利用openssl实现字符串加密解密

#include <string.h>#include <stdio.h>#include <stdlib.h>#include <openssl/aes.h>#include <openssl/evp.h>#define EVP_DES_CBC EVP_des_cbc()//#define EVP_DES_CBC EVP_aes_128_cbc();#define MAX_CHAR_SIZE 512unsigned char *decrypt_text(unsigned char *iv, unsigned char *key, unsigned char *ciphertext,int *ciphertext_len,unsigned char* plaintext) {   EVP_CIPHER_CTX de;  EVP_CIPHER_CTX_init(&de);  const EVP_CIPHER *cipher_type;  int bytes_written = 0;  int update_len = 0;  cipher_type = EVP_DES_CBC;//  rc = EVP_CIPHER_CTX_set_key_length(&de, strlen(pstRedirectConf->key));  EVP_DecryptInit_ex(&de, cipher_type, NULL, key, iv);  if(!EVP_DecryptInit_ex(&de, NULL, NULL, NULL, NULL)){    printf("ERROR in EVP_DecryptInit_ex \n");    return NULL;  }  int plaintext_len = 0;  if(!EVP_DecryptUpdate(&de,                        plaintext, &update_len,                        ciphertext, *ciphertext_len)){    printf("ERROR in EVP_DecryptUpdate\n");    return NULL;  }  if(!EVP_DecryptFinal_ex(&de,                          plaintext + update_len, &bytes_written)){    printf("ERROR in EVP_DecryptFinal_ex\n");    return NULL;  }  bytes_written += update_len;  *(plaintext+bytes_written) = '\0';  printf("out_buf(%d->%d) : %s\n", *ciphertext_len,bytes_written, plaintext);  EVP_CIPHER_CTX_cleanup(&de);  return plaintext;}unsigned char *encrypt_text(unsigned char *iv, unsigned char *key, unsigned char *plaintext,int *ciphertext_len,unsigned char *ciphertext ) {   EVP_CIPHER_CTX en;  EVP_CIPHER_CTX_init(&en);  const EVP_CIPHER *cipher_type;  int input_len = 0;  //  cipher_type = EVP_aes_128_cbc();  cipher_type = EVP_DES_CBC;  //init cipher  EVP_EncryptInit_ex(&en, cipher_type, NULL, key, iv);  // We add 1 because we're encrypting a string, which has a NULL terminator  // and want that NULL terminator to be present when we decrypt.//  input_len = strlen(plaintext) + 1;  input_len = strlen(plaintext);  /* allows reusing of 'e' for multiple encryption cycles */  if(!EVP_EncryptInit_ex(&en, NULL, NULL, NULL, NULL)){    printf("ERROR in EVP_EncryptInit_ex \n");    return NULL;  }  // This function works on binary data, not strings.  So we cast our  // string to an unsigned char * and tell it that the length is the string  // length + 1 byte for the null terminator.  int bytes_written = 0;  //encrypt  if(!EVP_EncryptUpdate(&en,                        ciphertext, &bytes_written,                        (unsigned char *) plaintext, input_len ) ) {    return NULL;  }  *ciphertext_len += bytes_written;  //do padding  if(!EVP_EncryptFinal_ex(&en,                          ciphertext + bytes_written,                          &bytes_written)){    printf("ERROR in EVP_EncryptFinal_ex \n");    return NULL;  }  *ciphertext_len += bytes_written;  int i = 0;  printf("encrypt string: ");  for( i =0;i < *ciphertext_len; i++)      printf("%.02x", ciphertext[i]);  printf("\n");  //cleanup  EVP_CIPHER_CTX_cleanup(&en);  return ciphertext;}int main(int argc, char **argv) {    unsigned char * in = "hello world,yesterday once more!!!!!!!!!!!";//    static char *in="Once More Yesterday";    printf("Input: %s\n", in);    unsigned char * out = NULL;    unsigned char * final = NULL;    //out = (unsigned char *) malloc(strlen(in));    unsigned char * iv = "aaaaaaaaaaaaaaaa";    unsigned char * key = "bbbbbbbbbbbbbbbb";    int ciphertext_len = 0;    unsigned char ciphertext[MAX_CHAR_SIZE];    unsigned char plaintext[MAX_CHAR_SIZE];    out = encrypt_text(iv, key, in, &ciphertext_len,ciphertext);    printf("in: %s([%d] - > out:[%d])\n", in,strlen(in) ,ciphertext_len);    final = decrypt_text(iv, key, out,&ciphertext_len,plaintext);     printf("final: %s[%d]\n", final,strlen(final));    return 0;}