/******************************************************************************* OpenAirInterface Copyright(c) 1999 - 2014 Eurecom OpenAirInterface is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. OpenAirInterface is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenAirInterface.The full GNU General Public License is included in this distribution in the file called "COPYING". If not, see <http://www.gnu.org/licenses/>. Contact Information OpenAirInterface Admin: openair_admin@eurecom.fr OpenAirInterface Tech : openair_tech@eurecom.fr OpenAirInterface Dev : openair4g-devel@eurecom.fr Address : Eurecom, Compus SophiaTech 450, route des chappes, 06451 Biot, France. *******************************************************************************/ #include <stdlib.h> #include <stdio.h> #include <stdint.h> #include <string.h> #include <nettle/nettle-meta.h> #include <nettle/aes.h> #include <nettle/ctr.h> #include "assertions.h" #include "conversions.h" #include "secu_defs.h" #include "snow3g.h" // #define SECU_DEBUG int nas_stream_encrypt_eea1(nas_stream_cipher_t *stream_cipher, uint8_t *out) { snow_3g_context_t snow_3g_context; int n ; int i = 0; uint32_t zero_bit = 0; uint32_t byte_length; uint32_t *KS; uint32_t K[4],IV[4]; DevAssert(stream_cipher != NULL); DevAssert(stream_cipher->key != NULL); DevAssert(stream_cipher->key_length == 16); DevAssert(out != NULL); n = ( stream_cipher->blength + 31 ) / 32; zero_bit = stream_cipher->blength & 0x7; byte_length = stream_cipher->blength >> 3; memset(&snow_3g_context, 0, sizeof(snow_3g_context)); /*Initialisation*/ /* Load the confidentiality key for SNOW 3G initialization as in section 3.4. */ memcpy(K+3,stream_cipher->key+0,4); /*K[3] = key[0]; we assume K[3]=key[0]||key[1]||...||key[31] , with key[0] the * most important bit of key*/ memcpy(K+2,stream_cipher->key+4,4); /*K[2] = key[1];*/ memcpy(K+1,stream_cipher->key+8,4); /*K[1] = key[2];*/ memcpy(K+0,stream_cipher->key+12,4); /*K[0] = key[3]; we assume K[0]=key[96]||key[97]||...||key[127] , with key[127] the * least important bit of key*/ K[3] = hton_int32(K[3]); K[2] = hton_int32(K[2]); K[1] = hton_int32(K[1]); K[0] = hton_int32(K[0]); /* Prepare the initialization vector (IV) for SNOW 3G initialization as in section 3.4. */ IV[3] = stream_cipher->count; IV[2] = ((((uint32_t)stream_cipher->bearer) << 3) | ((((uint32_t)stream_cipher->direction) & 0x1) << 2)) << 24; IV[1] = IV[3]; IV[0] = IV[2]; /* Run SNOW 3G algorithm to generate sequence of key stream bits KS*/ snow3g_initialize(K, IV, &snow_3g_context); KS = (uint32_t *)malloc(4*n); snow3g_generate_key_stream(n,(uint32_t*)KS, &snow_3g_context); if (zero_bit > 0) { KS[n - 1] = KS[n - 1] & (uint32_t)(0xFFFFFFFF << (8 - zero_bit)); } for (i=0;i<n;i++) { KS[i] = hton_int32(KS[i]); } /* Exclusive-OR the input data with keystream to generate the output bit stream */ for (i=0;i<n*4;i++) { stream_cipher->message[i] ^= *(((uint8_t*)KS)+i); } int ceil_index = 0; if (zero_bit > 0) { ceil_index = (stream_cipher->blength+7) >> 3; stream_cipher->message[ceil_index - 1] = stream_cipher->message[ceil_index - 1] & (uint8_t)(0xFF << (8 - zero_bit)); } free(KS); memcpy(out, stream_cipher->message, n*4); if (zero_bit > 0) { out[ceil_index - 1] = stream_cipher->message[ceil_index - 1]; } return 0; }