IDEA算法c语言实现

毕业设计要做IDEA密码算法的安全性分析，先写个算法实现代码，以备后用。

/* IDEA.h */ #ifndef IDEA_H #define IDEA_H /* define return status */ #define IDEA_SUCCESS 0 #define IDEA_ERROR 1 /* define data length */ #define IDEA_KEY_LEN 128 #define IDEA_BLOCK_SIZE 64 #define IDEA_SUB_BLOCK_SIZE 16 /* define global variable */ #define IDEA_ADD_MODULAR 65536 #define IDEA_MP_MODULAR 65537 /* define operation mode */ #define ECB 0 #define CBC 1 #define CFB 2 #define OFB 3 /* define data type */ //typedef bool bit_t, status_t; typedef unsigned char byte_t, uint8_t; typedef unsigned short word_t, uint16_t; typedef unsigned int dword_t, uint32_t, status_t; typedef unsigned long long uint64_t; /* declare fuction */ status_t idea_encrypt(uint64_t plaintext, uint16_t key[8], uint64_t *ciphertext); status_t idea_decrypt(uint64_t ciphertext, uint16_t key[8], uint64_t *plaintext); status_t idea_round(uint16_t X[4], uint16_t Z[6], uint16_t out[4]); status_t MA(uint16_t ma_in[2], uint16_t sub_key[2],uint16_t ma_out[2]); status_t subkey_generation(uint16_t key[8], uint16_t sub_key[52]); status_t subdkey_generation(uint16_t key[8], uint16_t sub_dkey[52]); status_t extended_eucild(uint16_t d, uint32_t k, uint32_t *result); #endif

/* IDEA(International Data Encryption Algorithm), refer to http://www.quadibloc.com/crypto/co040302.htm * IDEA.c, an IDEA encryption and decryption program. * Author shenyang * Mar. 4th, 2011 * TODO: Fault analysis on IDEA, defence of fault analysis on IDEA. */ #ifndef IDEA_H #include "IDEA.h" #endif #include <string.h> #include <stdio.h> /* define operation */ static uint16_t add_mod(uint16_t a, uint16_t b); static uint16_t mp_mod(uint16_t a,uint16_t b); static uint16_t XOR(uint16_t a, uint16_t b); static status_t left_shift(uint16_t key[8], int num); static void swap(uint16_t *a, uint16_t *b); /* addition and mod 65536 */ static uint16_t add_mod(uint16_t a, uint16_t b) { uint32_t tmp = a+b; uint16_t ret = tmp % IDEA_ADD_MODULAR; return ret; } /* multiply and mod 65537 */ static uint16_t mp_mod(uint16_t a,uint16_t b) { /* Note: In IDEA, for purposes of multiplication, a 16 bit word containing all zeroes is considered to represent the number 65,536; * other numbers are represented in conventional unsigned notation, and multiplication is modulo the prime number 65,537 */ uint64_t tmp, tmp_a, tmp_b; //if both a and b are 2^16, the result will be 2^32 which will exceed a 32-bit int tmp_a = a==0 ? (1<<16) : a; tmp_b = b==0 ? (1<<16) : b; tmp = (tmp_a * tmp_b) % IDEA_MP_MODULAR; return (uint16_t)(tmp); } /* XOR */ static uint16_t XOR(uint16_t a, uint16_t b) { return a^b; } static void swap(uint16_t *a, uint16_t *b) { uint16_t c = 0; c = *a; *a = *b; *b = c; } /* IDEA encryption */ status_t idea_encrypt(uint64_t plaintext, uint16_t key[8], uint64_t *ciphertext) { uint16_t X[4], sub_key[52], out[4]; status_t st; int i, j; /* cut 64-bit plaintext into 4 16-bit sub blocks */ for(i = 0; i < 4; i++) X[i] = (plaintext >> (48-i*16)) & 0xffff; /* generate sub keys */ st = subkey_generation(key, sub_key); for(i = 0; i < 8; i++) { idea_round(X, &(sub_key[i*6]), out); for(j = 0; j < 4; j++) X[j] = out[j]; } /* round 9, do output transform */ //Note that the swap of B and C is not performed after round 8. So we swap them again. swap(&(out[1]), &(out[2])); out[0] = mp_mod(out[0], sub_key[48]); out[1] = add_mod(out[1], sub_key[49]); out[2] = add_mod(out[2], sub_key[50]); out[3] = mp_mod(out[3], sub_key[51]); *ciphertext = out[0]; for(i = 1; i <= 3; i++) *ciphertext = ((*ciphertext)<<16)|out[i]; return st; } /* IDEA decryption */ status_t idea_decrypt(uint64_t ciphertext, uint16_t key[8], uint64_t *plaintext) { status_t st; uint16_t X[4], sub_dkey[52], out[4]; int i, j; for(i = 0; i < 4; i++) X[i] = (ciphertext >> (48-i*16)) & 0xffff; /* generate sub keys for decryption*/ st = subdkey_generation(key, sub_dkey); if(st != IDEA_SUCCESS) return st; for(i = 0; i < 8; i++) { idea_round(X, &(sub_dkey[i*6]), out); for(j = 0; j < 4; j++) X[j] = out[j]; } out[0] = mp_mod(out[0], sub_dkey[48]); out[1] = add_mod(out[1], sub_dkey[49]); out[2] = add_mod(out[2], sub_dkey[50]); out[3] = mp_mod(out[3], sub_dkey[51]); swap(&(out[1]), &(out[2])); //Note that the unswap in decryption is called after transform, that is different from the encryption. *plaintext = out[0]; for(i = 1; i <= 3; i++) *plaintext = ((*plaintext)<<16) | out[i]; return st; } status_t idea_round(uint16_t X[4], uint16_t Z[6], uint16_t out[4]) { status_t st; uint16_t tmp[4], ma_in[2], ma_out[2]; tmp[0] = mp_mod(X[0], Z[0]); //step 1. multiply X1 by 1st sub key tmp[1] = add_mod(X[1], Z[1]); //step 2. add X2 to 2nd sub key tmp[2] = add_mod(X[2], Z[2]); //step 3. add X3 to 3rd sub key tmp[3] = mp_mod(X[3], Z[3]); //step 4. multiply X4 by 4th sub key ma_in[0] = XOR(tmp[0], tmp[2]); //step 5. XOR results in step 1 and step 3 ma_in[1] = XOR(tmp[1], tmp[3]); //step 6. XOR results in step 2 and step 4 st = MA(ma_in, &Z[4], ma_out); //step 7. MA diffusion /* step 8. generate the output*/ out[0] = XOR(tmp[0], ma_out[1]); out[1] = XOR(tmp[1], ma_out[0]); out[2] = XOR(tmp[2], ma_out[1]); out[3] = XOR(tmp[3], ma_out[0]); swap(&(out[1]), &(out[2])); return st; } /* MA diffusion */ status_t MA(uint16_t ma_in[2], uint16_t sub_key[2],uint16_t ma_out[2]) { uint16_t tmp[2]; tmp[0] = mp_mod(ma_in[0], sub_key[0]); tmp[1] = add_mod(ma_in[1], tmp[0]); ma_out[1] = mp_mod(tmp[1], sub_key[1]); ma_out[0] = add_mod(tmp[0], ma_out[1]); return IDEA_SUCCESS; } /* sub keys generation */ status_t subkey_generation(uint16_t key[8], uint16_t sub_key[52]) { int i, j; uint16_t tmp_key[8]; for(i = 0; i < 8; i++) tmp_key[i] = key[i]; for(i = 0; i < 6; i++) { for(j = 0; j < 8; j++) sub_key[i*8+j] = tmp_key[j]; left_shift(tmp_key, 25); } for(i = 0; i < 4; i++) sub_key[48+i] = tmp_key[i]; return IDEA_SUCCESS; } /* sub dkeys generation * *The decryption key schedule is: * *The first four subkeys for decryption are: * *KD(1) = 1/K(49) *KD(2) = -K(50) *KD(3) = -K(51) *KD(4) = 1/K(52) * *and they do not quite follow the same pattern as the remaining subkeys which follow. * *The following is repeated eight times, adding 6 to every decryption key's index and subtracting 6 from every encryption key's index: * *KD(5) = K(47) *KD(6) = K(48) * *KD(7) = 1/K(43) *KD(8) = -K(45) *KD(9) = -K(44) *KD(10) = 1/K(46) * */ status_t subdkey_generation(uint16_t key[8], uint16_t sub_dkey[52]) { status_t st; int i; uint16_t sub_key[52]; uint32_t tmp; st = subkey_generation(key, sub_key); st = extended_eucild(sub_key[48], IDEA_MP_MODULAR, &tmp); if(st != IDEA_SUCCESS) { printf("subdkey_generation error!/n"); return st; } sub_dkey[0] = tmp == 65536 ? 0 : (uint16_t)tmp; sub_dkey[1] = (IDEA_ADD_MODULAR - sub_key[49]) % IDEA_ADD_MODULAR; sub_dkey[2] = (IDEA_ADD_MODULAR - sub_key[50]) % IDEA_ADD_MODULAR; st = extended_eucild(sub_key[51], IDEA_MP_MODULAR, &tmp); if(st != IDEA_SUCCESS) { printf("subdkey_generation error!/n"); return st; } sub_dkey[3] = tmp == 65536 ? 0 : (uint16_t)tmp; for(i = 0; i < 8; i++) //This is awful?!...May be I should make a table. { sub_dkey[4+i*6] = sub_key[52-(i+1)*6]; sub_dkey[4+i*6+1] = sub_key[52-(i+1)*6+1]; st = extended_eucild(sub_key[52-(i+1)*6-4], IDEA_MP_MODULAR, &tmp); if(st != IDEA_SUCCESS) { printf("subdkey_generation error!/n"); return st; } sub_dkey[4+i*6+2] = tmp == 65536 ? 0 : (uint16_t)tmp; sub_dkey[4+i*6+3] = (IDEA_ADD_MODULAR - sub_key[52-(i+1)*6-2]) % IDEA_ADD_MODULAR; sub_dkey[4+i*6+4] = (IDEA_ADD_MODULAR - sub_key[52-(i+1)*6-3]) % IDEA_ADD_MODULAR; st = extended_eucild(sub_key[52-(i+1)*6-1], IDEA_MP_MODULAR, &tmp); if(st != IDEA_SUCCESS) { printf("subdkey_generation error!/n"); return st; } sub_dkey[4+i*6+5] = tmp == 65536 ? 0 : (uint16_t)tmp; } return IDEA_SUCCESS; } /* left shift */ static status_t left_shift(uint16_t key[8], int num) { uint16_t copy_key[8]; int i; for(i = 0; i < 8; i++) copy_key[i] = key[i]; for(i = 0; i < 8; i++) key[i] = (copy_key[(i+num/16)%8]<<(num%16)) | (copy_key[(i+num/16+1)%8]>>(16-num%16)); return IDEA_SUCCESS; } /* Extended Eucild Algorithm to caculate d^-1 mod k*/ status_t extended_eucild(uint16_t d, uint32_t k, uint32_t *result) { int x[4], y[4], t[4], q; int i; x[1] = x[2] = 0; x[3] = k; y[1] = 0, y[2] = 1; y[3] = d == 0 ? (1<<16) : d; while(y[3] > 1) { q = x[3] / y[3]; for(i = 1; i <= 3; i++) t[i] = x[i] - q*y[i]; for(i = 1; i <= 3; i++) x[i] = y[i]; for(i = 1; i <= 3; i++) y[i] = t[i]; } if(y[3] == 1) { if(y[2] < 0) y[2] += k; *result = y[2]; return IDEA_SUCCESS; } else return IDEA_ERROR; }

/* a simple test program of IDEA encryption and decryption. * Author shenyang * */ #include <stdio.h> #include <string.h> #include "IDEA.h" void usage() { printf("Usage: IDEA [-e(encrypt)|-d(decrypt)]/n"); } void encrypt() { uint16_t key[8]; uint64_t plaintext[1024], ciphertext[1024]; char str[1024]; int block_cnt = 0, i = 0, len; printf("/ninput plaintext(in hex):"); scanf("%s", str); len = strlen(str); for(; len%16 != 0; len++)//fill the text with '0' such that it can be cut into 64-bit blocks. str[len] = '0'; str[len] = '/0'; while(sscanf(str+block_cnt*16, "%016llx", &(plaintext[block_cnt]))!=EOF)//4x16=64 block_cnt++; /*while(sscanf(str+block_cnt*4, "%04hx", &(tmp[block_cnt]))!=EOF) block_cnt++; for(i = 0; i*4 < block_cnt; i++) { plaintext[i] = tmp[i*4]; for(j = 1; j < 4; j++) plaintext[i] = (plaintext[i]<<16)|tmp[i*4+j]; } block_cnt /= 4;*/ printf("/ninput 128-bit secret key(in hex):"); scanf("%s", str); len = strlen(str); if(len > 32) { printf("/nsecret key too long"); return ; } for(; len < 32; len++) str[len] = '0'; str[len] = '/0'; for(i = 0; i < 8; i++) sscanf(str+i*4, "%04hx", &key[i]); printf("/nciphertext = "); for(i = 0; i < block_cnt; i++) { idea_encrypt(plaintext[i], key, &(ciphertext[i])); printf("%016llx", ciphertext[i]); } printf("/n"); } void decrypt() { uint16_t key[8]; uint64_t plaintext[1024], ciphertext[1024]; char str[1024]; int block_cnt = 0, i = 0, len; printf("/ninput ciphertext(in hex):"); scanf("%s", str); len = strlen(str); for(; len%16 != 0; len++) str[len] = '0'; str[len] = '/0'; while(sscanf(str+block_cnt*16, "%016llx", &(ciphertext[block_cnt]))!=EOF) block_cnt++; /*while(sscanf(str+block_cnt*4, "%04hx", &(tmp[block_cnt]))!=EOF) block_cnt++; for(i = 0; i*4 < block_cnt; i++) { ciphertext[i] = tmp[i*4]; for(j = 1; j < 4; j++) ciphertext[i] = (ciphertext[i]<<16)|tmp[i*4+j]; } block_cnt /= 4;*/ printf("/ninput 128-bit secret key(in hex):"); scanf("%s", str); len = strlen(str); if(len > 32) { printf("/nsecret key too long"); return ; } for(; len < 32; len++) str[len] = '0'; str[len] = '/0'; for(i = 0; i < 8; i++) sscanf(str+i*4, "%04hx", &key[i]); printf("/nplaintext = "); for(i = 0; i < block_cnt; i++) { idea_decrypt(ciphertext[i], key, &(plaintext[i])); printf("%016llx", plaintext[i]); } printf("/n"); } int main(int argc, char **argv) { if(argc < 2) { usage(); return 1; } if(argv[1][0] != '-') { usage(); return 1; } switch(argv[1][1]) { case 'e': case 'E': encrypt(); break; case 'd': case 'D': decrypt(); break; default: usage(); return 1; } return 0; }

要注意的是不同环境下读64位整数的方式不同，可能要把%llx改成%I64x.