90 lines
2.8 KiB
C
Executable File
90 lines
2.8 KiB
C
Executable File
#include <stdlib.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <string.h>
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#include <nettle/nettle-meta.h>
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#include <nettle/aes.h>
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#include <nettle/ctr.h>
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#include "assertions.h"
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#include "conversions.h"
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#include "secu_defs.h"
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#include "snow3g.h"
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// #define SECU_DEBUG
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int nas_stream_encrypt_eea1(nas_stream_cipher_t *stream_cipher, uint8_t **out)
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{
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snow_3g_context_t snow_3g_context;
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int n ;
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int i = 0;
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uint32_t zero_bit = 0;
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uint32_t byte_length;
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uint32_t *KS;
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uint32_t K[4],IV[4];
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DevAssert(stream_cipher != NULL);
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DevAssert(stream_cipher->key != NULL);
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DevAssert(stream_cipher->key_length == 16);
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DevAssert(out != NULL);
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n = ( stream_cipher->blength + 31 ) / 32;
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zero_bit = stream_cipher->blength & 0x7;
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byte_length = stream_cipher->blength >> 3;
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memset(&snow_3g_context, 0, sizeof(snow_3g_context));
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/*Initialisation*/
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/* Load the confidentiality key for SNOW 3G initialization as in section
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3.4. */
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memcpy(K+3,stream_cipher->key+0,4); /*K[3] = key[0]; we assume
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K[3]=key[0]||key[1]||...||key[31] , with key[0] the
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* most important bit of key*/
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memcpy(K+2,stream_cipher->key+4,4); /*K[2] = key[1];*/
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memcpy(K+1,stream_cipher->key+8,4); /*K[1] = key[2];*/
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memcpy(K+0,stream_cipher->key+12,4); /*K[0] = key[3]; we assume
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K[0]=key[96]||key[97]||...||key[127] , with key[127] the
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* least important bit of key*/
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K[3] = hton_int32(K[3]);
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K[2] = hton_int32(K[2]);
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K[1] = hton_int32(K[1]);
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K[0] = hton_int32(K[0]);
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/* Prepare the initialization vector (IV) for SNOW 3G initialization as in
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section 3.4. */
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IV[3] = stream_cipher->count;
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IV[2] = ((((uint32_t)stream_cipher->bearer) << 3) | ((((uint32_t)stream_cipher->direction) & 0x1) << 2)) << 24;
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IV[1] = IV[3];
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IV[0] = IV[2];
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/* Run SNOW 3G algorithm to generate sequence of key stream bits KS*/
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snow3g_initialize(K, IV, &snow_3g_context);
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KS = (uint32_t *)malloc(4*n);
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snow3g_generate_key_stream(n,(uint32_t*)KS, &snow_3g_context);
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if (zero_bit > 0) {
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KS[n - 1] = KS[n - 1] & (uint32_t)(0xFFFFFFFF << (8 - zero_bit));
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}
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for (i=0;i<n;i++) {
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KS[i] = hton_int32(KS[i]);
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}
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/* Exclusive-OR the input data with keystream to generate the output bit
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stream */
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for (i=0;i<n*4;i++) {
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stream_cipher->message[i] ^= *(((uint8_t*)KS)+i);
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}
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if (zero_bit > 0) {
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int ceil_index = (stream_cipher->blength+7) >> 3;
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printf ("changing stream_cipher->message[%u]: %08X to %08X remove %d bits\n",
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ceil_index - 1,
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stream_cipher->message[ceil_index - 1],
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stream_cipher->message[ceil_index - 1] & (uint8_t)(0xFF << (8 - zero_bit)),
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8 - zero_bit);
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stream_cipher->message[ceil_index - 1] = stream_cipher->message[ceil_index - 1] & (uint8_t)(0xFF << (8 - zero_bit));
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}
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free(KS);
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*out = stream_cipher->message;
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return 0;
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}
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