(Unicode C++) AES 256-bit CBC using PBKDF2 Generated Secret Key

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First generates a 32-byte secret key using PBKDF2 (with HMAC-SHA256), and then uses the secret key to do 256-bit AES CBC mode decryption.

(Duplicates the following Java code)

public String decrypt(String strToDecrypt) {
        try  {
            // Read the initialization vector from the first bytes for the data
            byte [] rawData = Base64.getDecoder().decode(strToDecrypt);
            byte [] iv = new byte[Config.get().encryptionIVLength()];
            byte [] encryptedData = new byte[rawData.length - iv.length];
            System.arraycopy(rawData, 0, iv, 0, iv.length);
            System.arraycopy(rawData, iv.length, encryptedData, 0, encryptedData.length);
 
            IvParameterSpec ivspec = new IvParameterSpec(iv);
 
            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
            KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), salt.getBytes(), 65536, 256);
            SecretKey tmp = factory.generateSecret(spec);
            SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");
 
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
            cipher.init(Cipher.DECRYPT_MODE, secretKey, ivspec);
            return new String(cipher.doFinal(encryptedData));
        }
        catch (Exception e) {
            log.error("Could not decrypt the string.", e);
        }
        return null;
    }

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#include <CkCrypt2W.h>

void ChilkatSample(void)
    {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkCrypt2W crypt;

    const wchar_t *password = L"some arbitrary length password";
    // We have 8 bytes of salt encoded using hex.
    // (The salt can be any number of bytes, in any desired encoding such as base64, hex, etc.)
    const wchar_t *saltHex = L"0102030405060708";

    // Generate the 256-bit (32-byte) AES secret key we'll use to decrypt.
    int iterationCount = 65536;
    int outputKeyBitLen = 256;
    const wchar_t *secretKeyHex = crypt.pbkdf2(password,L"utf-8",L"sha256",saltHex,iterationCount,outputKeyBitLen,L"hex");

    // Setup for 256-bit AES CBC decryption.
    crypt.put_CryptAlgorithm(L"aes");
    crypt.put_KeyLength(256);
    crypt.put_CipherMode(L"cbc");
    crypt.put_PaddingScheme(0);

    // The IV for AES is 16 bytes.
    const wchar_t *iv = L"000102030405060708090A0B0C0D0E0F";
    crypt.SetEncodedIV(iv,L"hex");

    // Set the secret key for 256-bit AES.
    crypt.SetEncodedKey(secretKeyHex,L"hex");

    // AES decrypt
    // assume our string to decrypt is base64
    const wchar_t *strToDecrypt = L"....";
    crypt.put_EncodingMode(L"base64");
    const wchar_t *decryptedStr = crypt.decryptStringENC(strToDecrypt);

    wprintf(L"%s\n",decryptedStr);
    }