mirror of
https://github.com/michaelrsweet/pdfio.git
synced 2024-11-16 18:38:23 +01:00
114 lines
3.0 KiB
C
114 lines
3.0 KiB
C
//
|
||
// RC4 functions for PDFio.
|
||
//
|
||
// Copyright © 2021 by Michael R Sweet.
|
||
//
|
||
// Original code by Tim Martin
|
||
// Copyright © 1999 by Carnegie Mellon University, All Rights Reserved
|
||
//
|
||
// Permission to use, copy, modify, and distribute this software and its
|
||
// documentation for any purpose and without fee is hereby granted,
|
||
// provided that the above copyright notice appear in all copies and that
|
||
// both that copyright notice and this permission notice appear in
|
||
// supporting documentation, and that the name of Carnegie Mellon
|
||
// University not be used in advertising or publicity pertaining to
|
||
// distribution of the software without specific, written prior
|
||
// permission.
|
||
//
|
||
// CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
|
||
// THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
|
||
// FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE FOR
|
||
// ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
|
||
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
||
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
|
||
// OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
||
//
|
||
|
||
#include "pdfio-private.h"
|
||
|
||
|
||
//
|
||
// '_pdfioCryptoRC4Init()' - Initialize an RC4 context with the specified key.
|
||
//
|
||
|
||
void
|
||
_pdfioCryptoRC4Init(
|
||
_pdfio_rc4_t *ctx, // IO - Context
|
||
const uint8_t *key, // I - Key
|
||
size_t keylen) // I - Length of key
|
||
{
|
||
size_t i; // Looping var
|
||
uint8_t j, // S box counter
|
||
tmp; // Temporary variable
|
||
|
||
|
||
// Fill in linearly s0=0, s1=1, ...
|
||
for (i = 0; i < 256; i ++)
|
||
ctx->sbox[i] = (uint8_t)i;
|
||
|
||
for (i = 0, j = 0; i < 256; i ++)
|
||
{
|
||
// j = (j + Si + Ki) mod 256
|
||
j += ctx->sbox[i] + key[i % keylen];
|
||
|
||
// Swap Si and Sj...
|
||
tmp = ctx->sbox[i];
|
||
ctx->sbox[i] = ctx->sbox[j];
|
||
ctx->sbox[j] = tmp;
|
||
}
|
||
|
||
// Initialize counters to 0 and return...
|
||
ctx->i = 0;
|
||
ctx->j = 0;
|
||
}
|
||
|
||
|
||
//
|
||
// '_pdfioCryptoRC4Crypt()' - De/encrypt the given buffer.
|
||
//
|
||
// "inbuffer" and "outbuffer" can point to the same memory.
|
||
//
|
||
|
||
size_t // O - Number of output bytes
|
||
_pdfioCryptoRC4Crypt(
|
||
_pdfio_rc4_t *ctx, // I - Context
|
||
uint8_t *outbuffer, // I - Output buffer
|
||
const uint8_t *inbuffer, // I - Input buffer
|
||
size_t len) // I - Size of buffers
|
||
{
|
||
uint8_t tmp, // Swap variable
|
||
i, j, // Looping vars
|
||
t; // Current S box
|
||
size_t outbytes = len; // Number of output bytes
|
||
|
||
|
||
// Loop through the entire buffer...
|
||
i = ctx->i;
|
||
j = ctx->j;
|
||
|
||
while (len > 0)
|
||
{
|
||
// Get the next S box indices...
|
||
i ++;
|
||
j += ctx->sbox[i];
|
||
|
||
// Swap Si and Sj...
|
||
tmp = ctx->sbox[i];
|
||
ctx->sbox[i] = ctx->sbox[j];
|
||
ctx->sbox[j] = tmp;
|
||
|
||
// Get the S box index for this byte...
|
||
t = ctx->sbox[i] + ctx->sbox[j];
|
||
|
||
// Encrypt using the S box...
|
||
*outbuffer++ = *inbuffer++ ^ ctx->sbox[t];
|
||
len --;
|
||
}
|
||
|
||
// Copy current S box indices back to context...
|
||
ctx->i = i;
|
||
ctx->j = j;
|
||
|
||
return (outbytes);
|
||
}
|