5G/4G128-EIA1与128-NIA1算法详解

Posted 2021-09-09 从善若水

文章目录

• 【5G/4G】128-EIA1与128-NIA1算法详解

本人就职于国际知名终端厂商，负责modem芯片研发。
在5G早期负责终端数据业务层、核心网相关的开发工作，目前牵头6G算力网络技术标准研究。


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【5G/4G】128-EIA1与128-NIA1算法详解

secu_defs.h

typedef struct {
  uint8_t *key;
  uint32_t key_length;
  uint32_t count;
  uint8_t  bearer;
  uint8_t  direction;
  uint8_t  *message;
  /* length in bits */
  uint32_t  blength;
} stream_cipher_t;

conversions.h

/* Endianness conversions for 16 and 32 bits integers from host to network order */
#if (BYTE_ORDER == LITTLE_ENDIAN)
# define hton_int32(x)   \\
    (((x & 0x000000FF) << 24) | ((x & 0x0000FF00) << 8) |  \\
    ((x & 0x00FF0000) >> 8) | ((x & 0xFF000000) >> 24))

# define hton_int16(x)   \\
    (((x & 0x00FF) << 8) | ((x & 0xFF00) >> 8)

# define ntoh_int32_buf(bUF)        \\
    ((*(bUF)) << 24) | ((*((bUF) + 1)) << 16) | ((*((bUF) + 2)) << 8)   \\
  | (*((bUF) + 3))
#else
# define hton_int32(x) (x)
# define hton_int16(x) (x)
#endif

nia1_eia1_stream.c

#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <math.h> // double ceil(double x);

#include "secu_defs.h"
#include "conversions.h"
#include "snow3g.h"

#define SECU_DEBUG

uint64_t MUL64x(uint64_t V, uint64_t c);
uint64_t MUL64xPOW(uint64_t V, uint32_t i, uint64_t c);
uint64_t MUL64(uint64_t V, uint64_t P, uint64_t c);
int      nia1_eia1(stream_cipher_t *stream_cipher, uint8_t out[4]);


// see spec 3GPP Confidentiality and Integrity Algorithms UEA2&UIA2. Document 1: UEA2 and UIA2 Specification. Version 1.1

/* MUL64x.
 * Input V: a 64-bit input.
 * Input c: a 64-bit input.
 * Output : a 64-bit output.
 * A 64-bit memory is allocated which is to be freed by the calling
 * function.
 * See section 4.3.2 for details.
 */
uint64_t MUL64x(uint64_t V, uint64_t c)
{
  if ( V & 0x8000000000000000 )
    return (V << 1) ^ c;
  else
    return V << 1;
}
/* MUL64xPOW.
 * Input V: a 64-bit input.
 * Input i: a positive integer.
 * Input c: a 64-bit input.
 * Output : a 64-bit output.
 * A 64-bit memory is allocated which is to be freed by the calling
function.
 * See section 4.3.3 for details.
 */
uint64_t MUL64xPOW(uint64_t V, uint32_t i, uint64_t c)
{
  if ( i == 0)
    return V;
  else
    return MUL64x( MUL64xPOW(V,i-1,c) , c);
}
/* MUL64.
 * Input V: a 64-bit input.
 * Input P: a 64-bit input.
 * Input c: a 64-bit input.
 * Output : a 64-bit output.
 * A 64-bit memory is allocated which is to be freed by the calling
 * function.
 * See section 4.3.4 for details.
 */
uint64_t MUL64(uint64_t V, uint64_t P, uint64_t c)
{
  uint64_t result = 0;
  int i = 0;

  for ( i=0; i<64; i++) {
    if( ( P>>i ) & 0x1 )
      result ^= MUL64xPOW(V,i,c);
  }

  return result;
}

/* mask32bit.
* Input n: an integer in 1-32.
* Output : a 32 bit mask.
* Prepares a 32 bit mask with required number of 1 bits on the MSB side.
*/
uint32_t mask32bit(int n)
{
  uint32_t mask=0x0;

  if ( n%32 == 0 )
    return 0xffffffff;

  while (n--)
    mask = (mask>>1) ^ 0x80000000;

  return mask;
}


/*!
 * @brief Create integrity cmac t for a given message.
 * @param[in] stream_cipher Structure containing various variables to setup encoding
 * @param[out] out For EIA1 the output string is 32 bits long
 */
int nia1_eia1(stream_cipher_t *stream_cipher, uint8_t out[4])
{
  snow_3g_context_t snow_3g_context;
  uint32_t        K[4],IV[4], z[5];
  int             i=0,D;
  uint32_t        MAC_I = 0;
  uint64_t        EVAL;
  uint64_t        V;
  uint64_t        P;
  uint64_t        Q;
  uint64_t        c;
  uint64_t        M_D_2;
  int             rem_bits;
  uint32_t        mask = 0;
  uint32_t       *message;

  message = (uint32_t*)stream_cipher->message; /* To operate 32 bit message internally. */
  /* Load the Integrity Key for SNOW3G initialization as in section 4.4. */
  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 SNOW3G initialization as in
    section 4.4. */
  IV[3] = (uint32_t)stream_cipher->count;
  IV[2] = ((((uint32_t)stream_cipher->bearer) & 0x0000001F) << 27);
  IV[1] = (uint32_t)(stream_cipher->count) ^ ( (uint32_t)(stream_cipher->direction) << 31 ) ;
  IV[0] = ((((uint32_t)stream_cipher->bearer) & 0x0000001F) << 27) ^ ((uint32_t)(stream_cipher->direction & 0x00000001) << 15);

  z[0] = z[1] = z[2] = z[3] = z[4] = 0;
  /* Run SNOW 3G to produce 5 keystream words z_1, z_2, z_3, z_4 and z_5. */
  snow3g_initialize(K, IV, &snow_3g_context);
  snow3g_generate_key_stream(5, z, &snow_3g_context);

  P = ((uint64_t)z[0] << 32) | (uint64_t)z[1];
  Q = ((uint64_t)z[2] << 32) | (uint64_t)z[3];

  /* Calculation */
  D = ceil( stream_cipher->blength / 64.0 ) + 1;
  EVAL = 0;
  c = 0x1b;

  /* for 0 <= i <= D-3 */
  for (i=0; i<D-2; i++) {
    V = EVAL ^ ( (uint64_t)hton_int32(message[2*i]) << 32 | (uint64_t)hton_int32(message[2*i+1]) );
    EVAL = MUL64(V,P,c);
  }

  /* for D-2 */
  rem_bits = stream_cipher->blength % 64;

  if (rem_bits == 0)
    rem_bits = 64;

  mask = mask32bit(rem_bits%32);

  if (rem_bits > 32) {
    M_D_2 = ( (uint64_t) hton_int32(message[2*(D-2)]) << 32 ) |
            (uint64_t) (hton_int32(message[2*(D-2)+1]) &  mask);
  } else {
    M_D_2 = ( (uint64_t) hton_int32(message[2*(D-2)]) & mask) << 32 ;
  }

  V = EVAL ^ M_D_2;
  EVAL = MUL64(V,P,c);
  /* for D-1 */
  EVAL ^= stream_cipher->blength;
  /* Multiply by Q */
  EVAL = MUL64(EVAL,Q,c);
  MAC_I = (uint32_t)(EVAL >> 32) ^ z[4];
  //printf ("MAC_I:%16X\\n",MAC_I);
  MAC_I = hton_int32(MAC_I);
  memcpy(out, &MAC_I, 4);
  return 0;
}

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《Snow 3G算法源码介绍》
《128-bit AES算法源码介绍》
《ZUC算法源码介绍》

【5G/4G】128-EEA1与128-NEA1算法详解
【5G/4G】128-EEA2与128-NEA2算法详解
【5G/4G】128-EEA3与128-NEA3算法详解

【5G/4G】128-EIA1与128-NIA1算法详解
【5G/4G】128-EIA2与128-NIA2算法详解
【5G/4G】128-EIA3与128-NIA3算法详解

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