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asn: refactoring SetRsaPublicKey to reduce stack usage: 553 bytes - pointers size moved to the heap.

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--- variable n moved to the heap (517 bytes saved)
--- variable e moved to the heap (16 bytes saved)
--- variable algo moved to the heap (20 bytes saved)
This commit is contained in:
Moisés Guimarães 2014-06-27 11:58:18 -03:00
parent 4aab92c982
commit 1cd81c1bb6
1 changed files with 61 additions and 6 deletions
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67
ctaocrypt/src/asn.c
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@ -4854,9 +4854,15 @@ static int SetEccPublicKey(byte* output, ecc_key* key)
/* Write a public RSA key to output */
static int SetRsaPublicKey(byte* output, RsaKey* key)
{
#ifdef CYASSL_SMALL_STACK
byte* n = NULL;
byte* e = NULL;
byte* algo = NULL;
#else
byte n[MAX_RSA_INT_SZ];
byte e[MAX_RSA_E_SZ];
byte algo[MAX_ALGO_SZ];
#endif
byte seq[MAX_SEQ_SZ];
byte len[MAX_LENGTH_SZ + 1]; /* trailing 0 */
int nSz;
@ -4870,40 +4876,83 @@ static int SetRsaPublicKey(byte* output, RsaKey* key)
int err;
/* n */
#ifdef CYASSL_SMALL_STACK
n = (byte*)XMALLOC(MAX_RSA_INT_SZ, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (n == NULL)
return MEMORY_E;
#endif
leadingBit = mp_leading_bit(&key->n);
rawLen = mp_unsigned_bin_size(&key->n) + leadingBit;
n[0] = ASN_INTEGER;
nSz = SetLength(rawLen, n + 1) + 1; /* int tag */
if ( (nSz + rawLen) < (int)sizeof(n)) {
if ( (nSz + rawLen) < MAX_RSA_INT_SZ) {
if (leadingBit)
n[nSz] = 0;
err = mp_to_unsigned_bin(&key->n, n + nSz + leadingBit);
if (err == MP_OKAY)
nSz += rawLen;
else
else {
#ifdef CYASSL_SMALL_STACK
XFREE(n, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return MP_TO_E;
}
}
else
else {
#ifdef CYASSL_SMALL_STACK
XFREE(n, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return BUFFER_E;
}
/* e */
#ifdef CYASSL_SMALL_STACK
e = (byte*)XMALLOC(MAX_RSA_E_SZ, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (e == NULL) {
#ifdef CYASSL_SMALL_STACK
XFREE(n, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return MEMORY_E;
}
#endif
leadingBit = mp_leading_bit(&key->e);
rawLen = mp_unsigned_bin_size(&key->e) + leadingBit;
e[0] = ASN_INTEGER;
eSz = SetLength(rawLen, e + 1) + 1; /* int tag */
if ( (eSz + rawLen) < (int)sizeof(e)) {
if ( (eSz + rawLen) < MAX_RSA_E_SZ) {
if (leadingBit)
e[eSz] = 0;
err = mp_to_unsigned_bin(&key->e, e + eSz + leadingBit);
if (err == MP_OKAY)
eSz += rawLen;
else
else {
#ifdef CYASSL_SMALL_STACK
XFREE(n, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(e, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return MP_TO_E;
}
}
else
else {
#ifdef CYASSL_SMALL_STACK
XFREE(n, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(e, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return BUFFER_E;
}
#ifdef CYASSL_SMALL_STACK
algo = (byte*)XMALLOC(MAX_ALGO_SZ, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (algo == NULL) {
XFREE(n, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(e, NULL, DYNAMIC_TYPE_TMP_BUFFER);
return MEMORY_E;
}
#endif
/* headers */
algoSz = SetAlgoID(RSAk, algo, keyType, 0);
@ -4932,6 +4981,12 @@ static int SetRsaPublicKey(byte* output, RsaKey* key)
XMEMCPY(output + idx, e, eSz);
idx += eSz;
#ifdef CYASSL_SMALL_STACK
XFREE(n, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(e, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(algo, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return idx;
}