openssl的aes128_ECB加密解密运算实例

aes128算法ECB接口

加密接口

注意事项：

• EVP_EncryptInit_ex初始化算法EVP_aes_128_ecb()，和密钥，key至少16B
• EVP_EncryptUpdate加密运算，tmplen输出已加密长度
• EVP_EncryptFinal_ex结束运算，如果在此仍有加密运算，则加密长度tmplen需补充到密文长度中

int openssl_aes128_encrypt_ecb(unsigned char *key,unsigned char *iv, unsigned char *in_buf, int in_len, unsigned char *out_buf,int* out_len)
{
    EVP_CIPHER_CTX* ctx = NULL;
    ctx = EVP_CIPHER_CTX_new();
    int tmplen = 0;
    printf("%s %d\n", __func__, __LINE__);
    EVP_EncryptInit_ex(ctx, EVP_aes_128_ecb(), NULL, key, NULL);
    
    if (!EVP_EncryptUpdate(ctx, out_buf, &tmplen, in_buf, in_len))
    {
        EVP_CIPHER_CTX_free(ctx);
        return -1;
    }
    *out_len = tmplen;

    if (!EVP_EncryptFinal_ex(ctx, out_buf + *out_len, &tmplen))
    {
        EVP_CIPHER_CTX_free(ctx);
        return -2;
    }
 
    *out_len += tmplen;
    EVP_CIPHER_CTX_free(ctx);
    return 0 ;
}

解密接口

注意事项：

• EVP_DecryptInit_ex初始化算法EVP_aes_128_ecb()，和密钥，key至少16B
• EVP_DecryptUpdate解密运算，tmplen输出已解密长度
• 如果剩余字节是16B，再次使用EVP_DecryptUpdate
• 如果剩余字节不是16B整数倍，使用EVP_EncryptFinal_ex结束运算，输出加密长度tmplen补充到密文长度中

int openssl_aes128_decrypt_ecb(unsigned char *key,unsigned char *iv, unsigned char *in_buf, int in_len, unsigned char *out_buf,int* out_len)
{
    int ret = 0 ,tmplen = 0;
    EVP_CIPHER_CTX* ctx = NULL;
    ctx = EVP_CIPHER_CTX_new();
    EVP_CIPHER_CTX_set_padding(ctx, 0);
    printf("%s %d\n", __func__, __LINE__);

    EVP_DecryptInit_ex(ctx, EVP_aes_128_ecb(), NULL, key, NULL);

    if (!EVP_DecryptUpdate(ctx, out_buf, &tmplen, in_buf, in_len))
    {
        EVP_CIPHER_CTX_free(ctx);
        return -1;
    }
    *out_len = tmplen;

    if (in_len > tmplen) {
        if (!EVP_DecryptUpdate(ctx, out_buf+tmplen, &tmplen, in_buf+tmplen, in_len-tmplen))
        {
        //        RSP_TRACE("%s EVP_DecryptUpdate error \n", __func__);
            EVP_CIPHER_CTX_free(ctx);
            return -1;
        }
        *out_len += tmplen;
    }

    if (in_len %16!=0){
        ret = EVP_DecryptFinal_ex(ctx, out_buf+tmplen, &tmplen);
        fprintf(stderr, "err:\n");
        if (ret != 0)
        {
        //        RSP_TRACE("%s EVP_DecryptFinal_ex error ret=%d\n", __func__, ret);
            EVP_CIPHER_CTX_free(ctx);
            return -2;
        }
        *out_len += tmplen;
    }

    EVP_CIPHER_CTX_free(ctx);
    return 0 ;
}