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keys: refactoring DeriveKeys to reduce stack usage:

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--- variable shaOutput moved to the heap (20 bytes saved)
--- variable md5Input moved to the heap (68 bytes saved)
--- variable shaInput moved to the heap (119 bytes saved)
--- variable keyData moved to the heap (112 bytes saved)
--- variable md5 moved to the heap (sizeof(Md5) saved)
--- variable sha moved to the heap (sizeof(Sha) saved)
This commit is contained in:
Moisés Guimarães 2014-08-05 15:26:28 -07:00
parent 32847ee78e
commit 39c167710f
1 changed files with 82 additions and 35 deletions
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117
src/keys.c
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@ -2234,51 +2234,98 @@ int StoreKeys(CYASSL* ssl, const byte* keyData)
#ifndef NO_OLD_TLS
int DeriveKeys(CYASSL* ssl)
{
int length = 2 * ssl->specs.hash_size +
2 * ssl->specs.key_size +
2 * ssl->specs.iv_size;
int rounds = (length + MD5_DIGEST_SIZE - 1 ) / MD5_DIGEST_SIZE, i;
int ret = 0;
int length = 2 * ssl->specs.hash_size +
2 * ssl->specs.key_size +
2 * ssl->specs.iv_size;
int rounds = (length + MD5_DIGEST_SIZE - 1 ) / MD5_DIGEST_SIZE, i;
int ret = 0;
word32 md5InputSz = SECRET_LEN + SHA_DIGEST_SIZE;
word32 shaInputSz = KEY_PREFIX + SECRET_LEN + 2 * RAN_LEN;
word32 keyDataSz = KEY_PREFIX * MD5_DIGEST_SIZE; /* max size */
#ifdef CYASSL_SMALL_STACK
byte* shaOutput;
byte* md5Input;
byte* shaInput;
byte* keyData;
Md5* md5;
Sha* sha;
#else
byte shaOutput[SHA_DIGEST_SIZE];
byte md5Input[md5InputSz];
byte shaInput[shaInputSz];
byte keyData[keyDataSz];
Md5 md5[1];
Sha sha[1];
#endif
#ifdef CYASSL_SMALL_STACK
shaOutput = (byte*)XMALLOC(SHA_DIGEST_SIZE,
NULL, DYNAMIC_TYPE_TMP_BUFFER);
md5Input = (byte*)XMALLOC(md5InputSz, NULL, DYNAMIC_TYPE_TMP_BUFFER);
shaInput = (byte*)XMALLOC(shaInputSz, NULL, DYNAMIC_TYPE_TMP_BUFFER);
keyData = (byte*)XMALLOC(keyDataSz, NULL, DYNAMIC_TYPE_TMP_BUFFER);
md5 = (Md5*)XMALLOC(sizeof(Md5), NULL, DYNAMIC_TYPE_TMP_BUFFER);
sha = (Sha*)XMALLOC(sizeof(Sha), NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (shaOutput == NULL || md5Input == NULL || shaInput == NULL ||
keyData == NULL || md5 == NULL || sha == NULL) {
if (shaOutput) XFREE(shaOutput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (md5Input) XFREE(md5Input, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (shaInput) XFREE(shaInput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (keyData) XFREE(keyData, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (md5) XFREE(md5, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (sha) XFREE(sha, NULL, DYNAMIC_TYPE_TMP_BUFFER);
return MEMORY_E;
}
#endif
byte shaOutput[SHA_DIGEST_SIZE];
byte md5Input[SECRET_LEN + SHA_DIGEST_SIZE];
byte shaInput[KEY_PREFIX + SECRET_LEN + 2 * RAN_LEN];
Md5 md5;
Sha sha;
InitMd5(md5);
byte keyData[KEY_PREFIX * MD5_DIGEST_SIZE]; /* max size */
ret = InitSha(sha);
InitMd5(&md5);
ret = InitSha(&sha);
if (ret != 0)
return ret;
if (ret == 0) {
XMEMCPY(md5Input, ssl->arrays->masterSecret, SECRET_LEN);
XMEMCPY(md5Input, ssl->arrays->masterSecret, SECRET_LEN);
for (i = 0; i < rounds; ++i) {
int j = i + 1;
int idx = j;
for (i = 0; i < rounds; ++i) {
int j = i + 1;
int idx = j;
if (!SetPrefix(shaInput, i)) {
ret = PREFIX_ERROR;
break;
}
if (!SetPrefix(shaInput, i)) {
return PREFIX_ERROR;
XMEMCPY(shaInput + idx, ssl->arrays->masterSecret, SECRET_LEN);
idx += SECRET_LEN;
XMEMCPY(shaInput + idx, ssl->arrays->serverRandom, RAN_LEN);
idx += RAN_LEN;
XMEMCPY(shaInput + idx, ssl->arrays->clientRandom, RAN_LEN);
ShaUpdate(sha, shaInput, shaInputSz - KEY_PREFIX + j);
ShaFinal(sha, shaOutput);
XMEMCPY(md5Input + SECRET_LEN, shaOutput, SHA_DIGEST_SIZE);
Md5Update(md5, md5Input, md5InputSz);
Md5Final(md5, keyData + i * MD5_DIGEST_SIZE);
}
XMEMCPY(shaInput + idx, ssl->arrays->masterSecret, SECRET_LEN);
idx += SECRET_LEN;
XMEMCPY(shaInput + idx, ssl->arrays->serverRandom, RAN_LEN);
idx += RAN_LEN;
XMEMCPY(shaInput + idx, ssl->arrays->clientRandom, RAN_LEN);
ShaUpdate(&sha, shaInput, (word32)sizeof(shaInput) - KEY_PREFIX + j);
ShaFinal(&sha, shaOutput);
XMEMCPY(&md5Input[SECRET_LEN], shaOutput, SHA_DIGEST_SIZE);
Md5Update(&md5, md5Input, sizeof(md5Input));
Md5Final(&md5, keyData + i * MD5_DIGEST_SIZE);
if (ret == 0)
ret = StoreKeys(ssl, keyData);
}
return StoreKeys(ssl, keyData);
#ifdef CYASSL_SMALL_STACK
XFREE(shaOutput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(md5Input, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(shaInput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(keyData, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(md5, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(sha, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ret;
}