00
parent 171d7bf920
commit 4aab92c982
1 changed files with 52 additions and 6 deletions
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58
ctaocrypt/src/asn.c
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@ -4759,22 +4759,62 @@ static int SetSerial(const byte* serial, byte* output)
/* Write a public ECC key to output */
static int SetEccPublicKey(byte* output, ecc_key* key)
{
byte algo[MAX_ALGO_SZ];
byte curve[MAX_ALGO_SZ];
byte len[MAX_LENGTH_SZ + 1]; /* trailing 0 */
byte pub[ECC_BUFSIZE];
int algoSz;
int curveSz;
int lenSz;
int idx;
word32 pubSz = sizeof(pub);
word32 pubSz = ECC_BUFSIZE;
#ifdef CYASSL_SMALL_STACK
byte* algo = NULL;
byte* curve = NULL;
byte* pub = NULL;
#else
byte algo[MAX_ALGO_SZ];
byte curve[MAX_ALGO_SZ];
byte pub[ECC_BUFSIZE];
#endif
#ifdef CYASSL_SMALL_STACK
pub = (byte*)XMALLOC(ECC_BUFSIZE, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (pub == NULL)
return MEMORY_E;
#endif
int ret = ecc_export_x963(key, pub, &pubSz);
if (ret != 0) return ret;
if (ret != 0) {
#ifdef CYASSL_SMALL_STACK
XFREE(pub, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ret;
}
#ifdef CYASSL_SMALL_STACK
curve = (byte*)XMALLOC(MAX_ALGO_SZ, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (curve == NULL) {
XFREE(pub, NULL, DYNAMIC_TYPE_TMP_BUFFER);
return MEMORY_E;
}
#endif
/* headers */
curveSz = SetCurve(key, curve);
if (curveSz <= 0) return curveSz;
if (curveSz <= 0) {
#ifdef CYASSL_SMALL_STACK
XFREE(curve, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(pub, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return curveSz;
}
#ifdef CYASSL_SMALL_STACK
algo = (byte*)XMALLOC(MAX_ALGO_SZ, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (algo == NULL) {
XFREE(curve, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(pub, NULL, DYNAMIC_TYPE_TMP_BUFFER);
return MEMORY_E;
}
#endif
algoSz = SetAlgoID(ECDSAk, algo, keyType, curveSz);
lenSz = SetLength(pubSz + 1, len);
@ -4798,6 +4838,12 @@ static int SetEccPublicKey(byte* output, ecc_key* key)
XMEMCPY(output + idx, pub, pubSz);
idx += pubSz;
#ifdef CYASSL_SMALL_STACK
XFREE(algo, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(curve, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(pub, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return idx;
}