18d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt/* 28d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * AES (Rijndael) cipher - decrypt 38d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * 48d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * Modifications to public domain implementation: 58d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * - support only 128-bit keys 68d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * - cleanup 78d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * - use C pre-processor to make it easier to change S table access 88d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * - added option (AES_SMALL_TABLES) for reducing code size by about 8 kB at 98d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * cost of reduced throughput (quite small difference on Pentium 4, 108d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * 10-25% when using -O1 or -O2 optimization) 118d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * 128d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi> 138d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * 14c5ec7f57ead87efa365800228aa0b09a12d9e6c4Dmitry Shmidt * This software may be distributed under the terms of the BSD license. 15c5ec7f57ead87efa365800228aa0b09a12d9e6c4Dmitry Shmidt * See README for more details. 168d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt */ 178d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 188d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#include "includes.h" 198d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 208d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#include "common.h" 218d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#include "crypto.h" 228d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#include "aes_i.h" 238d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 248d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt/** 258d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * Expand the cipher key into the decryption key schedule. 268d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * 278d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * @return the number of rounds for the given cipher key size. 288d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt */ 291f69aa52ea2e0a73ac502565df8c666ee49cab6aDmitry Shmidtstatic void rijndaelKeySetupDec(u32 rk[/*44*/], const u8 cipherKey[]) 308d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt{ 318d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt int Nr = 10, i, j; 328d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt u32 temp; 338d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 348d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt /* expand the cipher key: */ 358d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt rijndaelKeySetupEnc(rk, cipherKey); 368d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt /* invert the order of the round keys: */ 378d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt for (i = 0, j = 4*Nr; i < j; i += 4, j -= 4) { 388d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt temp = rk[i ]; rk[i ] = rk[j ]; rk[j ] = temp; 398d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt temp = rk[i + 1]; rk[i + 1] = rk[j + 1]; rk[j + 1] = temp; 408d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt temp = rk[i + 2]; rk[i + 2] = rk[j + 2]; rk[j + 2] = temp; 418d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt temp = rk[i + 3]; rk[i + 3] = rk[j + 3]; rk[j + 3] = temp; 428d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt } 438d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt /* apply the inverse MixColumn transform to all round keys but the 448d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * first and the last: */ 458d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt for (i = 1; i < Nr; i++) { 468d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt rk += 4; 478d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt for (j = 0; j < 4; j++) { 488d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt rk[j] = TD0_(TE4((rk[j] >> 24) )) ^ 498d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt TD1_(TE4((rk[j] >> 16) & 0xff)) ^ 508d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt TD2_(TE4((rk[j] >> 8) & 0xff)) ^ 518d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt TD3_(TE4((rk[j] ) & 0xff)); 528d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt } 538d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt } 548d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt} 558d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 568d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidtvoid * aes_decrypt_init(const u8 *key, size_t len) 578d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt{ 588d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt u32 *rk; 598d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt if (len != 16) 608d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt return NULL; 618d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt rk = os_malloc(AES_PRIV_SIZE); 628d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt if (rk == NULL) 638d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt return NULL; 648d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt rijndaelKeySetupDec(rk, key); 658d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt return rk; 668d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt} 678d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 688d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidtstatic void rijndaelDecrypt(const u32 rk[/*44*/], const u8 ct[16], u8 pt[16]) 698d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt{ 708d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt u32 s0, s1, s2, s3, t0, t1, t2, t3; 718d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt const int Nr = 10; 728d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#ifndef FULL_UNROLL 738d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt int r; 748d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#endif /* ?FULL_UNROLL */ 758d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 768d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt /* 778d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * map byte array block to cipher state 788d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * and add initial round key: 798d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt */ 808d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt s0 = GETU32(ct ) ^ rk[0]; 818d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt s1 = GETU32(ct + 4) ^ rk[1]; 828d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt s2 = GETU32(ct + 8) ^ rk[2]; 838d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt s3 = GETU32(ct + 12) ^ rk[3]; 848d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 858d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#define ROUND(i,d,s) \ 868d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidtd##0 = TD0(s##0) ^ TD1(s##3) ^ TD2(s##2) ^ TD3(s##1) ^ rk[4 * i]; \ 878d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidtd##1 = TD0(s##1) ^ TD1(s##0) ^ TD2(s##3) ^ TD3(s##2) ^ rk[4 * i + 1]; \ 888d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidtd##2 = TD0(s##2) ^ TD1(s##1) ^ TD2(s##0) ^ TD3(s##3) ^ rk[4 * i + 2]; \ 898d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidtd##3 = TD0(s##3) ^ TD1(s##2) ^ TD2(s##1) ^ TD3(s##0) ^ rk[4 * i + 3] 908d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 918d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#ifdef FULL_UNROLL 928d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 938d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(1,t,s); 948d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(2,s,t); 958d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(3,t,s); 968d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(4,s,t); 978d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(5,t,s); 988d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(6,s,t); 998d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(7,t,s); 1008d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(8,s,t); 1018d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(9,t,s); 1028d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 1038d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt rk += Nr << 2; 1048d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 1058d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#else /* !FULL_UNROLL */ 1068d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 1078d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt /* Nr - 1 full rounds: */ 1088d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt r = Nr >> 1; 1098d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt for (;;) { 1108d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(1,t,s); 1118d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt rk += 8; 1128d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt if (--r == 0) 1138d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt break; 1148d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt ROUND(0,s,t); 1158d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt } 1168d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 1178d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#endif /* ?FULL_UNROLL */ 1188d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 1198d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt#undef ROUND 1208d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 1218d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt /* 1228d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * apply last round and 1238d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt * map cipher state to byte array block: 1248d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt */ 1258d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt s0 = TD41(t0) ^ TD42(t3) ^ TD43(t2) ^ TD44(t1) ^ rk[0]; 1268d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt PUTU32(pt , s0); 1278d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt s1 = TD41(t1) ^ TD42(t0) ^ TD43(t3) ^ TD44(t2) ^ rk[1]; 1288d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt PUTU32(pt + 4, s1); 1298d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt s2 = TD41(t2) ^ TD42(t1) ^ TD43(t0) ^ TD44(t3) ^ rk[2]; 1308d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt PUTU32(pt + 8, s2); 1318d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt s3 = TD41(t3) ^ TD42(t2) ^ TD43(t1) ^ TD44(t0) ^ rk[3]; 1328d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt PUTU32(pt + 12, s3); 1338d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt} 1348d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 1358d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidtvoid aes_decrypt(void *ctx, const u8 *crypt, u8 *plain) 1368d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt{ 1378d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt rijndaelDecrypt(ctx, crypt, plain); 1388d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt} 1398d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 1408d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt 1418d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidtvoid aes_decrypt_deinit(void *ctx) 1428d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt{ 1438d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt os_memset(ctx, 0, AES_PRIV_SIZE); 1448d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt os_free(ctx); 1458d520ff1dc2da35cdca849e982051b86468016d8Dmitry Shmidt} 146