Chinese encryption SM4 cbc demo

decrypt.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/evp.h>

int main(int argc, const char* argv[])
{
  if (argc <= 1) {
    fprintf(stderr, "Usage: %s <data>\n", argv[0]);
    exit(EXIT_FAILURE);
  }

  const char *key, *iv, *data;
  int key_length, iv_length, data_length;
  key = "1111222233334444";
  key_length = strlen(key);
  iv = "aaaabbbbccccdddd";
  iv_length = strlen(iv);
  data = argv[1];
  data_length = strlen(data);

  const EVP_CIPHER *cipher;
  int cipher_key_length, cipher_iv_length;
  //cipher = EVP_aes_256_gcm();
  //cipher = EVP_aes_256_cbc();
  cipher = EVP_sms4_cbc();
  cipher_key_length = EVP_CIPHER_key_length(cipher);
  cipher_iv_length = EVP_CIPHER_iv_length(cipher);

  if (key_length != cipher_key_length) {
    fprintf(stderr, "Error: key length must be %d\n", cipher_key_length);
    exit(EXIT_FAILURE);
  }
  if (iv_length != cipher_iv_length) {
    fprintf(stderr, "Error: iv length must be %d\n", cipher_iv_length);
    exit(EXIT_FAILURE);
  }

  const char *p;
  char *datax;
  int i, datax_length;

  datax = (char *)malloc(data_length);
  for (p = data, i = 0; *p != '\0'; p += 2, i++) {
    char buf[3];
    buf[0] = *p;
    buf[1] = *(p+1);
    buf[2] = '\0';
    datax[i] = strtol(buf, NULL, 16);
  }
  datax_length = i;

  EVP_CIPHER_CTX *ctx;

  //EVP_CIPHER_CTX_init(ctx);
  ctx = EVP_CIPHER_CTX_new();
  if (ctx == NULL) {
      printf("ctx failed to create.\n");
  }
  EVP_DecryptInit_ex(ctx, cipher, NULL, (unsigned char *)key, (unsigned char *)iv);

  int plain_length, final_length;
  unsigned char *plaintext;

  plain_length = datax_length;
  plaintext = (unsigned char *)malloc(plain_length + 1);

  EVP_DecryptUpdate(ctx, plaintext, &plain_length, (unsigned char *)datax, datax_length);
  EVP_DecryptFinal_ex(ctx, plaintext + plain_length, &final_length);

  plaintext[plain_length + final_length] = '\0';
  printf("Plaintext: %s\n", plaintext);

  free(plaintext);
  free(datax);

  //EVP_CIPHER_CTX_cleanup(&ctx);
  EVP_CIPHER_CTX_free(ctx);
  return 0;
}

encrypt.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/evp.h>

int main(int argc, const char* argv[])
{
  if (argc <= 1) {
    fprintf(stderr, "Usage: %s <data>\n", argv[0]);
    exit(EXIT_FAILURE);
  }

  const char *key, *iv, *data;
  int key_length, iv_length, data_length;
  key = "1111222233334444";
  key_length = strlen(key);
  iv = "aaaabbbbccccdddd";
  iv_length = strlen(iv);
  data = argv[1];
  data_length = strlen(data);

  const EVP_CIPHER *cipher;
  int cipher_key_length, cipher_iv_length;
  //cipher = EVP_aes_256_cbc();
  //cipher = EVP_aes_256_gcm();
  cipher = EVP_sms4_cbc();
  cipher_key_length = EVP_CIPHER_key_length(cipher);
  cipher_iv_length = EVP_CIPHER_iv_length(cipher);

  if (key_length != cipher_key_length) {
    fprintf(stderr, "Error: key length must be %d\n", cipher_key_length);
    exit(EXIT_FAILURE);
  }
  if (iv_length != cipher_iv_length) {
    fprintf(stderr, "Error: iv length must be %d\n", cipher_iv_length);
    exit(EXIT_FAILURE);
  }

  EVP_CIPHER_CTX *ctx;
  //EVP_MD_CTX *ctx;
  ctx = EVP_CIPHER_CTX_new();
  if (ctx == NULL) {
     printf("ctx failed to create.\n");
  }
  int i, cipher_length, final_length;
  unsigned char *ciphertext;

  //EVP_CIPHER_CTX_init(&ctx);
  EVP_EncryptInit_ex(ctx, cipher, NULL, (unsigned char *)key, (unsigned char *)iv);

  cipher_length = data_length + EVP_MAX_BLOCK_LENGTH;
  ciphertext = (unsigned char *)malloc(cipher_length);

  EVP_EncryptUpdate(ctx, ciphertext, &cipher_length, (unsigned char *)data, data_length);
  EVP_EncryptFinal_ex(ctx, ciphertext + cipher_length, &final_length);

  for (i = 0; i < cipher_length + final_length; i++)
    printf("%02x", ciphertext[i]);
  printf("\n");

  free(ciphertext);

  //EVP_CIPHER_CTX_cleanup(&ctx);
  //EVP_MD_CTX_free(ctx);
  EVP_CIPHER_CTX_free(ctx); 
 return 0;
}

Makefile

CFLAGS=-g -std=gnu99 -Wall -pedantic-errors
all: encrypt decrypt
encrypt: encrypt.o
	gcc -o encrypt encrypt.o ./GmSSL/libcrypto.a -lpthread -ldl
encrypt.o: encrypt.c
	gcc -c -o encrypt.o encrypt.c -I/usr/local/include
decrypt: decrypt.o
	gcc -o decrypt decrypt.o ./GmSSL/libcrypto.a -lpthread -ldl
decrypt.o: decrypt.c
	gcc -c -o decrypt.o decrypt.c -I/usr/local/include
clean:
	rm -rf *.o encrypt decrypt