forked from KolibriOS/kolibrios
566 lines
13 KiB
C
566 lines
13 KiB
C
/*
|
|
* FIPS-197 compliant AES implementation
|
|
*
|
|
* Copyright (C) 2006-2007 Christophe Devine
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* * Redistributions of source code _must_ retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* * Redistributions in binary form may or may not reproduce the above
|
|
* copyright notice, this list of conditions and the following
|
|
* disclaimer in the documentation and/or other materials provided
|
|
* with the distribution.
|
|
* * Neither the name of XySSL nor the names of its contributors may be
|
|
* used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
|
|
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
|
|
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
|
|
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
|
|
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
|
|
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
/*
|
|
* The AES block cipher was designed by Vincent Rijmen and Joan Daemen.
|
|
*
|
|
* http://csrc.nist.gov/encryption/aes/rijndael/Rijndael.pdf
|
|
* http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
|
|
*/
|
|
|
|
#include "fitz.h"
|
|
|
|
#define aes_context fz_aes
|
|
|
|
/* AES block cipher implementation from XYSSL */
|
|
|
|
/*
|
|
* 32-bit integer manipulation macros (little endian)
|
|
*/
|
|
#ifndef GET_ULONG_LE
|
|
#define GET_ULONG_LE(n,b,i) \
|
|
{ \
|
|
(n) = ( (unsigned long) (b)[(i)] ) \
|
|
| ( (unsigned long) (b)[(i) + 1] << 8 ) \
|
|
| ( (unsigned long) (b)[(i) + 2] << 16 ) \
|
|
| ( (unsigned long) (b)[(i) + 3] << 24 ); \
|
|
}
|
|
#endif
|
|
|
|
#ifndef PUT_ULONG_LE
|
|
#define PUT_ULONG_LE(n,b,i) \
|
|
{ \
|
|
(b)[(i) ] = (unsigned char) ( (n) ); \
|
|
(b)[(i) + 1] = (unsigned char) ( (n) >> 8 ); \
|
|
(b)[(i) + 2] = (unsigned char) ( (n) >> 16 ); \
|
|
(b)[(i) + 3] = (unsigned char) ( (n) >> 24 ); \
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Forward S-box & tables
|
|
*/
|
|
static unsigned char FSb[256];
|
|
static unsigned long FT0[256];
|
|
static unsigned long FT1[256];
|
|
static unsigned long FT2[256];
|
|
static unsigned long FT3[256];
|
|
|
|
/*
|
|
* Reverse S-box & tables
|
|
*/
|
|
static unsigned char RSb[256];
|
|
static unsigned long RT0[256];
|
|
static unsigned long RT1[256];
|
|
static unsigned long RT2[256];
|
|
static unsigned long RT3[256];
|
|
|
|
/*
|
|
* Round constants
|
|
*/
|
|
static unsigned long RCON[10];
|
|
|
|
/*
|
|
* Tables generation code
|
|
*/
|
|
#define ROTL8(x) ( ( x << 8 ) & 0xFFFFFFFF ) | ( x >> 24 )
|
|
#define XTIME(x) ( ( x << 1 ) ^ ( ( x & 0x80 ) ? 0x1B : 0x00 ) )
|
|
#define MUL(x,y) ( ( x && y ) ? pow[(log[x]+log[y]) % 255] : 0 )
|
|
|
|
static int aes_init_done = 0;
|
|
|
|
static void aes_gen_tables( void )
|
|
{
|
|
int i, x, y, z;
|
|
int pow[256];
|
|
int log[256];
|
|
|
|
/*
|
|
* compute pow and log tables over GF(2^8)
|
|
*/
|
|
for( i = 0, x = 1; i < 256; i++ )
|
|
{
|
|
pow[i] = x;
|
|
log[x] = i;
|
|
x = ( x ^ XTIME( x ) ) & 0xFF;
|
|
}
|
|
|
|
/*
|
|
* calculate the round constants
|
|
*/
|
|
for( i = 0, x = 1; i < 10; i++ )
|
|
{
|
|
RCON[i] = (unsigned long) x;
|
|
x = XTIME( x ) & 0xFF;
|
|
}
|
|
|
|
/*
|
|
* generate the forward and reverse S-boxes
|
|
*/
|
|
FSb[0x00] = 0x63;
|
|
RSb[0x63] = 0x00;
|
|
|
|
for( i = 1; i < 256; i++ )
|
|
{
|
|
x = pow[255 - log[i]];
|
|
|
|
y = x; y = ( (y << 1) | (y >> 7) ) & 0xFF;
|
|
x ^= y; y = ( (y << 1) | (y >> 7) ) & 0xFF;
|
|
x ^= y; y = ( (y << 1) | (y >> 7) ) & 0xFF;
|
|
x ^= y; y = ( (y << 1) | (y >> 7) ) & 0xFF;
|
|
x ^= y ^ 0x63;
|
|
|
|
FSb[i] = (unsigned char) x;
|
|
RSb[x] = (unsigned char) i;
|
|
}
|
|
|
|
/*
|
|
* generate the forward and reverse tables
|
|
*/
|
|
for( i = 0; i < 256; i++ )
|
|
{
|
|
x = FSb[i];
|
|
y = XTIME( x ) & 0xFF;
|
|
z = ( y ^ x ) & 0xFF;
|
|
|
|
FT0[i] = ( (unsigned long) y ) ^
|
|
( (unsigned long) x << 8 ) ^
|
|
( (unsigned long) x << 16 ) ^
|
|
( (unsigned long) z << 24 );
|
|
|
|
FT1[i] = ROTL8( FT0[i] );
|
|
FT2[i] = ROTL8( FT1[i] );
|
|
FT3[i] = ROTL8( FT2[i] );
|
|
|
|
x = RSb[i];
|
|
|
|
RT0[i] = ( (unsigned long) MUL( 0x0E, x ) ) ^
|
|
( (unsigned long) MUL( 0x09, x ) << 8 ) ^
|
|
( (unsigned long) MUL( 0x0D, x ) << 16 ) ^
|
|
( (unsigned long) MUL( 0x0B, x ) << 24 );
|
|
|
|
RT1[i] = ROTL8( RT0[i] );
|
|
RT2[i] = ROTL8( RT1[i] );
|
|
RT3[i] = ROTL8( RT2[i] );
|
|
}
|
|
}
|
|
|
|
/*
|
|
* AES key schedule (encryption)
|
|
*/
|
|
void aes_setkey_enc( aes_context *ctx, const unsigned char *key, int keysize )
|
|
{
|
|
int i;
|
|
unsigned long *RK;
|
|
|
|
#if !defined(XYSSL_AES_ROM_TABLES)
|
|
if( aes_init_done == 0 )
|
|
{
|
|
aes_gen_tables();
|
|
aes_init_done = 1;
|
|
}
|
|
#endif
|
|
|
|
switch( keysize )
|
|
{
|
|
case 128: ctx->nr = 10; break;
|
|
case 192: ctx->nr = 12; break;
|
|
case 256: ctx->nr = 14; break;
|
|
default : return;
|
|
}
|
|
|
|
#if defined(PADLOCK_ALIGN16)
|
|
ctx->rk = RK = PADLOCK_ALIGN16( ctx->buf );
|
|
#else
|
|
ctx->rk = RK = ctx->buf;
|
|
#endif
|
|
|
|
for( i = 0; i < (keysize >> 5); i++ )
|
|
{
|
|
GET_ULONG_LE( RK[i], key, i << 2 );
|
|
}
|
|
|
|
switch( ctx->nr )
|
|
{
|
|
case 10:
|
|
|
|
for( i = 0; i < 10; i++, RK += 4 )
|
|
{
|
|
RK[4] = RK[0] ^ RCON[i] ^
|
|
( FSb[ ( RK[3] >> 8 ) & 0xFF ] ) ^
|
|
( FSb[ ( RK[3] >> 16 ) & 0xFF ] << 8 ) ^
|
|
( FSb[ ( RK[3] >> 24 ) & 0xFF ] << 16 ) ^
|
|
( FSb[ ( RK[3] ) & 0xFF ] << 24 );
|
|
|
|
RK[5] = RK[1] ^ RK[4];
|
|
RK[6] = RK[2] ^ RK[5];
|
|
RK[7] = RK[3] ^ RK[6];
|
|
}
|
|
break;
|
|
|
|
case 12:
|
|
|
|
for( i = 0; i < 8; i++, RK += 6 )
|
|
{
|
|
RK[6] = RK[0] ^ RCON[i] ^
|
|
( FSb[ ( RK[5] >> 8 ) & 0xFF ] ) ^
|
|
( FSb[ ( RK[5] >> 16 ) & 0xFF ] << 8 ) ^
|
|
( FSb[ ( RK[5] >> 24 ) & 0xFF ] << 16 ) ^
|
|
( FSb[ ( RK[5] ) & 0xFF ] << 24 );
|
|
|
|
RK[7] = RK[1] ^ RK[6];
|
|
RK[8] = RK[2] ^ RK[7];
|
|
RK[9] = RK[3] ^ RK[8];
|
|
RK[10] = RK[4] ^ RK[9];
|
|
RK[11] = RK[5] ^ RK[10];
|
|
}
|
|
break;
|
|
|
|
case 14:
|
|
|
|
for( i = 0; i < 7; i++, RK += 8 )
|
|
{
|
|
RK[8] = RK[0] ^ RCON[i] ^
|
|
( FSb[ ( RK[7] >> 8 ) & 0xFF ] ) ^
|
|
( FSb[ ( RK[7] >> 16 ) & 0xFF ] << 8 ) ^
|
|
( FSb[ ( RK[7] >> 24 ) & 0xFF ] << 16 ) ^
|
|
( FSb[ ( RK[7] ) & 0xFF ] << 24 );
|
|
|
|
RK[9] = RK[1] ^ RK[8];
|
|
RK[10] = RK[2] ^ RK[9];
|
|
RK[11] = RK[3] ^ RK[10];
|
|
|
|
RK[12] = RK[4] ^
|
|
( FSb[ ( RK[11] ) & 0xFF ] ) ^
|
|
( FSb[ ( RK[11] >> 8 ) & 0xFF ] << 8 ) ^
|
|
( FSb[ ( RK[11] >> 16 ) & 0xFF ] << 16 ) ^
|
|
( FSb[ ( RK[11] >> 24 ) & 0xFF ] << 24 );
|
|
|
|
RK[13] = RK[5] ^ RK[12];
|
|
RK[14] = RK[6] ^ RK[13];
|
|
RK[15] = RK[7] ^ RK[14];
|
|
}
|
|
break;
|
|
|
|
default:
|
|
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* AES key schedule (decryption)
|
|
*/
|
|
void aes_setkey_dec( aes_context *ctx, const unsigned char *key, int keysize )
|
|
{
|
|
int i, j;
|
|
aes_context cty;
|
|
unsigned long *RK;
|
|
unsigned long *SK;
|
|
|
|
switch( keysize )
|
|
{
|
|
case 128: ctx->nr = 10; break;
|
|
case 192: ctx->nr = 12; break;
|
|
case 256: ctx->nr = 14; break;
|
|
default : return;
|
|
}
|
|
|
|
#if defined(PADLOCK_ALIGN16)
|
|
ctx->rk = RK = PADLOCK_ALIGN16( ctx->buf );
|
|
#else
|
|
ctx->rk = RK = ctx->buf;
|
|
#endif
|
|
|
|
aes_setkey_enc( &cty, key, keysize );
|
|
SK = cty.rk + cty.nr * 4;
|
|
|
|
*RK++ = *SK++;
|
|
*RK++ = *SK++;
|
|
*RK++ = *SK++;
|
|
*RK++ = *SK++;
|
|
|
|
for( i = ctx->nr - 1, SK -= 8; i > 0; i--, SK -= 8 )
|
|
{
|
|
for( j = 0; j < 4; j++, SK++ )
|
|
{
|
|
*RK++ = RT0[ FSb[ ( *SK ) & 0xFF ] ] ^
|
|
RT1[ FSb[ ( *SK >> 8 ) & 0xFF ] ] ^
|
|
RT2[ FSb[ ( *SK >> 16 ) & 0xFF ] ] ^
|
|
RT3[ FSb[ ( *SK >> 24 ) & 0xFF ] ];
|
|
}
|
|
}
|
|
|
|
*RK++ = *SK++;
|
|
*RK++ = *SK++;
|
|
*RK++ = *SK++;
|
|
*RK++ = *SK++;
|
|
|
|
memset( &cty, 0, sizeof( aes_context ) );
|
|
}
|
|
|
|
#define AES_FROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3) \
|
|
{ \
|
|
X0 = *RK++ ^ FT0[ ( Y0 ) & 0xFF ] ^ \
|
|
FT1[ ( Y1 >> 8 ) & 0xFF ] ^ \
|
|
FT2[ ( Y2 >> 16 ) & 0xFF ] ^ \
|
|
FT3[ ( Y3 >> 24 ) & 0xFF ]; \
|
|
\
|
|
X1 = *RK++ ^ FT0[ ( Y1 ) & 0xFF ] ^ \
|
|
FT1[ ( Y2 >> 8 ) & 0xFF ] ^ \
|
|
FT2[ ( Y3 >> 16 ) & 0xFF ] ^ \
|
|
FT3[ ( Y0 >> 24 ) & 0xFF ]; \
|
|
\
|
|
X2 = *RK++ ^ FT0[ ( Y2 ) & 0xFF ] ^ \
|
|
FT1[ ( Y3 >> 8 ) & 0xFF ] ^ \
|
|
FT2[ ( Y0 >> 16 ) & 0xFF ] ^ \
|
|
FT3[ ( Y1 >> 24 ) & 0xFF ]; \
|
|
\
|
|
X3 = *RK++ ^ FT0[ ( Y3 ) & 0xFF ] ^ \
|
|
FT1[ ( Y0 >> 8 ) & 0xFF ] ^ \
|
|
FT2[ ( Y1 >> 16 ) & 0xFF ] ^ \
|
|
FT3[ ( Y2 >> 24 ) & 0xFF ]; \
|
|
}
|
|
|
|
#define AES_RROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3) \
|
|
{ \
|
|
X0 = *RK++ ^ RT0[ ( Y0 ) & 0xFF ] ^ \
|
|
RT1[ ( Y3 >> 8 ) & 0xFF ] ^ \
|
|
RT2[ ( Y2 >> 16 ) & 0xFF ] ^ \
|
|
RT3[ ( Y1 >> 24 ) & 0xFF ]; \
|
|
\
|
|
X1 = *RK++ ^ RT0[ ( Y1 ) & 0xFF ] ^ \
|
|
RT1[ ( Y0 >> 8 ) & 0xFF ] ^ \
|
|
RT2[ ( Y3 >> 16 ) & 0xFF ] ^ \
|
|
RT3[ ( Y2 >> 24 ) & 0xFF ]; \
|
|
\
|
|
X2 = *RK++ ^ RT0[ ( Y2 ) & 0xFF ] ^ \
|
|
RT1[ ( Y1 >> 8 ) & 0xFF ] ^ \
|
|
RT2[ ( Y0 >> 16 ) & 0xFF ] ^ \
|
|
RT3[ ( Y3 >> 24 ) & 0xFF ]; \
|
|
\
|
|
X3 = *RK++ ^ RT0[ ( Y3 ) & 0xFF ] ^ \
|
|
RT1[ ( Y2 >> 8 ) & 0xFF ] ^ \
|
|
RT2[ ( Y1 >> 16 ) & 0xFF ] ^ \
|
|
RT3[ ( Y0 >> 24 ) & 0xFF ]; \
|
|
}
|
|
|
|
/*
|
|
* AES-ECB block encryption/decryption
|
|
*/
|
|
void aes_crypt_ecb( aes_context *ctx,
|
|
int mode,
|
|
const unsigned char input[16],
|
|
unsigned char output[16] )
|
|
{
|
|
int i;
|
|
unsigned long *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;
|
|
|
|
#if defined(XYSSL_PADLOCK_C) && defined(XYSSL_HAVE_X86)
|
|
if( padlock_supports( PADLOCK_ACE ) )
|
|
{
|
|
if( padlock_xcryptecb( ctx, mode, input, output ) == 0 )
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
RK = ctx->rk;
|
|
|
|
GET_ULONG_LE( X0, input, 0 ); X0 ^= *RK++;
|
|
GET_ULONG_LE( X1, input, 4 ); X1 ^= *RK++;
|
|
GET_ULONG_LE( X2, input, 8 ); X2 ^= *RK++;
|
|
GET_ULONG_LE( X3, input, 12 ); X3 ^= *RK++;
|
|
|
|
if( mode == AES_DECRYPT )
|
|
{
|
|
for( i = (ctx->nr >> 1) - 1; i > 0; i-- )
|
|
{
|
|
AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
|
|
AES_RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );
|
|
}
|
|
|
|
AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
|
|
|
|
X0 = *RK++ ^ ( RSb[ ( Y0 ) & 0xFF ] ) ^
|
|
( RSb[ ( Y3 >> 8 ) & 0xFF ] << 8 ) ^
|
|
( RSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^
|
|
( RSb[ ( Y1 >> 24 ) & 0xFF ] << 24 );
|
|
|
|
X1 = *RK++ ^ ( RSb[ ( Y1 ) & 0xFF ] ) ^
|
|
( RSb[ ( Y0 >>8 ) & 0xFF ] << 8 ) ^
|
|
( RSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^
|
|
( RSb[ ( Y2 >> 24 ) & 0xFF ] << 24 );
|
|
|
|
X2 = *RK++ ^ ( RSb[ ( Y2 ) & 0xFF ] ) ^
|
|
( RSb[ ( Y1 >> 8 ) & 0xFF ] << 8 ) ^
|
|
( RSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^
|
|
( RSb[ ( Y3 >> 24 ) & 0xFF ] << 24 );
|
|
|
|
X3 = *RK++ ^ ( RSb[ ( Y3 ) & 0xFF ] ) ^
|
|
( RSb[ ( Y2 >> 8 ) & 0xFF ] << 8 ) ^
|
|
( RSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^
|
|
( RSb[ ( Y0 >> 24 ) & 0xFF ] << 24 );
|
|
}
|
|
else /* AES_ENCRYPT */
|
|
{
|
|
for( i = (ctx->nr >> 1) - 1; i > 0; i-- )
|
|
{
|
|
AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
|
|
AES_FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );
|
|
}
|
|
|
|
AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
|
|
|
|
X0 = *RK++ ^ ( FSb[ ( Y0 ) & 0xFF ] ) ^
|
|
( FSb[ ( Y1 >> 8 ) & 0xFF ] << 8 ) ^
|
|
( FSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^
|
|
( FSb[ ( Y3 >> 24 ) & 0xFF ] << 24 );
|
|
|
|
X1 = *RK++ ^ ( FSb[ ( Y1 ) & 0xFF ] ) ^
|
|
( FSb[ ( Y2 >> 8 ) & 0xFF ] << 8 ) ^
|
|
( FSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^
|
|
( FSb[ ( Y0 >> 24 ) & 0xFF ] << 24 );
|
|
|
|
X2 = *RK++ ^ ( FSb[ ( Y2 ) & 0xFF ] ) ^
|
|
( FSb[ ( Y3 >> 8 ) & 0xFF ] << 8 ) ^
|
|
( FSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^
|
|
( FSb[ ( Y1 >> 24 ) & 0xFF ] << 24 );
|
|
|
|
X3 = *RK++ ^ ( FSb[ ( Y3 ) & 0xFF ] ) ^
|
|
( FSb[ ( Y0 >> 8 ) & 0xFF ] << 8 ) ^
|
|
( FSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^
|
|
( FSb[ ( Y2 >> 24 ) & 0xFF ] << 24 );
|
|
}
|
|
|
|
PUT_ULONG_LE( X0, output, 0 );
|
|
PUT_ULONG_LE( X1, output, 4 );
|
|
PUT_ULONG_LE( X2, output, 8 );
|
|
PUT_ULONG_LE( X3, output, 12 );
|
|
}
|
|
|
|
/*
|
|
* AES-CBC buffer encryption/decryption
|
|
*/
|
|
void aes_crypt_cbc( aes_context *ctx,
|
|
int mode,
|
|
int length,
|
|
unsigned char iv[16],
|
|
const unsigned char *input,
|
|
unsigned char *output )
|
|
{
|
|
int i;
|
|
unsigned char temp[16];
|
|
|
|
#if defined(XYSSL_PADLOCK_C) && defined(XYSSL_HAVE_X86)
|
|
if( padlock_supports( PADLOCK_ACE ) )
|
|
{
|
|
if( padlock_xcryptcbc( ctx, mode, length, iv, input, output ) == 0 )
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
if( mode == AES_DECRYPT )
|
|
{
|
|
while( length > 0 )
|
|
{
|
|
memcpy( temp, input, 16 );
|
|
aes_crypt_ecb( ctx, mode, input, output );
|
|
|
|
for( i = 0; i < 16; i++ )
|
|
output[i] = (unsigned char)( output[i] ^ iv[i] );
|
|
|
|
memcpy( iv, temp, 16 );
|
|
|
|
input += 16;
|
|
output += 16;
|
|
length -= 16;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
while( length > 0 )
|
|
{
|
|
for( i = 0; i < 16; i++ )
|
|
output[i] = (unsigned char)( input[i] ^ iv[i] );
|
|
|
|
aes_crypt_ecb( ctx, mode, output, output );
|
|
memcpy( iv, output, 16 );
|
|
|
|
input += 16;
|
|
output += 16;
|
|
length -= 16;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* AES-CFB buffer encryption/decryption
|
|
*/
|
|
void aes_crypt_cfb( aes_context *ctx,
|
|
int mode,
|
|
int length,
|
|
int *iv_off,
|
|
unsigned char iv[16],
|
|
const unsigned char *input,
|
|
unsigned char *output )
|
|
{
|
|
int c, n = *iv_off;
|
|
|
|
if( mode == AES_DECRYPT )
|
|
{
|
|
while( length-- )
|
|
{
|
|
if( n == 0 )
|
|
aes_crypt_ecb( ctx, AES_ENCRYPT, iv, iv );
|
|
|
|
c = *input++;
|
|
*output++ = (unsigned char)( c ^ iv[n] );
|
|
iv[n] = (unsigned char) c;
|
|
|
|
n = (n + 1) & 0x0F;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
while( length-- )
|
|
{
|
|
if( n == 0 )
|
|
aes_crypt_ecb( ctx, AES_ENCRYPT, iv, iv );
|
|
|
|
iv[n] = *output++ = (unsigned char)( iv[n] ^ *input++ );
|
|
|
|
n = (n + 1) & 0x0F;
|
|
}
|
|
}
|
|
|
|
*iv_off = n;
|
|
}
|