Java

Encrypt File in Chunks using AES CBC

See more Encryption Examples

Demonstrates how to use the FirstChunk/LastChunk properties to encrypt a file chunk-by-chunk. Chilkat2 Java

import com.chilkatsoft.chilkat2.BinData;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Crypt2;
import com.chilkatsoft.chilkat2.FileAccess;

public class ChilkatExample {

    public static void main(String[] args) {
        // This example assumes the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        Crypt2 crypt = new Crypt2();

        crypt.setCryptAlgorithm("aes");
        crypt.setCipherMode("cbc");
        crypt.setKeyLength(256);

        crypt.setEncodedKey("000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F", "hex");
        crypt.setEncodedIV("000102030405060708090A0B0C0D0E0F", "hex");

        String fileToEncrypt = "qa_data/hamlet.xml";
        FileAccess facIn = new FileAccess();
        try {
            facIn.openForRead(fileToEncrypt);
        } catch (ChilkatException e) {
            System.out.println("Failed to open file that is to be encrytped.");
            return;
        }

        String outputEncryptedFile = "c:/temp/qa_output/hamlet.enc";
        FileAccess facOutEnc = new FileAccess();
        try {
            facOutEnc.openForWrite(outputEncryptedFile);
        } catch (ChilkatException e) {
            System.out.println("Failed to encrypted output file.");
            return;
        }

        // Let's encrypt in 10000 byte chunks.
        int chunkSize = 10000;
        int numChunks = facIn.getNumBlocks(chunkSize);

        crypt.setFirstChunk(true);
        crypt.setLastChunk(false);

        BinData bd = new BinData();

        int i = 0;
        while (i < numChunks) {
            i = i + 1;
            if (i == numChunks) {
                crypt.setLastChunk(true);
            }

            // Read the next chunk from the file.
            // The last chunk will be whatever amount remains in the file..
            bd.clear();
            facIn.fileReadBd(chunkSize, bd);

            // Encrypt.
            crypt.encryptBd(bd);

            // Write the encrypted chunk to the output file.
            facOutEnc.fileWriteBd(bd, 0, 0);

            crypt.setFirstChunk(false);
        }

        // Make sure both FirstChunk and LastChunk are restored to true after
        // encrypting or decrypting in chunks.  Otherwise subsequent encryptions/decryptions
        // will produce unexpected results.
        crypt.setFirstChunk(true);
        crypt.setLastChunk(true);

        facIn.fileClose();
        facOutEnc.fileClose();

        // Decrypt the encrypted output file in a single call using CBC mode:
        String decryptedFile = "qa_output/hamlet_dec.xml";
        crypt.ckDecryptFile(outputEncryptedFile, decryptedFile);
        // Assume success for the example..

        // Compare the contents of the decrypted file with the original file:
        boolean bSame = facIn.fileContentsEqual(fileToEncrypt, decryptedFile);
        System.out.println("bSame = " + bSame);
    }
}