xtea.c

00001 /*
00002  *  An 32-bit implementation of the XTEA algorithm
00003  *
00004  *  Copyright (C) 2006-2014, ARM Limited, All Rights Reserved
00005  *
00006  *  This file is part of mbed TLS (https://tls.mbed.org)
00007  *
00008  *  This program is free software; you can redistribute it and/or modify
00009  *  it under the terms of the GNU General Public License as published by
00010  *  the Free Software Foundation; either version 2 of the License, or
00011  *  (at your option) any later version.
00012  *
00013  *  This program is distributed in the hope that it will be useful,
00014  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016  *  GNU General Public License for more details.
00017  *
00018  *  You should have received a copy of the GNU General Public License along
00019  *  with this program; if not, write to the Free Software Foundation, Inc.,
00020  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00021  */
00022 
00023 #if !defined(POLARSSL_CONFIG_FILE)
00024 #include "polarssl/config.h"
00025 #else
00026 #include POLARSSL_CONFIG_FILE
00027 #endif
00028 
00029 #if defined(POLARSSL_XTEA_C)
00030 
00031 #include "polarssl/xtea.h"
00032 
00033 #include <string.h>
00034 
00035 #if defined(POLARSSL_SELF_TEST)
00036 #if defined(POLARSSL_PLATFORM_C)
00037 #include "polarssl/platform.h"
00038 #else
00039 #include <stdio.h>
00040 #define polarssl_printf printf
00041 #endif /* POLARSSL_PLATFORM_C */
00042 #endif /* POLARSSL_SELF_TEST */
00043 
00044 #if !defined(POLARSSL_XTEA_ALT)
00045 
00046 /* Implementation that should never be optimized out by the compiler */
00047 static void polarssl_zeroize( void *v, size_t n ) {
00048     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
00049 }
00050 
00051 /*
00052  * 32-bit integer manipulation macros (big endian)
00053  */
00054 #ifndef GET_UINT32_BE
00055 #define GET_UINT32_BE(n,b,i)                            \
00056 {                                                       \
00057     (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
00058         | ( (uint32_t) (b)[(i) + 1] << 16 )             \
00059         | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
00060         | ( (uint32_t) (b)[(i) + 3]       );            \
00061 }
00062 #endif
00063 
00064 #ifndef PUT_UINT32_BE
00065 #define PUT_UINT32_BE(n,b,i)                            \
00066 {                                                       \
00067     (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
00068     (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
00069     (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
00070     (b)[(i) + 3] = (unsigned char) ( (n)       );       \
00071 }
00072 #endif
00073 
00074 void xtea_init( xtea_context *ctx )
00075 {
00076     memset( ctx, 0, sizeof( xtea_context ) );
00077 }
00078 
00079 void xtea_free( xtea_context *ctx )
00080 {
00081     if( ctx == NULL )
00082         return;
00083 
00084     polarssl_zeroize( ctx, sizeof( xtea_context ) );
00085 }
00086 
00087 /*
00088  * XTEA key schedule
00089  */
00090 void xtea_setup( xtea_context *ctx, const unsigned char key[16] )
00091 {
00092     int i;
00093 
00094     memset( ctx, 0, sizeof(xtea_context) );
00095 
00096     for( i = 0; i < 4; i++ )
00097     {
00098         GET_UINT32_BE( ctx->k [i], key, i << 2 );
00099     }
00100 }
00101 
00102 /*
00103  * XTEA encrypt function
00104  */
00105 int xtea_crypt_ecb( xtea_context *ctx, int mode,
00106                     const unsigned char input[8], unsigned char output[8])
00107 {
00108     uint32_t *k, v0, v1, i;
00109 
00110     k = ctx->k ;
00111 
00112     GET_UINT32_BE( v0, input, 0 );
00113     GET_UINT32_BE( v1, input, 4 );
00114 
00115     if( mode == XTEA_ENCRYPT )
00116     {
00117         uint32_t sum = 0, delta = 0x9E3779B9;
00118 
00119         for( i = 0; i < 32; i++ )
00120         {
00121             v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + k[sum & 3]);
00122             sum += delta;
00123             v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + k[(sum>>11) & 3]);
00124         }
00125     }
00126     else /* XTEA_DECRYPT */
00127     {
00128         uint32_t delta = 0x9E3779B9, sum = delta * 32;
00129 
00130         for( i = 0; i < 32; i++ )
00131         {
00132             v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + k[(sum>>11) & 3]);
00133             sum -= delta;
00134             v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + k[sum & 3]);
00135         }
00136     }
00137 
00138     PUT_UINT32_BE( v0, output, 0 );
00139     PUT_UINT32_BE( v1, output, 4 );
00140 
00141     return( 0 );
00142 }
00143 
00144 #if defined(POLARSSL_CIPHER_MODE_CBC)
00145 /*
00146  * XTEA-CBC buffer encryption/decryption
00147  */
00148 int xtea_crypt_cbc( xtea_context *ctx, int mode, size_t length,
00149                     unsigned char iv[8], const unsigned char *input,
00150                     unsigned char *output)
00151 {
00152     int i;
00153     unsigned char temp[8];
00154 
00155     if( length % 8 )
00156         return( POLARSSL_ERR_XTEA_INVALID_INPUT_LENGTH );
00157 
00158     if( mode == XTEA_DECRYPT )
00159     {
00160         while( length > 0 )
00161         {
00162             memcpy( temp, input, 8 );
00163             xtea_crypt_ecb( ctx, mode, input, output );
00164 
00165             for( i = 0; i < 8; i++ )
00166                 output[i] = (unsigned char)( output[i] ^ iv[i] );
00167 
00168             memcpy( iv, temp, 8 );
00169 
00170             input  += 8;
00171             output += 8;
00172             length -= 8;
00173         }
00174     }
00175     else
00176     {
00177         while( length > 0 )
00178         {
00179             for( i = 0; i < 8; i++ )
00180                 output[i] = (unsigned char)( input[i] ^ iv[i] );
00181 
00182             xtea_crypt_ecb( ctx, mode, output, output );
00183             memcpy( iv, output, 8 );
00184 
00185             input  += 8;
00186             output += 8;
00187             length -= 8;
00188         }
00189     }
00190 
00191     return( 0 );
00192 }
00193 #endif /* POLARSSL_CIPHER_MODE_CBC */
00194 #endif /* !POLARSSL_XTEA_ALT */
00195 
00196 #if defined(POLARSSL_SELF_TEST)
00197 
00198 /*
00199  * XTEA tests vectors (non-official)
00200  */
00201 
00202 static const unsigned char xtea_test_key[6][16] =
00203 {
00204    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
00205      0x0c, 0x0d, 0x0e, 0x0f },
00206    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
00207      0x0c, 0x0d, 0x0e, 0x0f },
00208    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
00209      0x0c, 0x0d, 0x0e, 0x0f },
00210    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00211      0x00, 0x00, 0x00, 0x00 },
00212    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00213      0x00, 0x00, 0x00, 0x00 },
00214    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00215      0x00, 0x00, 0x00, 0x00 }
00216 };
00217 
00218 static const unsigned char xtea_test_pt[6][8] =
00219 {
00220     { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
00221     { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
00222     { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
00223     { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
00224     { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
00225     { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
00226 };
00227 
00228 static const unsigned char xtea_test_ct[6][8] =
00229 {
00230     { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
00231     { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
00232     { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
00233     { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
00234     { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
00235     { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
00236 };
00237 
00238 /*
00239  * Checkup routine
00240  */
00241 int xtea_self_test( int verbose )
00242 {
00243     int i, ret = 0;
00244     unsigned char buf[8];
00245     xtea_context ctx;
00246 
00247     xtea_init( &ctx );
00248     for( i = 0; i < 6; i++ )
00249     {
00250         if( verbose != 0 )
00251             polarssl_printf( "  XTEA test #%d: ", i + 1 );
00252 
00253         memcpy( buf, xtea_test_pt[i], 8 );
00254 
00255         xtea_setup( &ctx, xtea_test_key[i] );
00256         xtea_crypt_ecb( &ctx, XTEA_ENCRYPT, buf, buf );
00257 
00258         if( memcmp( buf, xtea_test_ct[i], 8 ) != 0 )
00259         {
00260             if( verbose != 0 )
00261                 polarssl_printf( "failed\n" );
00262 
00263             ret = 1;
00264             goto exit;
00265         }
00266 
00267         if( verbose != 0 )
00268             polarssl_printf( "passed\n" );
00269     }
00270 
00271     if( verbose != 0 )
00272         polarssl_printf( "\n" );
00273 
00274 exit:
00275     xtea_free( &ctx );
00276 
00277     return( ret );
00278 }
00279 
00280 #endif /* POLARSSL_SELF_TEST */
00281 
00282 #endif /* POLARSSL_XTEA_C */
00283