题
我很无聊,写了一个 openSSL 的包装器来用更少的工作进行 AES 加密。如果我这样做:http://pastebin.com/V1eqz4jp (伊维茨 = 0)
一切工作正常,但默认的ivec全为0,这存在一些安全问题。既然我无论如何都将数据作为字符串传递回来,我想,为什么不生成一个随机的 ivec 并将其粘贴到前面,当我解密字符串时将其取回呢?由于某种原因它不起作用。
事实上,它几乎可以工作。它似乎解密了字符串的中间部分,但没有解密开头 或结束:
String is: 0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF
Encrypting..
���l%%1u���B!
�����`pN)�ɶ���[l�ӏ��{�Q�?�2�/�HԵ�y"�=Z�Cu����l%%1u���B!
Decrypting..
String is: �%���G*�5J�0��0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF
老实说,我不知道出了什么问题。也许是一些愚蠢的错误,或者也许我遗漏了一些关于 AES 的东西?
这是代码:(编辑以纳入史蒂夫·杰索普对我的第一个问题的解决方案)
/*!
* Simple AES
* Brendan Long
* March 29, 2010
*
* Simplified encryption and decryption using OpenSSL's AES library.
* Remember to compile with -lcrypto and link against the library
* g++ (your stuff) -lcrypto simpleAes.cpp (or simpleAes.o)
*
* Implementation note: Using the default ivec (0) is not secure. For
* the full security that AES offers, use a different
* ivec each time (it does not need to be secret,
* just different.
*
* This code is released into the public domain. Yada yada..
* Read this for details: http://creativecommons.org/licenses/publicdomain/
*
* If for some reason public domain isn't good enough, you may use, alter,
* distribute or do anything else you want with this code with no restrictions.
*/
#include <openssl/aes.h>
#include <iostream>
#include <stdlib.h>
#include <time.h>
bool seed = true;
/*!
* Encrypts a string using AES with a 256 bit key
* Note: If the key is less than 32 bytes, it will be null padded.
* If the key is greater than 32 bytes, it will be truncated
* \param in The string to encrypt
* \param key The key to encrypt with
* \return The encrypted data
*/
std::string aes_encrypt(std::string in, std::string key){
// Seed the random number generator once
if(seed){
srand( (unsigned int) time(NULL));
seed = false;
}
// Generate a random ivec
unsigned char ivec[16];
for(int i=0; i<16; i++){
ivec[i] = (unsigned char) rand();
}
// Round up to AES_BLOCK_SIZE
size_t textLength = ((in.length() / AES_BLOCK_SIZE) + 1) * AES_BLOCK_SIZE;
// Always pad the key to 32 bits.. because we can
if(key.length() < 32){
key.append(32 - key.length(), '\0');
}
// Get some space ready for the output
unsigned char *output = new unsigned char[textLength];
// Generate a key
AES_KEY *aesKey = new AES_KEY;
AES_set_encrypt_key((unsigned char*)key.c_str(), 256, aesKey);
// Encrypt the data
AES_cbc_encrypt((unsigned char*)in.c_str(), output, in.length() + 1, aesKey, ivec, AES_ENCRYPT);
// Make the data into a string
std::string ret((char*) output, textLength);
// Add the ivec to the front
ret = std::string((char*)ivec, 16) + ret;
// Clean up
delete output;
delete aesKey;
return ret;
}
/*!
* Decrypts a string using AES with a 256 bit key
* Note: If the key is less than 32 bytes, it will be null padded.
* If the key is greater than 32 bytes, it will be truncated
* \param in The string to decrypt
* \param key The key to decrypt with
* \return The decrypted data
*/
std::string aes_decrypt(std::string in, std::string key){
// Get the ivec from the front
unsigned char ivec[16];
for(int i=0;i<16; i++){
ivec[i] = in[i];
}
in = in.substr(16);
// Always pad the key to 32 bits.. because we can
if(key.length() < 32){
key.append(32 - key.length(), '\0');
}
// Create some space for output
unsigned char *output = new unsigned char[in.length()];
// Generate a key
AES_KEY *aesKey = new AES_KEY;
AES_set_decrypt_key((unsigned char*)key.c_str(), 256, aesKey); // key length is in bits, so 32 * 8 = 256
// Decrypt the data
AES_cbc_encrypt((unsigned char*)in.c_str(), output, in.length(), aesKey, ivec, AES_DECRYPT);
// Make the output into a string
std::string ret((char*) output);
// Clean up
delete output;
delete aesKey;
return ret;
}
解决方案 3
我的一个朋友发现了这个问题。我正在这样做:
- 生成随机数并将其存储在
ivec
- 加密数据
ivec
- 将 ivec 附加到输出数据的开头
问题是步骤 2 改变了 ivec 的内容。我基本上是在字符串的开头存储随机数。解决方案是添加以下内容:
unsigned char ivec[16];
// set ivec to random numbers
std::string ivecString((char*) ivec, 16);
// encrypt data
return ivecString + encryptedData;
其他提示
您应该保存IVEC [16]成 '输出' BEFORE加密。 就是这样...
我也会喜欢补充说,这将是更加简单使用char *的工作,而不是字符串。
此线是错误的:
std::string ret((char*) output);
解密的数据不具有一个NUL终止子,因为你加密in.length()
字节。这占末尾的垃圾,而不是在一开始的垃圾。可能有其他问题,以及
在一般情况下,你不能把加密级的输出作为一个字符串,除非你执行一个附加步骤,如Base 64编码的输出。任何输出字节可能是一个NUL。
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