iOS 以byte数组作为密钥的3des加密

最近做3des加密的时候，服务器返回的byte数组作为密钥，网上的方法都是以字符串作为密钥。先将字符串进行utf8编码，再转换成data，这样和直接用byte数组进行加密是有区别的，转换后的data字节数增加了一倍，这时候怎么办呢？

首先 对密钥字符串进行处理，把16进制字符串转换为byte数组（nadata）

- (NSData *) stringToHexData
{
int len = [self length] / 2;    // Target length
unsigned char *buf = malloc(len);
unsigned char *whole_byte = buf;
char byte_chars[3] = {'\0','\0','\0'};

int i;
for (i=0; i < [self length] / 2; i++) {
byte_chars[0] = [self characterAtIndex:i*2];
byte_chars[1] = [self characterAtIndex:i*2+1];
*whole_byte = strtol(byte_chars, NULL, 16);
whole_byte++;
}

NSData *data = [NSData dataWithBytes:buf length:len];
free( buf );
return data;
}

这样就得到了data的密钥，然后进行3des加密

+(NSString*)TripleDES:(NSString*)plainText  andCCOperation:(CCOperation )encryptOrDecrypt  anddata:(NSData*)data
{

const void *vplainText;
size_t plainTextBufferSize;

if (encryptOrDecrypt == kCCDecrypt)//解密
{
NSData *EncryptData = [GTMBase64 decodeData:[plainText dataUsingEncoding:NSUTF8StringEncoding]];
plainTextBufferSize = [EncryptData length];
vplainText = [EncryptData bytes];
}
else //加密
{
NSData* data = [plainText dataUsingEncoding:NSUTF8StringEncoding];
plainTextBufferSize = [data length];
vplainText = (const void *)[data bytes];
}

CCCryptorStatus ccStatus;
uint8_t *bufferPtr = NULL;
size_t bufferPtrSize = 0;
size_t movedBytes = 0;

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

//const void *vkey = (const void *)[DESKEY UTF8String];
const void *vkey = (const void *)[data bytes];

// NSString *initVec = @"init Vec";
//const void *vinitVec = (const void *) [initVec UTF8String];
//  Byte iv[] = {0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF};
ccStatus = CCCrypt(encryptOrDecrypt,
kCCAlgorithm3DES,
kCCOptionPKCS7Padding | kCCOptionECBMode,
vkey,
kCCKeySize3DES,
nil,
vplainText,
plainTextBufferSize,
(void *)bufferPtr,
bufferPtrSize,
&movedBytes);
NSString *result;

if (encryptOrDecrypt == kCCDecrypt)
{
result = [[NSString alloc] initWithData:[NSData dataWithBytes:(const void *)bufferPtr
length:(NSUInteger)movedBytes]
encoding:NSUTF8StringEncoding];
}
else
{
NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes];
result = [GTMBase64 stringByEncodingData:myData];
}

return result;
}

ok,这样就可以得到加密后的结果了