Question

我正在搜索AES加密的一些可可代码，我做了一些谷歌搜索。我发现这个非常有用的链接 - http://iphonedevelopment.blogspot.com/2009/02/strong-encryption-for-cocoa-cocoa-touch.html。所以我试了一下，但它对我不起作用。

任何人都可以向我建议一些有用的链接或源代码，它们可以帮助我在我的示例应用程序中实现它。

Answer 1

我使用NSData上的一个简单类别，它使用内置的CommonCrypto框架进行AES 256位加密。我在Mac上使用它，但它也适用于iPhone：

#import <CommonCrypto/CommonCryptor.h>
@implementation NSData (AESAdditions)
- (NSData*)AES256EncryptWithKey:(NSString*)key {
    // 'key' should be 32 bytes for AES256, will be null-padded otherwise
    char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused)
    bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)

    // fetch key data
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    NSUInteger dataLength = [self length];

    //See the doc: For block ciphers, the output size will always be less than or
    //equal to the input size plus the size of one block.
    //That's why we need to add the size of one block here
    size_t bufferSize           = dataLength + kCCBlockSizeAES128;
    void* buffer                = malloc(bufferSize);

    size_t numBytesEncrypted    = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
                                          keyPtr, kCCKeySizeAES256,
                                          NULL /* initialization vector (optional) */,
                                          [self bytes], dataLength, /* input */
                                          buffer, bufferSize, /* output */
                                          &numBytesEncrypted);

    if (cryptStatus == kCCSuccess)
    {
        //the returned NSData takes ownership of the buffer and will free it on deallocation
        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
    }

    free(buffer); //free the buffer;
    return nil;
}

- (NSData*)AES256DecryptWithKey:(NSString*)key {
    // 'key' should be 32 bytes for AES256, will be null-padded otherwise
    char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused)
    bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)

    // fetch key data
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    NSUInteger dataLength = [self length];

    //See the doc: For block ciphers, the output size will always be less than or
    //equal to the input size plus the size of one block.
    //That's why we need to add the size of one block here
    size_t bufferSize           = dataLength + kCCBlockSizeAES128;
    void* buffer                = malloc(bufferSize);

    size_t numBytesDecrypted    = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
                                          keyPtr, kCCKeySizeAES256,
                                          NULL /* initialization vector (optional) */,
                                          [self bytes], dataLength, /* input */
                                          buffer, bufferSize, /* output */
                                          &numBytesDecrypted);

    if (cryptStatus == kCCSuccess)
    {
        //the returned NSData takes ownership of the buffer and will free it on deallocation
        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
    }

    free(buffer); //free the buffer;
    return nil;
}
@end

Answer 2

在CommonCrypto框架中，iPhone上提供AES128加密。相关函数位于CommonCryptor.h标题中。

您可以像这样创建一个加密：

// Assume key and keylength exist
CCCryptorRef cryptor;
if(kCCSuccess != CCCryptorCreate(kCCEncrypt, kCCAlgorithmAES128, 0, key, keyLength, NULL, &cryptor))
  ; //handle error

// Repeatedly call CCCryptorUpdate to encrypt the data

CCCryptorRelease(cryptor);

似乎从问题和链接中寻找AES的示例实现。我不建议这样做 - 使用Apple的实现！

看起来http://pastie.org/297563.txt也可能对您有所帮助，但我还没有测试过它。

Answer 3

我找到的所有例子都不适合我，所以我改变了上面的解决方案。这个适用于我并使用Google-Lib for Base64：

+ (NSData *)AES256DecryptWithKey:(NSString *)key data:(NSData*)data encryptOrDecrypt:(CCOperation)encryptOrDecrypt {

    // 'key' should be 32 bytes for AES256, will be null-padded otherwise
    char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
    bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)

    // fetch key data
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    if (encryptOrDecrypt == kCCDecrypt)
    {
        data = [GTMBase64 decodeData:data];
    }

        NSUInteger dataLength = [data length];

    //See the doc: For block ciphers, the output size will always be less than or 
    //equal to the input size plus the size of one block.
    //That's why we need to add the size of one block here
    size_t bufferSize = dataLength + kCCBlockSizeAES128;

    void *buffer = malloc(bufferSize);

    size_t numBytesDecrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(encryptOrDecrypt,
                                          kCCAlgorithmAES128,
                                          kCCOptionPKCS7Padding,
                                          keyPtr,
                                          kCCKeySizeAES256,
                                          NULL /* initialization vector (optional) */,
                                          [data bytes], dataLength, /* input */
                                          buffer,       bufferSize, /* output */
                                          &numBytesDecrypted);

    if (cryptStatus != kCCSuccess){ 
        NSLog(@"ERROR WITH FILE ENCRYPTION / DECRYPTION");
        return nil;
    }

    NSData *result;

    if (encryptOrDecrypt == kCCDecrypt)
    {
        result = [NSData dataWithBytes:(const void *)buffer length:(NSUInteger)numBytesDecrypted];
    }
    else
    {
        NSData *myData = [NSData dataWithBytes:(const void *)buffer length:(NSUInteger)numBytesDecrypted];
        result = [GTMBase64 encodeData:myData];
    }

    free(buffer); //free the buffer;
    return result;
}

Answer 4

感谢伟大的类别扩展。我发现的一件事 - 当您使用CCCrypt的算法强于64位时，您需要符合BIS出口法规。有关详细信息，请参阅iTunes Connect常见问题。即使您使用Apple的inbuild加密api，您也需要获得BIS的批准。

之前有一个关于这个主题的讨论（在ssl用法的上下文中）：

Using SSL in an iPhone App - Export Compliance

最诚挚的问候克里斯

AES加密解密的任何可可源代码？

4 个答案: