ios - 使用 iv 的 AES128 CTR 加密

Question

我想用 iv 和 key 实现 AES128 CTR。我正在寻找如何以最佳方式做到这一点而不是重新发明轮子的任何建议。

我为这个 RNCryptor 找到了很好的库, 但看起来那里不支持此 aes。

我也测试了this方法，但看起来这不是点击率。

编辑

---

我使用了来自@zaph 的 zpproach

NSData *result = [NSData cryptData:dataStr
                         operation:kCCEncrypt
                              mode:kCCModeCTR
                         algorithm:kCCAlgorithmAES128
                           padding:ccNoPadding
                         keyLength:kCCKeySizeAES128
                                iv:ivHex
                               key:keyHex
                             error:&error];

但收到 CCCryptorCreate 状态:-4305

刚刚在资源中找到

@constant kCCUnimplemented 函数未针对当前算法实现。

Link

Answer 1

您需要使用 CommonCrypto 但不是一次性 CCCrypt 版本，而是完整的 CCCryptorCreateWithMode、CCCryptorUpdate、CCCryptorFinal 和 CCCryptorRelease 模式为 kCCModeCTR 版本。

这是我的示例代码，它可能不适合您的需求，您必须决定柜台 (IV) 表格。

#import <CommonCrypto/CommonCrypto.h>

+ (NSData *)cryptData:(NSData *)dataIn
            operation:(CCOperation)operation  // kCC Encrypt, Decrypt
                 mode:(CCMode)mode            // kCCMode ECB, CBC, CFB, CTR, OFB, RC4, CFB8
            algorithm:(CCAlgorithm)algorithm  // CCAlgorithm AES DES, 3DES, CAST, RC4, RC2, Blowfish
              padding:(CCPadding)padding      // cc NoPadding, PKCS7Padding
            keyLength:(size_t)keyLength       // kCCKeySizeAES 128, 192, 256
                   iv:(NSData *)iv            // CBC, CFB, CFB8, OFB, CTR
                  key:(NSData *)key
                error:(NSError **)error
{
    if (key.length != keyLength) {
        NSLog(@"CCCryptorArgument key.length: %lu != keyLength: %zu", (unsigned long)key.length, keyLength);
        if (error) {
            *error = [NSError errorWithDomain:@"kArgumentError key length" code:key.length userInfo:nil];
        }
        return nil;
    }

    size_t dataOutMoved = 0;
    size_t dataOutMovedTotal = 0;
    CCCryptorStatus ccStatus = 0;
    CCCryptorRef cryptor = NULL;

    ccStatus = CCCryptorCreateWithMode(operation, mode, algorithm,
                                       padding,
                                       iv.bytes, key.bytes,
                                       keyLength,
                                       NULL, 0, 0, // tweak XTS mode, numRounds
                                       kCCModeOptionCTR_BE, // CCModeOptions
                                       &cryptor);

    if (cryptor == 0 || ccStatus != kCCSuccess) {
        NSLog(@"CCCryptorCreate status: %d", ccStatus);
        if (error) {
            *error = [NSError errorWithDomain:@"kCreateError" code:ccStatus userInfo:nil];
        }
        CCCryptorRelease(cryptor);
        return nil;
    }

    size_t dataOutLength = CCCryptorGetOutputLength(cryptor, dataIn.length, true);
    NSMutableData *dataOut = [NSMutableData dataWithLength:dataOutLength];
    char *dataOutPointer = (char *)dataOut.mutableBytes;

    ccStatus = CCCryptorUpdate(cryptor,
                               dataIn.bytes, dataIn.length,
                               dataOutPointer, dataOutLength,
                               &dataOutMoved);
    dataOutMovedTotal += dataOutMoved;

    if (ccStatus != kCCSuccess) {
        NSLog(@"CCCryptorUpdate status: %d", ccStatus);
        if (error) {
            *error = [NSError errorWithDomain:@"kUpdateError" code:ccStatus userInfo:nil];
        }
        CCCryptorRelease(cryptor);
        return nil;
    }

    ccStatus = CCCryptorFinal(cryptor,
                              dataOutPointer + dataOutMoved, dataOutLength - dataOutMoved,
                              &dataOutMoved);
    if (ccStatus != kCCSuccess) {
        NSLog(@"CCCryptorFinal status: %d", ccStatus);
        if (error) {
            *error = [NSError errorWithDomain:@"kFinalError" code:ccStatus userInfo:nil];
        }
        CCCryptorRelease(cryptor);
        return nil;
    }

    CCCryptorRelease(cryptor);

    dataOutMovedTotal += dataOutMoved;
    dataOut.length = dataOutMovedTotal;

    return dataOut;
}

示例调用:

NSData *dataIn  = [@"DataInDataInData" dataUsingEncoding: NSUTF8StringEncoding];
NSData *key     = [@"KeyKeyKeyKeyKeyK" dataUsingEncoding: NSUTF8StringEncoding];
NSData *counter = [@"CounterCounterCo" dataUsingEncoding: NSUTF8StringEncoding];
NSError *error;
NSData *encrpted = [Crypto
                    cryptData:dataIn
                    operation:kCCEncrypt
                    mode:kCCModeCTR
                    algorithm:kCCAlgorithmAES
                    padding:ccNoPadding
                    keyLength:kCCKeySizeAES128
                    iv:counter
                    key:key
                    error:&error];
NSLog(@"encrypted: %@", encrpted);

输出:加密:064e8073 76973eba 3192474f 9831db34