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This commit is contained in:
Michael R Sweet
2021-10-15 10:40:42 -04:00
parent 493fbca31c
commit ea126c7e8d
2 changed files with 14 additions and 29 deletions
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37
pdfio-aes.c
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@@ -126,6 +126,7 @@ _pdfioCryptoAESInit(
{
if ((i % nwords) == 0)
{
// TODO: Optimize to shift and lookup S box in one step
// Shifts word left once - [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
tempa[0] = rkptr[-3];
tempa[1] = rkptr[-2];
@@ -150,12 +151,14 @@ _pdfioCryptoAESInit(
}
else
{
// Use unshifted values without S-box...
tempa[0] = rkptr[-4];
tempa[1] = rkptr[-3];
tempa[2] = rkptr[-2];
tempa[3] = rkptr[-1];
}
// TODO: Optimize to incorporate this into previous steps
*rkptr++ = *rkptr0++ ^ tempa[0];
*rkptr++ = *rkptr0++ ^ tempa[1];
*rkptr++ = *rkptr0++ ^ tempa[2];
@@ -171,7 +174,8 @@ _pdfioCryptoAESInit(
//
// '_pdfioCryptoAESDecrypt()' - Decrypt a block of bytes with AES.
//
// "inbuffer" and "outbuffer" can point to the same memory.
// "inbuffer" and "outbuffer" can point to the same memory. Length must be a
// multiple of 16 bytes (excess is not decrypted).
//
void
@@ -201,29 +205,14 @@ _pdfioCryptoAESDecrypt(
outbuffer += 16;
len -= 16;
}
if (len > 0)
{
// Pad the final buffer with (16 - len)...
uint8_t temp[16]; // Temporary buffer
memset(temp, 16 - len, sizeof(temp));
memcpy(temp, outbuffer, len);
memcpy(next_iv, temp, 16);
InvCipher((state_t *)temp, ctx);
XorWithIv(temp, ctx->iv);
memcpy(ctx->iv, next_iv, 16);
memcpy(outbuffer, temp, len);
}
}
//
// '_pdfioCryptoAESEncrypt()' - Encrypt a block of bytes with AES.
//
// "inbuffer" and "outbuffer" can point to the same memory.
// "inbuffer" and "outbuffer" can point to the same memory. "outbuffer" must
// be a multiple of 16 bytes.
//
void
@@ -234,7 +223,6 @@ _pdfioCryptoAESEncrypt(
size_t len) // I - Number of bytes to decrypt
{
uint8_t *iv = ctx->iv; // Current IV for CBC
uint8_t temp[16]; // Temporary buffer
if (inbuffer != outbuffer)
@@ -257,14 +245,11 @@ _pdfioCryptoAESEncrypt(
if (len > 0)
{
// Pad the final buffer with (16 - len)...
memset(temp, 16 - len, sizeof(temp));
memcpy(temp, outbuffer, len);
memset(outbuffer + len, 16 - len, 16 - len);
XorWithIv(temp, iv);
Cipher((state_t*)temp, ctx);
iv = temp;
memcpy(outbuffer, temp, len);
XorWithIv(outbuffer, iv);
Cipher((state_t*)outbuffer, ctx);
iv = outbuffer;
}
/* store Iv in ctx for next call */