/* MODULE -- encryption function Copyright (C) Alberto Ornaghi $Id: encryption_tkip.c 2910 2010-09-23 09:40:28Z alor $ */ #include #include #include #include #include #include /* globals */ /* Note: copied from FreeBSD source code, RELENG 6, sys/net80211/ieee80211_crypto_tkip.c, 471 */ static const u_int16 Sbox[256] = { 0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154, 0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A, 0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B, 0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B, 0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F, 0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F, 0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5, 0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F, 0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB, 0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397, 0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED, 0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A, 0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194, 0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3, 0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104, 0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D, 0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39, 0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695, 0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83, 0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76, 0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4, 0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B, 0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0, 0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018, 0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751, 0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85, 0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12, 0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9, 0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7, 0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A, 0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8, 0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A, }; #define TKIP_TA_OFFSET 10 #define TKIP_PHASE1_LOOP_COUNT 8 #define TKIP_TTAK_LEN 6 #define TKIP_WEP_128_KEY_LEN 16 /* 128 bit */ #define to_int16(hi, lo) ((u_int16)((lo) | (((u_int16)(hi)) << 8))) #define RotR1(val) ((u_int16)(((val) >> 1) | ((val) << 15))) #define Lo8(val) ((u_int8)((val) & 0xff)) #define Hi8(val) ((u_int8)((val) >> 8)) #define Lo16(val) ((u_int16)((val) & 0xffff)) #define Hi16(val) ((u_int16)((val) >> 16)) #define _S_(v) ((u_int16)(Sbox[Lo8(v)] ^ ((Sbox[Hi8(v)] << 8) | (Sbox[Hi8(v)] >> 8)))) #define pletohs(p) ((u_int16) \ ((u_int16)*((const u_int8 *)(p)+1)<<8| \ (u_int16)*((const u_int8 *)(p)+0)<<0)) #define Mk16_le(v) ((u_int16)pletohs(v)) /* protos */ int wpa_tkip_decrypt(u_char *mac, u_char *data, size_t len, struct wpa_sa sa); static inline void get_TSC(u_int32 *TSC32, u_int16 *TSC16, u_char *data); static inline void tkip_mixing_phase1(u_int16 *TTAK, u_int8 *TK, u_int8 *TA, u_int32 TSC32); static inline void tkip_mixing_phase2(u_int8 *WEP, u_int8 *TK, u_int16 *TTAK, u_int16 TSC16); static int tkip_decrypt(u_char *decbuf, size_t len, u_int8 *wep_seed); /*******************************************/ /* * IEEE-802.11i-2004 8.3.2.1 */ int wpa_tkip_decrypt(u_char *mac, u_char *data, size_t len, struct wpa_sa sa) { u_int32 TSC32; /* TKIP Sequence Counter ( 2, 3, 4, 5 ) */ u_int16 TSC16; /* TKIP Sequence Counter ( 1, 0 ) */ u_int16 TTAK[TKIP_TTAK_LEN]; u_int8 wep_seed[TKIP_WEP_128_KEY_LEN]; u_char decbuf[len]; /* get the TKIP Sequence Counter */ get_TSC(&TSC32, &TSC16, data); memset(TTAK, 0, sizeof(TTAK)); /* create the seed for the WEP decryption */ tkip_mixing_phase1(TTAK, sa.decryption_key, mac + TKIP_TA_OFFSET, TSC32); tkip_mixing_phase2(wep_seed, sa.decryption_key, TTAK, TSC16); /* copy the encrypted data to the decryption buffer (skipping the wpa parameters) */ memcpy(decbuf, data + sizeof(struct wpa_header), len); /* decrypt the packet */ if (tkip_decrypt(decbuf, len - WEP_CRC_LEN, wep_seed) != 0) { DEBUG_MSG(D_VERBOSE, "WPA (TKIP) decryption failed, packet was skipped"); return -ENOTHANDLED; } /* * copy the decrypted packet over the original one * overwriting the wpa header. this way the packet is * identical to a non-WPA one. */ memcpy(data, decbuf, len); /* * wipe out the remaining bytes at the end of the packets * we have moved the data over the wpa header and the WEP crc was left * at the end of the packet. */ memset(data + len - WEP_CRC_LEN, 0, WEP_CRC_LEN); return ESUCCESS; } /* * IEEE-802.11i-2004 8.3.2.2 * * ------------------------------------------------ * |TSC1|WEPSeed|TSC0|Reserved|TSC2|TSC3|TSC4|TSC5| * ------------------------------------------------ */ static inline void get_TSC(u_int32 *TSC32, u_int16 *TSC16, u_char *data) { *TSC16 = to_int16(data[0], data[2]); *TSC32 = ( (u_int32)(data[7]) << 24 ) | ( (u_int32)(data[6]) << 16 ) | ( (u_int32)(data[5]) << 8 ) | ( (u_int32)(data[4]) ); } /* * IEEE-802.11i-2004 8.3.2.5 */ static inline void tkip_mixing_phase1(u_int16 *TTAK, u_int8 *TK, u_int8 *TA, u_int32 TSC32) { u_int16 i, j; /* Initialize the 80-bit TTAK from TSC (TSC32) and TA[0..5] */ TTAK[0] = Lo16(TSC32); TTAK[1] = Hi16(TSC32); TTAK[2] = to_int16(TA[1], TA[0]); TTAK[3] = to_int16(TA[3], TA[2]); TTAK[4] = to_int16(TA[5], TA[4]); for (i = 0; i < TKIP_PHASE1_LOOP_COUNT; i++) { j = (u_int16)(2 * (i & 1)); TTAK[0] = (u_int16)(TTAK[0] + _S_((u_int16)(TTAK[4] ^ to_int16(TK[1 + j], TK[0 + j])))); TTAK[1] = (u_int16)(TTAK[1] + _S_((u_int16)(TTAK[0] ^ to_int16(TK[5 + j], TK[4 + j])))); TTAK[2] = (u_int16)(TTAK[2] + _S_((u_int16)(TTAK[1] ^ to_int16(TK[9 + j], TK[8 + j])))); TTAK[3] = (u_int16)(TTAK[3] + _S_((u_int16)(TTAK[2] ^ to_int16(TK[13 + j], TK[12 + j])))); TTAK[4] = (u_int16)(TTAK[4] + _S_((u_int16)(TTAK[3] ^ to_int16(TK[1 + j], TK[0 + j]))) + i); } } static inline void tkip_mixing_phase2(u_int8 *WEP, u_int8 *TK, u_int16 *TTAK, u_int16 TSC16) { int i; TTAK[5] = (u_int16)(TTAK[4] + TSC16); /* Step 2 - 96-bit bijective mixing using S-box */ TTAK[0] = (u_int16)(TTAK[0] + _S_((u_int16)(TTAK[5] ^ Mk16_le(&TK[0])))); TTAK[1] = (u_int16)(TTAK[1] + _S_((u_int16)(TTAK[0] ^ Mk16_le(&TK[2])))); TTAK[2] = (u_int16)(TTAK[2] + _S_((u_int16)(TTAK[1] ^ Mk16_le(&TK[4])))); TTAK[3] = (u_int16)(TTAK[3] + _S_((u_int16)(TTAK[2] ^ Mk16_le(&TK[6])))); TTAK[4] = (u_int16)(TTAK[4] + _S_((u_int16)(TTAK[3] ^ Mk16_le(&TK[8])))); TTAK[5] = (u_int16)(TTAK[5] + _S_((u_int16)(TTAK[4] ^ Mk16_le(&TK[10])))); TTAK[0] = (u_int16)(TTAK[0] + RotR1((u_int16)(TTAK[5] ^ Mk16_le(&TK[12])))); TTAK[1] = (u_int16)(TTAK[1] + RotR1((u_int16)(TTAK[0] ^ Mk16_le(&TK[14])))); TTAK[2] = (u_int16)(TTAK[2] + RotR1(TTAK[1])); TTAK[3] = (u_int16)(TTAK[3] + RotR1(TTAK[2])); TTAK[4] = (u_int16)(TTAK[4] + RotR1(TTAK[3])); TTAK[5] = (u_int16)(TTAK[5] + RotR1(TTAK[4])); /* * Step 3 - bring in last of TK bits, assign 24-bit WEP IV value * WEP[0..2] is transmitted as WEP IV */ WEP[0] = Hi8(TSC16); WEP[1] = (u_int8)((Hi8(TSC16) | 0x20) & 0x7F); WEP[2] = Lo8(TSC16); WEP[3] = Lo8((u_int16)((TTAK[5] ^ Mk16_le(&TK[0])) >> 1)); for (i = 0; i < 6; i++) { WEP[4 + (2 * i)] = Lo8(TTAK[i]); WEP[5 + (2 * i)] = Hi8(TTAK[i]); } } /* * decryption of tkip is like WEP, RC4 algorithm */ static int tkip_decrypt(u_char *decbuf, size_t len, u_int8 *wep_seed) { RC4_KEY key; /* initialize the RC4 key */ RC4_set_key(&key, TKIP_WEP_128_KEY_LEN, wep_seed); /* decrypt the frame (len + 4 byte of crc) */ RC4(&key, len + WEP_CRC_LEN, decbuf, decbuf); /* * check if the decryption was successful: * at the end of the packet there is a CRC check */ if (CRC_checksum(decbuf, len + WEP_CRC_LEN, CRC_INIT) != CRC_RESULT) { DEBUG_MSG(D_VERBOSE, "WEP: invalid key, the packet was skipped\n"); return -ENOTHANDLED; } return ESUCCESS; } /* EOF */ // vim:ts=3:expandtab .