Linux C openssl aes-128-cbc demo

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https://openssl-library.org/source/old/index.html

#include <stdio.h>
#include <string.h>
#include <openssl/aes.h>
#include <openssl/rand.h>
#include <openssl/evp.h>#define AES_KEY_BITS 128
#define GCM_IV_SIZE 12
#define GCM_TAG_SIZE 16int aes_cbc_encrypt(const unsigned char *plaintext,int plaintext_len, const unsigned char *aad,int aad_len, const unsigned char *key,unsigned char *ciphertext, unsigned char *tag)
{EVP_CIPHER_CTX *ctx = NULL;int len = 0;int ciphertext_len = 0;// 创建并初始化 EVP_CIPHER_CTX 对象ctx = EVP_CIPHER_CTX_new();EVP_EncryptInit_ex(ctx, EVP_aes_128_cbc(), NULL, NULL, NULL);// 设置加密密钥EVP_EncryptInit_ex(ctx, NULL, NULL, key, NULL);// 加密明文数据if (EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len) > 0){ciphertext_len = len;}else{printf("Error! \n");}// 结束加密过程，并生成认证标签EVP_EncryptFinal_ex(ctx, ciphertext + len, &len);ciphertext_len += len;EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, GCM_TAG_SIZE, tag);// 释放EVP_CIPHER_CTX对象EVP_CIPHER_CTX_free(ctx);return ciphertext_len;
}int aes_cbc_decrypt(const unsigned char *ciphertext,int ciphertext_len, const unsigned char *aad,int aad_len, const unsigned char *tag,const unsigned char *key, unsigned char *plaintext)
{EVP_CIPHER_CTX *ctx;int len;int plaintext_len;int ret;// 创建并初始化EVP_CIPHER_CTX对象ctx = EVP_CIPHER_CTX_new();EVP_DecryptInit_ex(ctx, EVP_aes_128_cbc(), NULL, NULL, NULL);// 设置解密密钥EVP_DecryptInit_ex(ctx, NULL, NULL, key, NULL);// 设置附加的认证数据（可选）EVP_DecryptUpdate(ctx, NULL, &len, aad, aad_len);// 解密密文数据EVP_DecryptUpdate(ctx, plaintext, &len, ciphertext, ciphertext_len);plaintext_len = len;// 设置接收到的认证标签EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, GCM_TAG_SIZE, (void *)tag);// 结束解密过程，如果认证失败则返回错误ret = EVP_DecryptFinal_ex(ctx, plaintext + len, &len);plaintext_len += len;// 释放EVP_CIPHER_CTX对象EVP_CIPHER_CTX_free(ctx);return ret == 1 ? plaintext_len : -1;
}int main()
{unsigned char key[AES_KEY_BITS / 8];unsigned char iv[GCM_IV_SIZE];unsigned char plaintext[] = "Hello, AES 128!";unsigned char ciphertext[sizeof(plaintext)];unsigned char decryptedtext[sizeof(plaintext)];unsigned char tag[GCM_TAG_SIZE];// 生成密钥if (RAND_bytes(key, sizeof(key)) != 1){printf("error  generating AES key.\n");return 1;}printf("key: \n");for (int i = 0; i < AES_KEY_BITS / 8; i++){printf("0x%0x  ", key[i]);}printf("\n");// 生成初始化向量if (RAND_bytes(iv, sizeof(iv)) != 1){printf("Error generating GCM IV.\n");return 1;}printf("\n");// 加密明文数据int ciphertext_len = aes_cbc_encrypt(plaintext, sizeof(plaintext) - 1, NULL, 0, key, ciphertext, tag);printf("line: %d  ciphertext_len: %d Ciphertext: ", __LINE__, ciphertext_len);for (int i = 0; i < ciphertext_len; i++){printf("%02x", ciphertext[i]);}printf("\n");printf("line: %d  Tag: ", __LINE__);for (int i = 0; i < GCM_TAG_SIZE; i++){printf("%02x", tag[i]);}printf("\n");// 解密密文数据int decryptedtext_len = aes_cbc_decrypt(ciphertext, ciphertext_len, NULL, 0, tag, key, decryptedtext);decryptedtext[decryptedtext_len] = '\0';printf("line: %d  Decrypted text: %s\n", __LINE__, decryptedtext);return 0;
}

编译：

gcc main.c -o main -lssl -lcrypto

使用：

./main

---

读取文件到内存

#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <openssl/bio.h>
#include <sys/stat.h>
#include <sys/types.h>// 修改这，要预算大于文件内容
#define LENGTH 4096#define DEBUG_LOG(fmt, args...)                                           \do                                                                    \{                                                                     \printf("[debug] %s:%d %s() :", __FILE__, __LINE__, __FUNCTION__); \printf(fmt, ##args);                                              \printf("\n");                                                     \} while (0)/*** @brief** @param file_name 文件名称* @param pBuf 传出的文件内容指针* @param bufLen 传出文件内容的长度* @return int*      */
int readFileBuf(const char *file_name, unsigned char **pBuf, int *bufLen)
{FILE *fp = NULL;int numRead = 0;int fileSize = 0;struct stat fileStat;if (NULL == file_name){DEBUG_LOG("input parameter is NULL");return -1;}memset(&fileStat, 0, sizeof(fileStat));if (stat(file_name, &fileStat) < 0){DEBUG_LOG("stat is error!\n");return -1;}else{DEBUG_LOG("size: 0x%X\n", fileStat.st_size);}// 创建跟文件大小一样的 buffileSize = fileStat.st_size;*pBuf = (unsigned char *)malloc(fileSize);if (NULL == *pBuf){DEBUG_LOG("malloc failed\n");return -1;}if ((fp = fopen(file_name, "r")) == NULL){DEBUG_LOG("open %s failed.\n", file_name);return -1;}numRead = fread(*pBuf, sizeof(unsigned char), fileSize, fp);if (numRead < fileSize){DEBUG_LOG("read file data failed.\n");fclose(fp);free(pBuf);return -1;}else{DEBUG_LOG("read file data success. fileSize: %d\n", fileSize);*bufLen = fileSize;}fclose(fp);return fileSize;
}int main()
{int numRead = 0;unsigned char *pBuf = NULL;// 目标文件const char *fileName = "./openssl-3.3.2.tar.gz";int length = 0;// 注意传进的 pBuf 是二重指针numRead = readFileBuf(fileName, &pBuf, &length);if (numRead > 0){DEBUG_LOG("length = %d\n", length);}// BIO_dump_fp(stdout, pBuf, length);free(pBuf);return 0;
}