如何在iOS中解密DES加密字符串？

Question

I used PHP to encrypt a string with PKCS #7 padding in DES algorithm.

I want to know how to use CCCrypt in iOS to decrypt the DES encrypted string. Appreciate it if you could provide some sample codes to help me.

Thanks.

Answer 1

- (NSData *)encryptDESByKey:(NSData *)key data:(NSData *)data
{
size_t numBytesEncrypted = 0;
size_t bufferSize = data.length + kCCBlockSizeDES;
void *buffer = malloc(bufferSize);

CCCryptorStatus result = CCCrypt( kCCEncrypt, kCCAlgorithmDES, kCCOptionPKCS7Padding,
                                 key.bytes, kCCKeySizeDES,
                                 NULL,
                                 data.bytes, data.length,
                                 buffer, bufferSize,
                                 &numBytesEncrypted);
NSData *output = [NSData dataWithBytes:buffer length:numBytesEncrypted];
free(buffer);
if( result == kCCSuccess )
{
    NSLog(@"encoded str %@",[output base64EncodedStringWithOptions:0]);
    return output;
} else {
    NSLog(@"Failed DES encrypt...");
    return nil;
}
}
- (NSData *) decryptDESByKey:(NSData *)key data:(NSData *)data
{
size_t numBytesEncrypted = 0;

size_t bufferSize = data.length + kCCBlockSizeDES;
void *buffer_decrypt = malloc(bufferSize);
CCCryptorStatus result = CCCrypt( kCCDecrypt , kCCAlgorithmDES, kCCOptionPKCS7Padding,
                                 key.bytes, kCCKeySizeDES,
                                 NULL,
                                 data.bytes, data.length,
                                 buffer_decrypt, bufferSize,
                                 &numBytesEncrypted );

NSData *output = [NSData dataWithBytes:buffer_decrypt length:numBytesEncrypted];
free(buffer_decrypt);
if( result == kCCSuccess )
{
    NSString *decodedString = [[NSString alloc] initWithData:output encoding:NSUTF8StringEncoding];
    NSLog(@"decoded str %@",decodedString);
    return output;
} else {
    NSLog(@"Failed DES decrypt ...");
    return nil;
}
}

-- Then you can call method like

  [self decryptDESByKey:[@"qwertykey" dataUsingEncoding:NSUTF8StringEncoding] data:[self encryptDESByKey:[@"qwertykey" dataUsingEncoding:NSUTF8StringEncoding] data:["YOUR--INPUT__STRING" dataUsingEncoding:NSUTF8StringEncoding]]];

-- "qwertykey" is the secretkey supplied