(PureBasic) AES 256-bit CBC using PBKDF2 Generated Secret Key

See more Encryption Examples

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;
    }

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkCrypt2.pb"

Procedure ChilkatExample()

    ; This example requires the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

    crypt.i = CkCrypt2::ckCreate()
    If crypt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    password.s = "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.)
    saltHex.s = "0102030405060708"

    ; Generate the 256-bit (32-byte) AES secret key we'll use to decrypt.
    iterationCount.i = 65536
    outputKeyBitLen.i = 256
    secretKeyHex.s = CkCrypt2::ckPbkdf2(crypt,password,"utf-8","sha256",saltHex,iterationCount,outputKeyBitLen,"hex")

    ; Setup for 256-bit AES CBC decryption.
    CkCrypt2::setCkCryptAlgorithm(crypt, "aes")
    CkCrypt2::setCkKeyLength(crypt, 256)
    CkCrypt2::setCkCipherMode(crypt, "cbc")
    CkCrypt2::setCkPaddingScheme(crypt, 0)

    ; The IV for AES is 16 bytes.
    iv.s = "000102030405060708090A0B0C0D0E0F"
    CkCrypt2::ckSetEncodedIV(crypt,iv,"hex")

    ; Set the secret key for 256-bit AES.
    CkCrypt2::ckSetEncodedKey(crypt,secretKeyHex,"hex")

    ; AES decrypt
    ; assume our string to decrypt is base64
    strToDecrypt.s = "...."
    CkCrypt2::setCkEncodingMode(crypt, "base64")
    decryptedStr.s = CkCrypt2::ckDecryptStringENC(crypt,strToDecrypt)

    Debug decryptedStr


    CkCrypt2::ckDispose(crypt)


    ProcedureReturn
EndProcedure