相当于ios的spongycastle加密

Question

这让我很难过 - 以下代码使用SpongyCastle的Android加密/解密 - 我正在尝试为iOS实现跨平台加密/解密.

下面的代码(来自Android)使用PKCS7Padding处理AES 128bit CBC,使用提供的salt和密码,salt存储在mysql数据库中,密码由最终用户提供,以下代码改编自此kelhoer回答.

我之所以使用AES128bit是因为AES256在iOS 4+中不可用,它是在iOS5 +中引入的,并且不得不使用脚趾openssl来生成派生密钥和初始化矢量(iv),因为学到苹果公司拒绝它是很冒险的与openssl库静态链接的应用程序.

由于该平台基于iOS 4.2+,因此使用捆绑和静态链接openssl库似乎过度杀死并且最好使用CommonCryptor库.

这是使用Spongycastle代码的Android版本:

private static void encrypt(InputStream fin, 
    OutputStream fout, 
    String password, 
    byte[] bSalt) {
    try {
        PKCS12ParametersGenerator pGen = new PKCS12ParametersGenerator(
            new SHA256Digest()
            );
        char[] passwordChars = password.toCharArray();
        final byte[] pkcs12PasswordBytes = 
            PBEParametersGenerator.PKCS12PasswordToBytes(passwordChars);
        pGen.init(pkcs12PasswordBytes, bSalt, ITERATIONS);
        CBCBlockCipher aesCBC = new CBCBlockCipher(new AESEngine());
        ParametersWithIV aesCBCParams = 
            (ParametersWithIV) pGen.generateDerivedParameters(128, 128);
        aesCBC.init(true, aesCBCParams);
        PaddedBufferedBlockCipher aesCipher = 
            new PaddedBufferedBlockCipher(aesCBC, new PKCS7Padding());
        aesCipher.init(true, aesCBCParams);
        byte[] buf = new byte[BUF_SIZE];
        // Read in the decrypted bytes and write the cleartext to out
        int numRead = 0;
        while ((numRead = fin.read(buf)) >= 0) {
            if (numRead == 1024) {
                byte[] plainTemp = new byte[
                    aesCipher.getUpdateOutputSize(numRead)];
                int offset = 
                    aesCipher.processBytes(buf, 0, numRead, plainTemp, 0);
                final byte[] plain = new byte[offset];
                System.arraycopy(plainTemp, 0, plain, 0, plain.length);
                fout.write(plain, 0, plain.length);
            } else {
                byte[] plainTemp = new byte[aesCipher.getOutputSize(numRead)];
                int offset = 
                    aesCipher.processBytes(buf, 0, numRead, plainTemp, 0);
                int last = aesCipher.doFinal(plainTemp, offset);
                final byte[] plain = new byte[offset + last];
                System.arraycopy(plainTemp, 0, plain, 0, plain.length);
                fout.write(plain, 0, plain.length);
            }
        }
        fout.close();
        fin.close();
    } catch (Exception e) {
        e.printStackTrace();
    }

}

private static void decrypt(InputStream fin, 
    OutputStream fout, 
    String password, 
    byte[] bSalt) {
    try {
        PKCS12ParametersGenerator pGen = new PKCS12ParametersGenerator(
            new SHA256Digest()
            );
        char[] passwordChars = password.toCharArray();
        final byte[] pkcs12PasswordBytes = 
            PBEParametersGenerator.PKCS12PasswordToBytes(passwordChars);
        pGen.init(pkcs12PasswordBytes, bSalt, ITERATIONS);
        CBCBlockCipher aesCBC = new CBCBlockCipher(new AESEngine());
        ParametersWithIV aesCBCParams = 
            (ParametersWithIV) pGen.generateDerivedParameters(128, 128);
        aesCBC.init(false, aesCBCParams);
        PaddedBufferedBlockCipher aesCipher = 
            new PaddedBufferedBlockCipher(aesCBC, new PKCS7Padding());
        aesCipher.init(false, aesCBCParams);
        byte[] buf = new byte[BUF_SIZE];
        // Read in the decrypted bytes and write the cleartext to out
        int numRead = 0;
        while ((numRead = fin.read(buf)) >= 0) {
            if (numRead == 1024) {
                byte[] plainTemp = new byte[
                    aesCipher.getUpdateOutputSize(numRead)];
                int offset = 
                    aesCipher.processBytes(buf, 0, numRead, plainTemp, 0);
                // int last = aesCipher.doFinal(plainTemp, offset);
                final byte[] plain = new byte[offset];
                System.arraycopy(plainTemp, 0, plain, 0, plain.length);
                fout.write(plain, 0, plain.length);
            } else {
                byte[] plainTemp = new byte[
                    aesCipher.getOutputSize(numRead)];
                int offset = 
                    aesCipher.processBytes(buf, 0, numRead, plainTemp, 0);
                int last = aesCipher.doFinal(plainTemp, offset);
                final byte[] plain = new byte[offset + last];
                System.arraycopy(plainTemp, 0, plain, 0, plain.length);
                fout.write(plain, 0, plain.length);
            }
        }
        fout.close();
        fin.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

但是在iOS 4.2(使用XCode)下我无法弄清楚如何做等效的,

这就是我在Objective C下尝试过的,其目标是解密来自Android端的数据,存储在mysql数据库中,以测试它:

+(NSData*) decrypt:(NSData*)cipherData 
    userPassword:(NSString*)argPassword 
    genSalt:(NSData*)argPtrSalt{

    size_t szPlainBufLen = cipherData.length + (kCCBlockSizeAES128);
    uint8_t *ptrPlainBuf = malloc(szPlainBufLen);
    //
    const unsigned char *ptrPasswd = 
        (const unsigned char*)[argPassword 
            cStringUsingEncoding:NSASCIIStringEncoding];
    int ptrPasswdLen = strlen(ptrPasswd);
    //
    NSString *ptrSaltStr = [[NSString alloc]
        initWithData:argPtrSalt 
        encoding:NSASCIIStringEncoding];

    const unsigned char *ptrSalt = 
        (const unsigned char *)[ptrSaltStr UTF8String];
    NSString *ptrCipherStr = 
        [[NSString alloc]initWithData:cipherData 
            encoding:NSASCIIStringEncoding];
    unsigned char *ptrCipher = (unsigned char *)[ptrCipherStr UTF8String];
    unsigned char key[kCCKeySizeAES128];
    unsigned char iv[kCCKeySizeAES128];
    //
    //int     EVP_BytesToKey(const EVP_CIPHER *type,const EVP_MD *md,
    //const unsigned char *salt, const unsigned char *data,
    //int datal, int count, unsigned char *key,unsigned char *iv);
    int i = EVP_BytesToKey(EVP_aes_128_cbc(), 
                       EVP_sha256(), 
                       ptrSalt, 
                       ptrPasswd, 
                       ptrPasswdLen, 
                       PBKDF2_ITERATIONS, 
                       key, 
                       iv);
    NSAssert(i == kCCKeySizeAES128, 
        @"Unable to generate key for AES");
    //
    size_t cipherLen = [cipherData length];
    size_t outlength = 0;
    //
    CCCryptorStatus resultCCStatus = CCCrypt(kCCDecrypt,
                                             kCCAlgorithmAES128,
                                             kCCOptionPKCS7Padding,
                                             key,
                                             kCCBlockSizeAES128,
                                             iv,
                                             ptrCipher,
                                             cipherLen,
                                             ptrPlainBuf,
                                             szPlainBufLen,
                                             &outlength);
    NSAssert(resultCCStatus == kCCSuccess, 
        @"Unable to perform PBE AES128bit decryption: %d", errno);
    NSData *ns_dta_PlainData = nil;

    if (resultCCStatus == kCCSuccess){
        ns_dta_PlainData = 
        [NSData dataWithBytesNoCopy:ptrPlainBuf length:outlength];
    }else{
        return nil;
    }
    return ns_dta_PlainData;
}

已经提供的数据和用户的密码,并得到一个返回代码CCCrypt为-4304这表明尚未成功,坏的解码.

我原以为编码方案可能会抛弃CommonCryptor的解密路由,因此转换为啰嗦的方式NSASCIIStringEncoding.

Salt与密码数据一起存储,长度为32字节.

考虑到密码学方面的问题,我在这方面缺少什么.

Answer 1

是的，我不得不放弃Android端的加密算法，这对我来说是一个挑战，找到一个跨平台兼容的算法。

我读了很多关于Rob Napier 的 RNCryptor 的文章，在谷歌搜索了 Android 的等效版本后，我发现了JNCryptor，我冒险在 iOS 端使用了 RNCryptor 。

在github上分叉 JNCryptor 代码，以添加增强功能，能够指定自定义设置，并为旧版本的 Android 使用 SpongyCastle。从那时起，两个平台都能够互换加密/解密。

我增强 JNCryptor 的原因是 PKDBF2 函数的迭代计数非常高 - 10,000 并且是默认值（因为代码将在旧手机上运行 - 它卡住了 - 如果你有双核/四核，那就太棒了！），并且需要重写迭代计数以使其更“可承受” - 1,000。RNCryptor 可以使用自定义设置。

感谢 Rob Napier 和 Duncan Jones 的工作！