xcode Objective-C 解密 AES 128 cbc 十六进制字符串
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Objective-C decrypt AES 128 cbc hex string
提问by pasqui86
I am developing an application for iPhone on Snow Leopard with Xcode 3.1 that receives from a restful web service an encrypted text in hexadecimal format with the algorithm AES 128-bit (CBC). The algorithm uses an initialization vector + secret key. How do I decrypt this text? Thanks to everyone for the tips that I will succeed in giving.
我正在使用 Xcode 3.1 在 Snow Leopard 上开发 iPhone 应用程序，该应用程序从宁静的 Web 服务接收十六进制格式的加密文本，采用 AES 128 位 (CBC) 算法。该算法使用初始化向量 + 密钥。如何解密此文本？感谢大家的提示，我将成功地给予。
EDIT: I get response from REST Server in hex AND crypted format,I try with this code but i receive always bad param error. Can you help me to find the error? Is it possible that i firstly convert the string response into binary format?
编辑：我从 REST 服务器收到十六进制和加密格式的响应，我尝试使用此代码，但我总是收到错误的参数错误。你能帮我找出错误吗？是否有可能我首先将字符串响应转换为二进制格式？
NSString *response = [request responseString];
NSData *encryptedData = [response dataUsingEncoding: NSASCIIStringEncoding];
NSString *key = @"32charlength";
NSString *iv = @"16charlength";
NSData *unencryptedData = NULL;
size_t unencryptedLength = [unencryptedData length];
CCCryptorStatus ccStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, 0, key, kCCKeySizeAES128, iv, [encryptedData bytes], [encryptedData length], unencryptedData, [encryptedData length], &unencryptedLength);
NSString *output = [[NSString alloc] initWithBytes:unencryptedData length:unencryptedLength encoding:NSUTF8StringEncoding];
if (ccStatus == kCCSuccess) risultato.text = @"SUCCESS";
else if (ccStatus == kCCParamError) risultato.text = @"BAD PARAM";
else if (ccStatus == kCCBufferTooSmall) risultato.text = @"BUFFER TOO SMALL";
else if (ccStatus == kCCMemoryFailure) risultato.text = @"MEMORY FAILURE";
else if (ccStatus == kCCAlignmentError) risultato.text = @"ALIGNMENT";
else if (ccStatus == kCCDecodeError) risultato.text = @"DECODE ERROR";
else if (ccStatus == kCCUnimplemented) risultato.text = @"UNIMPLEMENTED";
EDIT2: this function return BAD PARAM because haven't the right buffer size where allocate decrypted data. I edit the function in this working way:
EDIT2：这个函数返回 BAD PARAM 因为没有正确的缓冲区大小来分配解密数据。我以这种工作方式编辑函数：
NSData *encryptedData = [response dataUsingEncoding: NSASCIIStringEncoding];
const void *key = @"32charlength;
uint8_t *iv = @"16charlength";
char buffer[4*4096];
memset(buffer, 'CCCryptorStatus
CCCrypt(CCOperation op, CCAlgorithm alg, CCOptions options, const void *key, size_t keyLength,
const void *iv, const void *dataIn, size_t dataInLength, void *dataOut, size_t dataOutAvailable,
size_t *dataOutMoved);
', sizeof(buffer));
size_t size = sizeof(buffer);
CCCryptorStatus ccStatus = CCCrypt(kCCDecrypt,
kCCAlgorithmAES128,
0,
key,
kCCKeySizeAES128,
iv,
[encryptedData bytes],
[encryptedData length],
buffer,
sizeof(buffer),
&size);
This function working for me.. thanks so much.
这个功能对我有用..非常感谢。
EDIT 23 MARCH------
编辑 3 月 23 日------
Now the system work form me with 16 byte key size. Now i have a question, what i can do to implement 32 byte key size ? thanks so much.
现在系统以 16 字节的密钥大小工作。现在我有一个问题，我可以做些什么来实现 32 字节的密钥大小？非常感谢。
采纳答案by Tark
This is possible using the CCCryptorfunctions included in the <CommonCrypto/CommonCryptor.h>header. Check man CCCryptorfor the gory details, in your case it sounds like you can use a single call to CCCrypt()to decode the received data:
这可以使用标题中CCCryptor包含的函数来实现<CommonCrypto/CommonCryptor.h>。检查man CCCryptor血腥细节，在您的情况下，听起来您可以使用单个调用CCCrypt()来解码接收到的数据：
char * key = "shouldbe16chars.";
NSUInteger dataLength = [encryptedData length];
uint8_t unencryptedData[dataLength + kCCKeySizeAES128];
size_t unencryptedLength;
CCCrypt(kCCDecrypt, kCCAlgorithmAES128, 0, key, kCCKeySizeAES128, NULL, [encryptedData bytes], dataLength, unencryptedData, dataLength, &unencryptedLength);
NSString *output = [[NSString alloc] initWithBytes:unencryptedData length:unencryptedLength encoding:NSUTF8StringEncoding];
Assuming you have the data to be decrypted in NSData *encryptedDatayou could try something like:
假设您有要解密的数据，NSData *encryptedData您可以尝试以下操作：
This is untested, make sure you check the return value of CCCryptfor errors. Check the header file for details, it is well documented.
这是未经测试的，请确保检查CCCrypt错误的返回值。检查头文件以获取详细信息，它有很好的文档记录。
