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tls: refactoring CyaSSL_make_eap_keys to reduce stack usage:

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--- variable seed moved to the heap (up to 64 bytes saved)
This commit is contained in:
Moisés Guimarães
2014-08-02 17:55:13 -03:00
parent 04dd56df79
commit 32847ee78e
1 changed files with 32 additions and 17 deletions
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49
src/tls.c
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@ -406,16 +406,16 @@ static const byte key_label [KEY_LABEL_SZ + 1] = "key expansion";
int DeriveTlsKeys(CYASSL* ssl)
{
int ret;
int length = 2 * ssl->specs.hash_size +
2 * ssl->specs.key_size +
2 * ssl->specs.iv_size;
int ret;
int length = 2 * ssl->specs.hash_size +
2 * ssl->specs.key_size +
2 * ssl->specs.iv_size;
#ifdef CYASSL_SMALL_STACK
byte* seed;
byte* key_data;
byte* seed;
byte* key_data;
#else
byte seed[SEED_LEN];
byte key_data[MAX_PRF_DIG];
byte seed[SEED_LEN];
byte key_data[MAX_PRF_DIG];
#endif
#ifdef CYASSL_SMALL_STACK
@ -451,11 +451,11 @@ int DeriveTlsKeys(CYASSL* ssl)
int MakeTlsMasterSecret(CYASSL* ssl)
{
int ret;
int ret;
#ifdef CYASSL_SMALL_STACK
byte* seed;
#else
byte seed[SEED_LEN];
byte seed[SEED_LEN];
#endif
#ifdef CYASSL_SMALL_STACK
@ -498,20 +498,35 @@ int MakeTlsMasterSecret(CYASSL* ssl)
int CyaSSL_make_eap_keys(CYASSL* ssl, void* msk, unsigned int len,
const char* label)
{
byte seed[SEED_LEN];
int ret;
#ifdef CYASSL_SMALL_STACK
byte* seed;
#else
byte seed[SEED_LEN];
#endif
#ifdef CYASSL_SMALL_STACK
seed = (byte*)XMALLOC(SEED_LEN, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (seed == NULL)
return MEMORY_E;
#endif
/*
* As per RFC-5281, the order of the client and server randoms is reversed
* from that used by the TLS protocol to derive keys.
*/
XMEMCPY(seed, ssl->arrays->clientRandom, RAN_LEN);
XMEMCPY(&seed[RAN_LEN], ssl->arrays->serverRandom, RAN_LEN);
XMEMCPY(seed, ssl->arrays->clientRandom, RAN_LEN);
XMEMCPY(seed + RAN_LEN, ssl->arrays->serverRandom, RAN_LEN);
return PRF((byte*)msk, len,
ssl->arrays->masterSecret, SECRET_LEN,
(const byte *)label, (word32)strlen(label),
seed, SEED_LEN, IsAtLeastTLSv1_2(ssl), ssl->specs.mac_algorithm);
ret = PRF((byte*)msk, len, ssl->arrays->masterSecret, SECRET_LEN,
(const byte *)label, (word32)strlen(label), seed, SEED_LEN,
IsAtLeastTLSv1_2(ssl), ssl->specs.mac_algorithm);
#ifdef CYASSL_SMALL_STACK
XFREE(seed, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ret;
}