/* rijndael_key_expansion
*
* Generate the expanded key from the key input by the user.
*/
static SECStatus
rijndael_key_expansion(AESContext *cx, const unsigned char *key, unsigned int Nk)
{
unsigned int i;
PRUint32 *W;
PRUint32 *pW;
PRUint32 tmp;
unsigned int round_key_words = cx->Nb * (cx->Nr + 1);
if (Nk == 7)
return rijndael_key_expansion7(cx, key, Nk);
W = cx->expandedKey;
/* The first Nk words contain the input cipher key */
memcpy(W, key, Nk * 4);
i = Nk;
pW = W + i - 1;
/* Loop over all sets of Nk words, except the last */
while (i < round_key_words - Nk) {
tmp = *pW++;
tmp = SUBBYTE(ROTBYTE(tmp)) ^ Rcon[i / Nk - 1];
*pW = W[i++ - Nk] ^ tmp;
tmp = *pW++; *pW = W[i++ - Nk] ^ tmp;
tmp = *pW++; *pW = W[i++ - Nk] ^ tmp;
tmp = *pW++; *pW = W[i++ - Nk] ^ tmp;
if (Nk == 4)
continue;
switch (Nk) {
case 8: tmp = *pW++; tmp = SUBBYTE(tmp); *pW = W[i++ - Nk] ^ tmp;
case 7: tmp = *pW++; *pW = W[i++ - Nk] ^ tmp;
case 6: tmp = *pW++; *pW = W[i++ - Nk] ^ tmp;
case 5: tmp = *pW++; *pW = W[i++ - Nk] ^ tmp;
}
}
/* Generate the last word */
tmp = *pW++;
tmp = SUBBYTE(ROTBYTE(tmp)) ^ Rcon[i / Nk - 1];
*pW = W[i++ - Nk] ^ tmp;
/* There may be overflow here, if Nk % (Nb * (Nr + 1)) > 0. However,
* since the above loop generated all but the last Nk key words, there
* is no more need for the SubByte transformation.
*/
if (Nk < 8) {
for (; i < round_key_words; ++i) {
tmp = *pW++;
*pW = W[i - Nk] ^ tmp;
}
} else {
/* except in the case when Nk == 8. Then one more SubByte may have
* to be performed, at i % Nk == 4.
*/
for (; i < round_key_words; ++i) {
tmp = *pW++;
if (i % Nk == 4)
tmp = SUBBYTE(tmp);
*pW = W[i - Nk] ^ tmp;
}
}
return SECSuccess;
}
void KeyExpansion(RijndaelContextPtr context)
{
int i;
unsigned int tmp;
//256位有32个字节，8个字长
//密钥字长
int nk = context->nk;
//明文字长
int nb = context->nb;
//轮数
int nr = context->nr;
unsigned char* keyPtr = context->cryptKey;
//nr最大为14，nb最大为8,则需要的矩阵列为nb*(nr+1)=8*15=120
//轮密钥
//unsigned long roundKey[120] = {0};
context->roundKey[0] = GETINT32(keyPtr,0,nk);//第一列
context->roundKey[1] = GETINT32(keyPtr,1,nk);//第二列
context->roundKey[2] = GETINT32(keyPtr,2,nk);//第三列
context->roundKey[3] = GETINT32(keyPtr,3,nk);//第四列
if (nk >= (KeySize_192/4))
{
context->roundKey[4] = GETINT32(keyPtr,4,nk);
context->roundKey[5] = GETINT32(keyPtr,5,nk);
}
else if (nk >= (KeySize_256/4))
{
context->roundKey[6] = GETINT32(keyPtr,6,nk);
context->roundKey[7] = GETINT32(keyPtr,7,nk);
}
//轮数为明文和密文中长度更大值的字长+4
for (i = nk;i<(nb*(nr+1)); i++)
{
tmp = context->roundKey[i-1];
if (i % nk == 0)
{
tmp = ROTL(tmp,8,32);
tmp = SUBBYTE(tmp);
tmp ^= rcon[i / nk];
}
else if ((nk > (KeySize_192/4)) && (i%4 == 0))
{
tmp = SUBBYTE(tmp);
}
context->roundKey[i] = context->roundKey[i - nk] ^ tmp;
}
//将不需要的清0
memset(&context->roundKey[nb*(nr+1)],0,sizeof(context->roundKey) - sizeof(context->roundKey[0]) * (nb*(nr+1)));
//轮密钥还可以加强,扩展
}
/* rijndael_key_expansion7
*
* Generate the expanded key from the key input by the user.
* XXX
* Nk == 7 (224 key bits) is a weird case. Since Nk > 6, an added SubByte
* transformation is done periodically. The period is every 4 bytes, and
* since 7%4 != 0 this happens at different times for each key word (unlike
* Nk == 8 where it happens twice in every key word, in the same positions).
* For now, I'm implementing this case "dumbly", w/o any unrolling.
*/
static SECStatus
rijndael_key_expansion7(AESContext *cx, const unsigned char *key, unsigned int Nk)
{
unsigned int i;
PRUint32 *W;
PRUint32 *pW;
PRUint32 tmp;
W = cx->expandedKey;
/* 1. the first Nk words contain the cipher key */
memcpy(W, key, Nk * 4);
i = Nk;
/* 2. loop until full expanded key is obtained */
pW = W + i - 1;
for (; i < cx->Nb * (cx->Nr + 1); ++i) {
tmp = *pW++;
if (i % Nk == 0)
tmp = SUBBYTE(ROTBYTE(tmp)) ^ Rcon[i / Nk - 1];
else if (i % Nk == 4)
tmp = SUBBYTE(tmp);
*pW = W[i - Nk] ^ tmp;
}
return SECSuccess;
}
/**
* 将明文替换
*/
void SubByte(RijndaelContextPtr context,unsigned long state[])
{
/*
statePtr->v0 = SUBBYTE(statePtr->v0);
statePtr->v1 = SUBBYTE(statePtr->v1);
statePtr->v2 = SUBBYTE(statePtr->v2);
statePtr->v3 = SUBBYTE(statePtr->v3);
if (contextPtr->nb >= (KeySize_192/4))
{
statePtr->v4 = SUBBYTE(statePtr->v4);
statePtr->v5 = SUBBYTE(statePtr->v5);
}
if (contextPtr->nb >= (KeySize_256/4))
{
statePtr->v6 = SUBBYTE(statePtr->v6);
statePtr->v7 = SUBBYTE(statePtr->v7);
}
*/
unsigned int i;
for (i=0; i<context->nb; i++)
{
state[i] = SUBBYTE(state[i]);
}
}