iOS开发－DES加密解密算法

最新推荐文章于 2021-02-15 23:58:12 发布

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#DES加密

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本文介绍了一种在iOS平台上实现DES加密和解密的方法，包括如何将明文转化为密文，以及如何从密文中还原出原始数据。此外，还提供了十六进制字符串与NSData相互转换的具体实现。

前几天后台给了一个Java代码的加解密方式，让我这边直接用。我对应着Java上解密方法找到一些适合iOS的DES加解密算法，特总结一下

1、使用DES加密：

//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 ;
 }

2、使用DES解密

//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;
 }

//解密2
-(NSString*) decryptUseDES2:(NSString*)cipherText key:(NSString*)key {
    // 利用 GTMBase64 解碼 Base64 字串
//    NSData* cipherData = [GTMBase64 decodeData:[cipherText dataUsingEncoding:NSUTF8StringEncoding]];
    NSData* cipherData = [self convertHexStrToData:[cipherText lowercaseString]];
    size_t bufferSize = [cipherData length] + kCCBlockSizeDES & ~(kCCBlockSizeDES - 1);
    unsigned char buffer[bufferSize];
    memset(buffer, 0, sizeof(char));
    size_t numBytesDecrypted = 0;
    // IV 偏移量不需使用
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                          kCCAlgorithmDES,
                                          kCCOptionPKCS7Padding | kCCOptionECBMode,
                                          [key UTF8String],
                                          kCCKeySizeDES,
                                          nil,
                                          [cipherData bytes],
                                          [cipherData length],
                                          buffer,
                                          bufferSize,//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;

}