#微码分享#AES算法的C++包装类

AES为Advanced Encryption Standard的缩写,中文名:高级加密标准,在密码学中又称Rijndael加密法,是美国联邦政府采用的一种区块加密标准,用来替代DES。基于std::string实现的C++包装类,使用得应用AES算法十分简单。完整源代码链接: https://github.com/eyjian/libmooon/blob/master/include/mooon/utils/aes_helper.h https://github.com/eyjian/libmooon/blob/master/src/utils/aes_helper.cpp aes_helper.h头文件

 // 高级加密标准(Advanced Encryption Standard),
  
 // 在密码学中又称Rijndael加密法,是美国联邦政府采用的一种区块加密标准,用来替代DES
 
 class CAESHelper
 
 {
 
 public:
 
 // 加密数据块分组长度,必须为128比特(密钥长度可以是128比特、192比特、256比特中的任意一个)
 
 			    static int aes_block_size;
 
 
 
 public:
 
 // key 密钥
 
 //
 
 // 因为AES要求key长度只能为128或192或256比特中的一种,即16字节或24字节或32字节中的一种,
 
 // 当key的长度不足16字节时,CAESHelper自动补0足16字节,
 
 // 当key的长度间于16字节和24字节时,CAESHelper自动补0足24字节,
 
 // 当key的长度间于24字节和32字节时,CAESHelper自动补0足32字节,
 
 // 当key的长度超出32字节时,CAESHelper自动截取前32字节作为密钥
 
 			    CAESHelper(const std::string& key);
 
 ~CAESHelper();
 
 
 
 			    void encrypt(const std::string& in, std::string* out);
 
 			    void decrypt(const std::string& in, std::string* out);
 
 
 
 private:
 
 // flag 为true表示加密,为false表示解密
 
 			    void aes(bool flag, const std::string& in, std::string* out, void* aes_key);
 
 
 
 private:
 
 			    void* _encrypt_key;
 
 			    void* _decrypt_key;
 
 			    std::string _key;
 
 };  

aes_helper.cpp文件

 #if MOOON_HAVE_OPENSSL == 1
  
 int CAESHelper::aes_block_size = AES_BLOCK_SIZE; // 16
 
 			#else
 
 int CAESHelper::aes_block_size = 0;
 
 			#endif // MOOON_HAVE_OPENSSL
 
 
 
 			static std::string errcode2errmsg(int errcode)
 
 {
 
 			    std::string errmsg;
 
 
 
 if (0 == errcode)
 
 			        errmsg = "success";
 
 else if (-1 == errcode)
 
 			        errmsg = "userkey is empty";
 
 else if (-2 == errcode)
 
 			        errmsg = "length of userkey is invalid";
 
 else
 
 			        errmsg = "unknown error";
 
 			    return errmsg;
 
 }
 
 
 
 			CAESHelper::CAESHelper(const std::string& key)
 
 {
 
 			    _encrypt_key = NULL;
 
 			    _decrypt_key = NULL;
 
 			    _key = key;
 
 
 
 const std::string::size_type LEN16 = 16;
 
 const std::string::size_type LEN24 = 24;
 
 const std::string::size_type LEN32 = 32;
 
 const std::string::size_type len = key.size();
 
 if ((len != LEN16) &&
 
 (len != LEN24) &&
 
 (len != LEN32))
 
 {
 
 if (len < LEN16)
 
 			            _key.resize(LEN16);
 
 else if (len < LEN24)
 
 			            _key.resize(LEN24);
 
 else if (len < LEN32)
 
 			            _key.resize(LEN32);
 
 else
 
 			            _key.resize(LEN32);
 
 }
 
 }
 
 
 
 			CAESHelper::~CAESHelper()
 
 {
 
 			#if MOOON_HAVE_OPENSSL == 1
 
 			    delete (AES_KEY*)_encrypt_key;
 
 			    delete (AES_KEY*)_decrypt_key;
 
 			#endif // MOOON_HAVE_OPENSSL
 
 }
 
 
 
 			void CAESHelper::encrypt(const std::string& in, std::string* out)
 
 {
 
 			#if MOOON_HAVE_OPENSSL == 1
 
 if (NULL == _encrypt_key)
 
 {
 
 			        _encrypt_key = new AES_KEY;
 
 
 
 const int errcode = AES_set_encrypt_key((const unsigned char*)(_key.data()), (int)(_key.size()*8), (AES_KEY*)_encrypt_key);
 
 if (errcode != 0) // 理论上不会返回非0,因为构造函数已经处理好了key的长度
 
 {
 
 			            delete (AES_KEY*)_encrypt_key;
 
 			            _encrypt_key = NULL;
 
 			            THROW_EXCEPTION(errcode2errmsg(errcode), errcode);
 
 }
 
 }
 
 
 
 			    aes(true, in, out, _encrypt_key);
 
 			#endif // MOOON_HAVE_OPENSSL
 
 }
 
 
 
 			void CAESHelper::decrypt(const std::string& in, std::string* out)
 
 {
 
 			#if MOOON_HAVE_OPENSSL == 1
 
 if (NULL == _decrypt_key)
 
 {
 
 			        _decrypt_key = new AES_KEY;
 
 
 
 const int errcode = AES_set_decrypt_key((const unsigned char*)(_key.data()), (int)(_key.size()*8), (AES_KEY*)_decrypt_key);
 
 if (errcode != 0) // 理论上不会返回非0,因为构造函数已经处理好了key的长度
 
 {
 
 			            delete (AES_KEY*)_decrypt_key;
 
 			            _decrypt_key = NULL;
 
 			            THROW_EXCEPTION(errcode2errmsg(errcode), errcode);
 
 }
 
 }
 
 
 
 			    aes(false, in, out, _decrypt_key);
 
 			#endif // MOOON_HAVE_OPENSSL
 
 }
 
 
 
 			void CAESHelper::aes(bool flag, const std::string& in, std::string* out, void* aes_key)
 
 {
 
 			#if MOOON_HAVE_OPENSSL == 1
 
 			    AES_KEY* aes_key_ = (AES_KEY*)aes_key;
 
 
 
 			    std::string in_tmp = in;
 
 if (in.size() % AES_BLOCK_SIZE != 0)
 
 {
 
 			        std::string::size_type tmp_size = in.size() + (AES_BLOCK_SIZE - in.size() % AES_BLOCK_SIZE);
 
 			        in_tmp.resize(tmp_size);
 
 }
 
 
 
 const char* in_p = in_tmp.data();
 
 			    out->resize(in_tmp.size());
 
 			    char* out_p = const_cast<char*>(out->data());
 
 
 
 for (std::string::size_type i=0; i<in.size(); i+=AES_BLOCK_SIZE)
 
 {
 
 			        char out_tmp[AES_BLOCK_SIZE];
 
 
 
 if (flag)
 
 			            AES_encrypt((const unsigned char*)(in_p), (unsigned char*)(out_tmp), aes_key_);
 
 else
 
 			            AES_decrypt((const unsigned char*)(in_p), (unsigned char*)(out_tmp), aes_key_);
 
 
 
 			        in_p += AES_BLOCK_SIZE;
 
 			        memcpy(out_p+i, out_tmp, AES_BLOCK_SIZE);
 
 }
 
 			#else
 
 *out = '\0'; // 需要加上这一句,不然难区分HAVE_OPENSSL值是否为1或不为1的情况
 
 			#endif // MOOON_HAVE_OPENSSL
 
 } 

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