前几天做项目的时候遇到了3DES的解密数据，KEY是服务端返回的。在网上查了好多篇文章，发现IOS中3DES的KEY必须是24位的，而服务端传过来的KEY是32个字节的，那怎么办呢？还有偏移量又该怎么办呢？研究了好久，也看了很多大牛的文章，现在我就借花献佛，稍稍总结一下。demo最后给出。
主要的就是要组装解密KEY（并不需要GTMBase64），其次是偏移量要传nil 不多说直接看代码吧。
+ (NSString *)threeDESEncrypt:(NSString *)plainText withKey:(NSString *)key{
//16进制字符串转为 data数据
NSData *data = [self hexToBytes:key];
//组装解密key取前16个字节然后再次取前8个字节组成key
uint8_t *git = (uint8_t *)[data bytes];
uint8_t keyByte[24];
for (int i=0; i<16; i++) {
keyByte[i] = git[i];
}
for (int i=0; i<8; i++) {
keyByte[16+i] = git[i];
}
NSData *EncryptData = [self hexToBytes:plainText];
size_t plainTextBufferSize = [EncryptData length];
const void *vplainText = [EncryptData 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);
const void *vkey = (const void *) keyByte;
ccStatus =CCCrypt(kCCEncrypt,
kCCAlgorithm3DES,
kCCOptionECBMode,
vkey,
kCCKeySize3DES,
nil, //偏移量 直接传nil 不能传@“”
vplainText,
plainTextBufferSize,
(void *)bufferPtr,
bufferPtrSize,
&movedBytes);
NSData *dataresult = [NSData dataWithBytes:(const void *)bufferPtr
length:(NSUInteger)movedBytes];
NSString *result = [self hexStringFromData:dataresult];
return [result uppercaseString];
}
+ (NSString *)threeDESDecrypt:(NSString *)plainText withKey:(NSString *)key{
//16进制字符串转为 data数据
NSData *data = [self hexToBytes:key];
//组装解密key取前16个字节然后再次取前8个字节组成key
uint8_t *git = (uint8_t *)[data bytes];
uint8_t keyByte[24];
for (int i=0; i<16; i++) {
keyByte[i] = git[i];
}
for (int i=0; i<8; i++) {
keyByte[16+i] = git[i];
}
NSData *EncryptData = [self hexToBytes:plainText];
size_t plainTextBufferSize = [EncryptData length];
const void *vplainText = [EncryptData 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);
const void *vkey = (const void *) keyByte;
ccStatus =CCCrypt(kCCDecrypt,
kCCAlgorithm3DES,
kCCOptionECBMode,
vkey,
kCCKeySize3DES,
nil,
vplainText,
plainTextBufferSize,
(void *)bufferPtr,
bufferPtrSize,
&movedBytes);
NSData *dataresult = [NSData dataWithBytes:(const void *)bufferPtr
length:(NSUInteger)movedBytes];
NSString *result = [self hexStringFromData:dataresult];
return [result uppercaseString];
}
//其中用到的两个方法如下
/**
* 十六 进制字符串转换为 data
* 24211D3498FF62AF --> <24211D34 98FF62AF>
*
* @param str 要转换的字符串
*
* @return 转换后的数据
*/
+(NSData*)hexToBytes:(NSString *)str{
NSMutableData* data = [NSMutableData data];
int idx;
for (idx = 0; idx+2 <= str.length; idx+=2) {
NSRange range = NSMakeRange(idx,2);
NSString* hexStr = [str substringWithRange:range];
NSScanner* scanner = [NSScanner scannerWithString:hexStr];
unsigned int intValue;
[scanner scanHexInt:&intValue];
[data appendBytes:&intValue length:1];
}
return data;
}
/**
* data 转换为十六进制字符串
* <24211D34 98FF62AF> --> 24211D3498FF62AF
*
* @param data 要转换的data
*
* @return 转换后的字符串
*/
+ (NSString *)hexStringFromData:(NSData *)data{
NSMutableString *str = [NSMutableString string];
Byte *byte = (Byte *)[data bytes];
for (int i =0; i<[data length]; i++) {
// byte+i为指针
[str appendString:[self stringFromByte:*(byte+i)]];
}
return str;
}
+ (NSString *)stringFromByte:(Byte)byteVal
{
NSMutableString *str = [NSMutableString string];
//取高四位
Byte byte1 = byteVal>>4;
//取低四位
Byte byte2 = byteVal & 0xf;
//拼接16进制字符串
[str appendFormat:@"%x",byte1];
[str appendFormat:@"%x",byte2];
return str;
}
demo: https://github.com/shadowKnight0/WYDEncrypt
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