iOS开发－DES加密解密算法。

今天我们来把DES加解密的算法，整理保存一下。为了与安卓、java、C #等等一致。而且我们用到的是系统自带的加解密库。并未使用目前流行的GTMBase64。那么我们现在直接把代码粘贴进来吧。

一、使用DES加密方法

//加密
+(NSString *) encryptUseDES2:(NSString *)plainText key:(NSString *)key{
    NSString *ciphertext = nil;
    const char *textBytes = [plainText UTF8String];
    size_t dataLength = [plainText length];
    //==================
    
    uint8_t *bufferPtr = NULL;
    size_t bufferPtrSize = 0;
    size_t movedBytes = 0;
    
    bufferPtrSize = (dataLength + kCCBlockSizeDES) & ~(kCCBlockSizeDES - 1);
    bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
    memset((void *)bufferPtr, 0x0, bufferPtrSize);
    
    
    NSString *testString = key;
    NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];
    Byte *iv = (Byte *)[testData bytes];
    
    
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmDES,
                                          kCCOptionPKCS7Padding,
                                          [key UTF8String], kCCKeySizeDES,
                                          iv,
                                          textBytes, dataLength,
                                          (void *)bufferPtr, bufferPtrSize,
                                          &movedBytes);
    if (cryptStatus == kCCSuccess) {
        
        ciphertext= [XuDes parseByte2HexString:bufferPtr :(int)movedBytes];

    }
    ciphertext=[ciphertext uppercaseString];//字符变大写
    
    return ciphertext ;
}

二、使用DES进行解密计算

//解密
+(NSString *)decryptUseDES:(NSString *)cipherText key:(NSString *)key
{
    
    NSData* cipherData = [XuDes convertHexStrToData:[cipherText lowercaseString]];
    NSLog(@"++++++++///%@",cipherData);
    unsigned char buffer[1024];
    memset(buffer, 0, sizeof(char));
    size_t numBytesDecrypted = 0;
    NSString *testString = key;
    NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];
    Byte *iv = (Byte *)[testData bytes];
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                          kCCAlgorithmDES,
                                          kCCOptionPKCS7Padding,
                                          [key UTF8String],
                                          kCCKeySizeDES,
                                          iv,
                                          [cipherData bytes],
                                          [cipherData length],
                                          buffer,
                                          1024,
                                          &numBytesDecrypted);
    NSString* plainText = nil;
    if (cryptStatus == kCCSuccess) {
        NSData* data = [NSData dataWithBytes:buffer length:(NSUInteger)numBytesDecrypted];
        plainText = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    }
    return plainText;

}

加密解密中有两个方法调用，其实是为了16进制与data之间的转换。有些宝宝们的公司并未转换成16进制，而是需要跟base64共同加解密。方法适用，只需要将得出的plainText 的值转成base64即可。

加密时转成16进制

+(NSString *) parseByte2HexString:(Byte *) bytes  :(int)len{
    
    
    NSString *hexStr = @"";
    
    if(bytes)
    {
        for(int i=0;i<len;i++)
        {
            NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff]; ///16进制数
            if([newHexStr length]==1)
                hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
            else
            {
                hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
            }
            
            NSLog(@"%@",hexStr);
        }
    }
    
    return hexStr;
}

解密时转回data

+ (NSData *)convertHexStrToData:(NSString *)str {
    if (!str || [str length] == 0) {
        return nil;
    }
    
    NSMutableData *hexData = [[NSMutableData alloc] initWithCapacity:8];
    NSRange range;
    if ([str length] % 2 == 0) {
        range = NSMakeRange(0, 2);
    } else {
        range = NSMakeRange(0, 1);
    }
    for (NSInteger i = range.location; i < [str length]; i += 2) {
        unsigned int anInt;
        NSString *hexCharStr = [str substringWithRange:range];
        NSScanner *scanner = [[NSScanner alloc] initWithString:hexCharStr];
        
        [scanner scanHexInt:&anInt];
        NSData *entity = [[NSData alloc] initWithBytes:&anInt length:1];
        [hexData appendData:entity];
        
        range.location += range.length;
        range.length = 2;
    }
    
    NSLog(@"hexdata: %@", hexData);
    return hexData;
}

好了，总结整理到这里。有不懂的宝宝们，留言。看到会回复的。