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AES-CTR: improve performance when multiple blocks

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When in and out aren't the same pointer, for multiples of block size
input:
  - generate the counters into the output buffer
  - encrypt output buffer
  - XOR in the input
Faster than encrypting a block at a time.
This commit is contained in:
Sean Parkinson
2022-07-08 09:56:20 +10:00
parent 4e1e1e922a
commit 2bfac42d65
1 changed files with 45 additions and 21 deletions
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66
wolfcrypt/src/aes.c
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@ -4470,30 +4470,54 @@ int wc_AesSetIV(Aes* aes, const byte* iv)
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Add("wc_AesCtrEncrypt scratch", scratch, AES_BLOCK_SIZE);
#endif
/* do as many block size ops as possible */
while (sz >= AES_BLOCK_SIZE) {
#ifdef XTRANSFORM_AESCTRBLOCK
XTRANSFORM_AESCTRBLOCK(aes, out, in);
#else
ret = wc_AesEncrypt(aes, (byte*)aes->reg, scratch);
if (ret != 0) {
ForceZero(scratch, AES_BLOCK_SIZE);
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Check(scratch, AES_BLOCK_SIZE);
#endif
return ret;
#if defined(HAVE_AES_ECB) && !defined(WOLFSSL_PIC32MZ_CRYPT) && \
!defined(XTRANSFORM_AESCTRBLOCK)
if (in != out && sz >= AES_BLOCK_SIZE) {
int blocks = sz / AES_BLOCK_SIZE;
byte* counter = (byte*)aes->reg;
byte* c = out;
while (blocks--) {
XMEMCPY(c, counter, AES_BLOCK_SIZE);
c += AES_BLOCK_SIZE;
IncrementAesCounter(counter);
}
xorbuf(scratch, in, AES_BLOCK_SIZE);
XMEMCPY(out, scratch, AES_BLOCK_SIZE);
#endif
IncrementAesCounter((byte*)aes->reg);
out += AES_BLOCK_SIZE;
in += AES_BLOCK_SIZE;
sz -= AES_BLOCK_SIZE;
aes->left = 0;
/* reset number of blocks and then do encryption */
blocks = sz / AES_BLOCK_SIZE;
wc_AesEcbEncrypt(aes, out, out, AES_BLOCK_SIZE * blocks);
xorbuf(out, in, AES_BLOCK_SIZE * blocks);
in += AES_BLOCK_SIZE * blocks;
out += AES_BLOCK_SIZE * blocks;
sz -= blocks * AES_BLOCK_SIZE;
}
else
#endif
{
/* do as many block size ops as possible */
while (sz >= AES_BLOCK_SIZE) {
#ifdef XTRANSFORM_AESCTRBLOCK
XTRANSFORM_AESCTRBLOCK(aes, out, in);
#else
ret = wc_AesEncrypt(aes, (byte*)aes->reg, scratch);
if (ret != 0) {
ForceZero(scratch, AES_BLOCK_SIZE);
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Check(scratch, AES_BLOCK_SIZE);
#endif
return ret;
}
xorbuf(scratch, in, AES_BLOCK_SIZE);
XMEMCPY(out, scratch, AES_BLOCK_SIZE);
#endif
IncrementAesCounter((byte*)aes->reg);
out += AES_BLOCK_SIZE;
in += AES_BLOCK_SIZE;
sz -= AES_BLOCK_SIZE;
aes->left = 0;
}
ForceZero(scratch, AES_BLOCK_SIZE);
}
ForceZero(scratch, AES_BLOCK_SIZE);
/* handle non block size remaining and store unused byte count in left */
if (sz) {