iOS URL加解密

URL加解密

背景介绍

• iOS 下URL加解密，项目使用AFNetworking
• 虽然是使用HTTPS，但是从安全方面考虑，在很多情况下还是需要对url的参数进行加密的。
• 接口如 https://192.160.0.123:92/frame/webInteface.do?(method=addNew&uid=123&pass=131)
• 不管是get请求还是post请求，都可以对后边的参数进行加密
• get请求比较简单，这里直接说post请求吧

加密方式

• 加密：首先对字符串记性AES128加密，然后进行base64加密（主要是为了去除特殊字符）
• 解密：先base64解密，然后在AES128解密即可还原数据
• 其中base64加解密使用 GTMBase64添加两个方法

+ (NSString*)encodeBase64Data:(NSData *)data {
    data = [GTMBase64 encodeData:data];
    NSString *base64String = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    return base64String;
}

+ (NSData*)decodeBase64String:(NSString * )input {
    NSData *data = [input dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
    data = [GTMBase64 decodeData:data];
    return data;
}

AES128使用系统CommonCrypto/CommonCryptor.h实现 //用于AES

添加NSData分类，增加两个方法

#pragma mark - AES128位加解密
- (NSData *)AES128EncryptWithKey:(NSString *)key {

    char keyPtr[kCCKeySizeAES128 + 1];
    memset(keyPtr, 0, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    NSUInteger dataLength = [self length];

    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);

    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                          kCCAlgorithmAES,
                                          kCCOptionPKCS7Padding|kCCOptionECBMode,
                                          keyPtr,
                                          kCCBlockSizeAES128,
                                          NULL /* initialization vector (optional) */,
                                          [self bytes],
                                          dataLength, /* input */
                                          buffer,
                                          bufferSize, /* output */
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        //the returned NSData takes ownership of the buffer and will free it on deallocation
        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
    }

    free(buffer); //free the buffer;
    return nil;
}

- (NSData *)AES128DecryptWithKey:(NSString *)key {
    // 'key' should be 32 bytes for AES256, will be null-padded otherwise
    char keyPtr[kCCKeySizeAES128+1]; // room for terminator (unused)
    bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)

    // fetch key data
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    NSUInteger dataLength = [self length];

    //See the doc: For block ciphers, the output size will always be less than or
    //equal to the input size plus the size of one block.
    //That's why we need to add the size of one block here
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);

    size_t numBytesDecrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                          kCCAlgorithmAES128,
                                          kCCOptionPKCS7Padding|kCCOptionECBMode,
                                          keyPtr,
                                          kCCBlockSizeAES128,
                                          NULL /* initialization vector (optional) */,
                                          [self bytes],
                                          dataLength, /* input */
                                          buffer,
                                          bufferSize, /* output */
                                          &numBytesDecrypted);

    if (cryptStatus == kCCSuccess) {
        //the returned NSData takes ownership of the buffer and will free it on deallocation
        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
    }

    free(buffer); //free the buffer;
    return nil;
}

直奔主题

• AFNetworking 的post请求如下

- (AFHTTPRequestOperation *)POST:(NSString *)URLString
                      parameters:(id)parameters
       constructingBodyWithBlock:(void (^)(id <AFMultipartFormData> formData))block
                         success:(void (^)(AFHTTPRequestOperation *operation, id responseObject))success
                         failure:(void (^)(AFHTTPRequestOperation *operation, NSError *error))failure

• 其中URLString可以作为最基础的，不需要加密
  
  parameters 就是我们需要加密的地方，这是一个字典,因为AFN会对这个parameters进行解析，所以对这个参数集合进行一次包装，拼接成一个字符串。然后对字符串进行加密。

原来的代码是这样请求数据的

NSMutableDictionary *para = [NSMutableDictionary dictionary];
para[@"method"] = @"securityAdd";
para[@"userId"] = userId;
para[@"userPsw"] = userPsw;
para[@"content"] = @"ddddd123891237";

      NSString *url = [NSString stringWithFormat:@"https://%@:82/frame/webInteface.do?", NHBaseURL];
AFHTTPRequestOperation *operation = [NetWorkInst POST:url parameters:dict constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
} success:^(AFHTTPRequestOperation *operation, id responseObject) {

}];

加密后代码是这样的

NSMutableDictionary *para = [NSMutableDictionary dictionary];
para[@"method"] = @"securityAdd";
para[@"userId"] = userId;
para[@"userPsw"] = userPsw;
para[@"content"] = @"ddddd123891237";

// 开始加密,格式化数据****************************
NSString *str = [NSString stringWithFormat:@"'method':'securityAdd','userId':'%@','userPsw':'%@','content':'%@'",userId,userPsw,content];
NSLog(@"原始数据：%@",str);
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
NSData *aaa = [data AES128EncryptWithKey:@"song.com"]; // aes加密
NSLog(@"加密AES128后：%@",aaa);
NSString *bbb = [PublicMethod encodeBase64Data:aaa];//base64加密
NSLog(@"base64加密后：%@",bbb);

NSMutableDictionary *dict = [NSMutableDictionary dictionary];
dict[@"info"] = bbb;

// 开始解密****************************
NSData *da = [PublicMethod decodeBase64String:bbb]; //base64解密
NSString *ccc = [[NSString alloc] initWithData:da encoding:NSUTF8StringEncoding];
NSLog(@"base64解密后：%@",ccc);
NSData *ddd = [da AES128DecryptWithKey:@"song.com"];// aes解密
NSString *eee = [[NSString alloc] initWithData:ddd encoding:NSUTF8StringEncoding];
NSLog(@"解密AES128后：%@",eee);

NSString *url = [NSString stringWithFormat:@"https://%@:82/frame/webInteface.do?", NHBaseURL];
AFHTTPRequestOperation *operation = [NetWorkInst POST:url parameters:dict constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
} success:^(AFHTTPRequestOperation *operation, id responseObject) {

}];

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