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(DataFlex) AES 256-bit CBC using PBKDF2 Generated Secret KeySee more Encryption ExamplesFirst 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;
}
Use ChilkatAx-win32.pkg Procedure Test Handle hoCrypt String sPassword String sSaltHex Integer iIterationCount Integer iOutputKeyBitLen String sSecretKeyHex String sIv String sStrToDecrypt String sDecryptedStr // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. Get Create (RefClass(cComChilkatCrypt2)) To hoCrypt If (Not(IsComObjectCreated(hoCrypt))) Begin Send CreateComObject of hoCrypt End Move "some arbitrary length password" To sPassword // 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.) Move "0102030405060708" To sSaltHex // Generate the 256-bit (32-byte) AES secret key we'll use to decrypt. Move 65536 To iIterationCount Move 256 To iOutputKeyBitLen Get ComPbkdf2 Of hoCrypt sPassword "utf-8" "sha256" sSaltHex iIterationCount iOutputKeyBitLen "hex" To sSecretKeyHex // Setup for 256-bit AES CBC decryption. Set ComCryptAlgorithm Of hoCrypt To "aes" Set ComKeyLength Of hoCrypt To 256 Set ComCipherMode Of hoCrypt To "cbc" Set ComPaddingScheme Of hoCrypt To 0 // The IV for AES is 16 bytes. Move "000102030405060708090A0B0C0D0E0F" To sIv Send ComSetEncodedIV To hoCrypt sIv "hex" // Set the secret key for 256-bit AES. Send ComSetEncodedKey To hoCrypt sSecretKeyHex "hex" // AES decrypt // assume our string to decrypt is base64 Move "...." To sStrToDecrypt Set ComEncodingMode Of hoCrypt To "base64" Get ComDecryptStringENC Of hoCrypt sStrToDecrypt To sDecryptedStr Showln sDecryptedStr End_Procedure |
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