iphone - 3des加密kCCAlignmentError错误

Question

我正在尝试加密 xml 字符串。加密完成后，解密加密的 d，我得到的字符串为 ALIGNMENT。
不明白是什么原因

(NSString*) doCipher:(NSString*)plainText:(CCOperation)encryptOrDecrypt {

const void *vplainText;
size_t plainTextBufferSize;

if (encryptOrDecrypt == kCCDecrypt)
{
    NSData *EncryptData = [NSData dataFromBase64String:plainText];
    plainTextBufferSize = [EncryptData length];
    vplainText = [EncryptData bytes];
}
else
{
    plainTextBufferSize = [plainText length];
    vplainText = (const void *) [plainText UTF8String];
}

CCCryptorStatus ccStatus;
uint8_t *bufferPtr = NULL;
size_t bufferPtrSize = 0;
size_t movedBytes = 0;
// uint8_t iv[kCCBlockSize3DES];

bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
memset((void *)bufferPtr, 0x0, bufferPtrSize);
// memset((void *) iv, 0x0, (size_t) sizeof(iv));

NSString *key = @"123456789012345678901234";
NSString *initVec = @"init Vec";
const void *vkey = (const void *) [key UTF8String];
const void *vinitVec = (const void *) [initVec UTF8String];

ccStatus = CCCrypt(encryptOrDecrypt,
                   kCCAlgorithm3DES,
                   kCCOptionPKCS7Padding,
                   vkey, //"123456789012345678901234", //key
                   kCCKeySize3DES,
                   vinitVec, //"init Vec", //iv,
                   vplainText, //"Your Name", //plainText,
                   plainTextBufferSize,
                   (void *)bufferPtr,
                   bufferPtrSize,
                   &movedBytes);
//if (ccStatus == kCCSuccess) NSLog(@"SUCCESS");
//else/
if (ccStatus == kCCParamError) return @"PARAM ERROR";
else if (ccStatus == kCCBufferTooSmall) return @"BUFFER TOO SMALL";
else if (ccStatus == kCCMemoryFailure) return @"MEMORY FAILURE";
else if (ccStatus == kCCAlignmentError) return @"ALIGNMENT";
else if (ccStatus == kCCDecodeError) return @"DECODE ERROR";
else if (ccStatus == kCCUnimplemented) return @"UNIMPLEMENTED";

NSString *result;

if (encryptOrDecrypt == kCCDecrypt)
{
    result = [ [NSString alloc] initWithData: [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes] encoding:NSASCIIStringEncoding];
}
else
{
    NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes];
    result = [myData base64EncodedString];
}    
return result;    
}

Answer 1

kCCAlignmentError 表示您传递的数据未正确填充(具体来说，包括填充在内的整个数据长度不是 block 大小的倍数)。最可能的原因是您在某个地方截断了加密数据，可能是在此例程之外。

您应该在每一步检查加密数据，并确保它始终是 block 大小(8 字节)的倍数。在检查长度之前，您需要进行 Base64 解码。