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Refactor crypto callback to have separate input/output pointers. Add initial writing support.

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This commit is contained in:
Michael R Sweet
2021-10-12 09:13:30 -04:00
parent 0caea44f32
commit c24243a2bc
7 changed files with 151 additions and 28 deletions
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50
pdfio-aes.c
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@@ -170,23 +170,34 @@ _pdfioCryptoAESInit(
//
// '_pdfioCryptoAESDecrypt()' - Decrypt a block of bytes with AES.
//
// "inbuffer" and "outbuffer" can point to the same memory.
//
void
_pdfioCryptoAESDecrypt(
_pdfio_aes_t *ctx, // I - AES context
uint8_t *buffer, // I - Buffer
uint8_t *outbuffer, // I - Output buffer
const uint8_t *inbuffer, // I - Input buffer
size_t len) // I - Number of bytes to decrypt
{
uint8_t next_iv[16]; // Next IV value
if (inbuffer != outbuffer)
{
// Not the most efficient, but we can optimize later - the sample AES code
// manipulates the data directly in memory and doesn't support separate
// input and output buffers...
memcpy(outbuffer, inbuffer, len);
}
while (len > 15)
{
memcpy(next_iv, buffer, 16);
InvCipher((state_t *)buffer, ctx);
XorWithIv(buffer, ctx->iv);
memcpy(next_iv, outbuffer, 16);
InvCipher((state_t *)outbuffer, ctx);
XorWithIv(outbuffer, ctx->iv);
memcpy(ctx->iv, next_iv, 16);
buffer += 16;
outbuffer += 16;
len -= 16;
}
@@ -196,14 +207,14 @@ _pdfioCryptoAESDecrypt(
uint8_t temp[16]; // Temporary buffer
memset(temp, 16 - len, sizeof(temp));
memcpy(temp, buffer, len);
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(buffer, temp, len);
memcpy(outbuffer, temp, len);
}
}
@@ -211,23 +222,34 @@ _pdfioCryptoAESDecrypt(
//
// '_pdfioCryptoAESEncrypt()' - Encrypt a block of bytes with AES.
//
// "inbuffer" and "outbuffer" can point to the same memory.
//
void
_pdfioCryptoAESEncrypt(
_pdfio_aes_t *ctx, // I - AES context
uint8_t *buffer, // I - Buffer
uint8_t *outbuffer, // I - Output buffer
const uint8_t *inbuffer, // I - Input buffer
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)
{
// Not the most efficient, but we can optimize later - the sample AES code
// manipulates the data directly in memory and doesn't support separate
// input and output buffers...
memcpy(outbuffer, inbuffer, len);
}
while (len > 15)
{
XorWithIv(buffer, iv);
Cipher((state_t*)buffer, ctx);
iv = buffer;
buffer += 16;
XorWithIv(outbuffer, iv);
Cipher((state_t*)outbuffer, ctx);
iv = outbuffer;
outbuffer += 16;
len -= 16;
}
@@ -235,13 +257,13 @@ _pdfioCryptoAESEncrypt(
{
// Pad the final buffer with (16 - len)...
memset(temp, 16 - len, sizeof(temp));
memcpy(temp, buffer, len);
memcpy(temp, outbuffer, len);
XorWithIv(temp, iv);
Cipher((state_t*)temp, ctx);
iv = temp;
memcpy(buffer, temp, len);
memcpy(outbuffer, temp, len);
}
/* store Iv in ctx for next call */