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/*
* rc2.c : Source code for the RC2 block cipher
*
* Part of the Python Cryptography Toolkit
*
* ===================================================================
* This file appears to contain code from the ARC2 implementation
* "rc2.c" implementation (the "Original Code"), with modifications made
* after it was incorporated into PyCrypto (the "Modifications").
*
* To the best of our knowledge, the Original Code was placed into the
* public domain by its (anonymous) author:
*
* **********************************************************************
* * To commemorate the 1996 RSA Data Security Conference, the following *
* * code is released into the public domain by its author. Prost! *
* * *
* * This cipher uses 16-bit words and little-endian byte ordering. *
* * I wonder which processor it was optimized for? *
* * *
* * Thanks to CodeView, SoftIce, and D86 for helping bring this code to *
* * the public. *
* **********************************************************************
*
* The Modifications to this file are dedicated to the public domain.
* To the extent that dedication to the public domain is not available,
* everyone is granted a worldwide, perpetual, royalty-free,
* non-exclusive license to exercise all rights associated with the
* contents of this file for any purpose whatsoever. No rights are
* reserved.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
* ===================================================================
*
*/
#include "pycrypto_common.h"
#include <string.h>
#define MODULE_NAME _ARC2
#define BLOCK_SIZE 8
#define KEY_SIZE 0
#define PCT_ARC2_MODULE /* Defined to get ARC2's additional keyword arguments */
typedef uint32_t U32;
typedef uint16_t U16;
typedef uint8_t U8;
typedef struct
{
U16 xkey[64];
int effective_keylen;
} block_state;
static void
block_encrypt(block_state *self, U8 *in, U8 *out)
{
U16 x76, x54, x32, x10;
int i;
x76 = (in[7] << 8) + in[6];
x54 = (in[5] << 8) + in[4];
x32 = (in[3] << 8) + in[2];
x10 = (in[1] << 8) + in[0];
for (i = 0; i < 16; i++)
{
x10 += (x32 & ~x76) + (x54 & x76) + self->xkey[4*i+0];
x10 = (x10 << 1) + (x10 >> 15 & 1);
x32 += (x54 & ~x10) + (x76 & x10) + self->xkey[4*i+1];
x32 = (x32 << 2) + (x32 >> 14 & 3);
x54 += (x76 & ~x32) + (x10 & x32) + self->xkey[4*i+2];
x54 = (x54 << 3) + (x54 >> 13 & 7);
x76 += (x10 & ~x54) + (x32 & x54) + self->xkey[4*i+3];
x76 = (x76 << 5) + (x76 >> 11 & 31);
if (i == 4 || i == 10) {
x10 += self->xkey[x76 & 63];
x32 += self->xkey[x10 & 63];
x54 += self->xkey[x32 & 63];
x76 += self->xkey[x54 & 63];
}
}
out[0] = (U8)x10;
out[1] = (U8)(x10 >> 8);
out[2] = (U8)x32;
out[3] = (U8)(x32 >> 8);
out[4] = (U8)x54;
out[5] = (U8)(x54 >> 8);
out[6] = (U8)x76;
out[7] = (U8)(x76 >> 8);
}
static void
block_decrypt(block_state *self, U8 *in, U8 *out)
{
U16 x76, x54, x32, x10;
int i;
x76 = (in[7] << 8) + in[6];
x54 = (in[5] << 8) + in[4];
x32 = (in[3] << 8) + in[2];
x10 = (in[1] << 8) + in[0];
i = 15;
do {
x76 &= 65535;
x76 = (x76 << 11) + (x76 >> 5);
x76 -= (x10 & ~x54) + (x32 & x54) + self->xkey[4*i+3];
x54 &= 65535;
x54 = (x54 << 13) + (x54 >> 3);
x54 -= (x76 & ~x32) + (x10 & x32) + self->xkey[4*i+2];
x32 &= 65535;
x32 = (x32 << 14) + (x32 >> 2);
x32 -= (x54 & ~x10) + (x76 & x10) + self->xkey[4*i+1];
x10 &= 65535;
x10 = (x10 << 15) + (x10 >> 1);
x10 -= (x32 & ~x76) + (x54 & x76) + self->xkey[4*i+0];
if (i == 5 || i == 11) {
x76 -= self->xkey[x54 & 63];
x54 -= self->xkey[x32 & 63];
x32 -= self->xkey[x10 & 63];
x10 -= self->xkey[x76 & 63];
}
} while (i--);
out[0] = (U8)x10;
out[1] = (U8)(x10 >> 8);
out[2] = (U8)x32;
out[3] = (U8)(x32 >> 8);
out[4] = (U8)x54;
out[5] = (U8)(x54 >> 8);
out[6] = (U8)x76;
out[7] = (U8)(x76 >> 8);
}
static void
block_init(block_state *self, U8 *key, int keylength)
{
U8 x;
U16 i;
/* 256-entry permutation table, probably derived somehow from pi */
static const U8 permute[256] = {
217,120,249,196, 25,221,181,237, 40,233,253,121, 74,160,216,157,
198,126, 55,131, 43,118, 83,142, 98, 76,100,136, 68,139,251,162,
23,154, 89,245,135,179, 79, 19, 97, 69,109,141, 9,129,125, 50,
189,143, 64,235,134,183,123, 11,240,149, 33, 34, 92,107, 78,130,
84,214,101,147,206, 96,178, 28,115, 86,192, 20,167,140,241,220,
18,117,202, 31, 59,190,228,209, 66, 61,212, 48,163, 60,182, 38,
111,191, 14,218, 70,105, 7, 87, 39,242, 29,155,188,148, 67, 3,
248, 17,199,246,144,239, 62,231, 6,195,213, 47,200,102, 30,215,
8,232,234,222,128, 82,238,247,132,170,114,172, 53, 77,106, 42,
150, 26,210,113, 90, 21, 73,116, 75,159,208, 94, 4, 24,164,236,
194,224, 65,110, 15, 81,203,204, 36,145,175, 80,161,244,112, 57,
153,124, 58,133, 35,184,180,122,252, 2, 54, 91, 37, 85,151, 49,
45, 93,250,152,227,138,146,174, 5,223, 41, 16,103,108,186,201,
211, 0,230,207,225,158,168, 44, 99, 22, 1, 63, 88,226,137,169,
13, 56, 52, 27,171, 51,255,176,187, 72, 12, 95,185,177,205, 46,
197,243,219, 71,229,165,156,119, 10,166, 32,104,254,127,193,173
};
if ((U32)keylength > sizeof(self->xkey)) {
PyErr_SetString(PyExc_ValueError,
"ARC2 key length must be less than 128 bytes");
return;
}
memcpy(self->xkey, key, keylength);
/* Phase 1: Expand input key to 128 bytes */
if (keylength < 128) {
i = 0;
x = ((U8 *)self->xkey)[keylength-1];
do {
x = permute[(x + ((U8 *)self->xkey)[i++]) & 255];
((U8 *)self->xkey)[keylength++] = x;
} while (keylength < 128);
}
/* Phase 2 - reduce effective key size to "effective_keylen" */
keylength = (self->effective_keylen+7) >> 3;
i = 128-keylength;
x = permute[((U8 *)self->xkey)[i] & (255 >>
(7 &
((self->effective_keylen %8 ) ? 8-(self->effective_keylen%8): 0))
)];
((U8 *)self->xkey)[i] = x;
while (i--) {
x = permute[ x ^ ((U8 *)self->xkey)[i+keylength] ];
((U8 *)self->xkey)[i] = x;
}
/* Phase 3 - copy to self->xkey in little-endian order */
i = 63;
do {
self->xkey[i] = ((U8 *)self->xkey)[2*i] +
(((U8 *)self->xkey)[2*i+1] << 8);
} while (i--);
}
static void
block_finalize(block_state* self)
{
}
#include "block_template.c"
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