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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifdef FREEBL_NO_DEPEND
#include "stubs.h"
#endif
#include "prtypes.h"
#include "blapit.h"
#include "blapii.h"
#include "ctr.h"
#include "pkcs11t.h"
#include "secerr.h"
SECStatus
CTR_InitContext(CTRContext *ctr, void *context, freeblCipherFunc cipher,
const unsigned char *param, unsigned int blocksize)
{
const CK_AES_CTR_PARAMS *ctrParams = (const CK_AES_CTR_PARAMS *)param;
if (ctrParams->ulCounterBits == 0 ||
ctrParams->ulCounterBits > blocksize * PR_BITS_PER_BYTE) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* Invariant: 0 < ctr->bufPtr <= blocksize */
ctr->bufPtr = blocksize; /* no unused data in the buffer */
ctr->cipher = cipher;
ctr->context = context;
ctr->counterBits = ctrParams->ulCounterBits;
if (blocksize > sizeof(ctr->counter) ||
blocksize > sizeof(ctrParams->cb)) {
PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
return SECFailure;
}
PORT_Memcpy(ctr->counter, ctrParams->cb, blocksize);
return SECSuccess;
}
CTRContext *
CTR_CreateContext(void *context, freeblCipherFunc cipher,
const unsigned char *param, unsigned int blocksize)
{
CTRContext *ctr;
SECStatus rv;
/* first fill in the Counter context */
ctr = PORT_ZNew(CTRContext);
if (ctr == NULL) {
return NULL;
}
rv = CTR_InitContext(ctr, context, cipher, param, blocksize);
if (rv != SECSuccess) {
CTR_DestroyContext(ctr, PR_TRUE);
ctr = NULL;
}
return ctr;
}
void
CTR_DestroyContext(CTRContext *ctr, PRBool freeit)
{
PORT_Memset(ctr, 0, sizeof(CTRContext));
if (freeit) {
PORT_Free(ctr);
}
}
/*
* Used by counter mode. Increment the counter block. Not all bits in the
* counter block are part of the counter, counterBits tells how many bits
* are part of the counter. The counter block is blocksize long. It's a
* big endian value.
*
* XXX Does not handle counter rollover.
*/
static void
ctr_GetNextCtr(unsigned char *counter, unsigned int counterBits,
unsigned int blocksize)
{
unsigned char *counterPtr = counter + blocksize - 1;
unsigned char mask, count;
PORT_Assert(counterBits <= blocksize*PR_BITS_PER_BYTE);
while (counterBits >= PR_BITS_PER_BYTE) {
if (++(*(counterPtr--))) {
return;
}
counterBits -= PR_BITS_PER_BYTE;
}
if (counterBits == 0) {
return;
}
/* increment the final partial byte */
mask = (1 << counterBits)-1;
count = ++(*counterPtr) & mask;
*counterPtr = ((*counterPtr) & ~mask) | count;
return;
}
static void
ctr_xor(unsigned char *target, const unsigned char *x,
const unsigned char *y, unsigned int count)
{
unsigned int i;
for (i=0; i < count; i++) {
*target++ = *x++ ^ *y++;
}
}
SECStatus
CTR_Update(CTRContext *ctr, unsigned char *outbuf,
unsigned int *outlen, unsigned int maxout,
const unsigned char *inbuf, unsigned int inlen,
unsigned int blocksize)
{
unsigned int tmp;
SECStatus rv;
if (maxout < inlen) {
*outlen = inlen;
PORT_SetError(SEC_ERROR_OUTPUT_LEN);
return SECFailure;
}
*outlen = 0;
if (ctr->bufPtr != blocksize) {
unsigned int needed = PR_MIN(blocksize-ctr->bufPtr, inlen);
ctr_xor(outbuf, inbuf, ctr->buffer+ctr->bufPtr, needed);
ctr->bufPtr += needed;
outbuf += needed;
inbuf += needed;
*outlen += needed;
inlen -= needed;
if (inlen == 0) {
return SECSuccess;
}
PORT_Assert(ctr->bufPtr == blocksize);
}
while (inlen >= blocksize) {
rv = (*ctr->cipher)(ctr->context, ctr->buffer, &tmp, blocksize,
ctr->counter, blocksize, blocksize);
ctr_GetNextCtr(ctr->counter, ctr->counterBits, blocksize);
if (rv != SECSuccess) {
return SECFailure;
}
ctr_xor(outbuf, inbuf, ctr->buffer, blocksize);
outbuf += blocksize;
inbuf += blocksize;
*outlen += blocksize;
inlen -= blocksize;
}
if (inlen == 0) {
return SECSuccess;
}
rv = (*ctr->cipher)(ctr->context, ctr->buffer, &tmp, blocksize,
ctr->counter, blocksize, blocksize);
ctr_GetNextCtr(ctr->counter, ctr->counterBits, blocksize);
if (rv != SECSuccess) {
return SECFailure;
}
ctr_xor(outbuf, inbuf, ctr->buffer, inlen);
ctr->bufPtr = inlen;
*outlen += inlen;
return SECSuccess;
}
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