OpenSSLPBEOutputStream.java

package info.guardianproject.otr;

import java.io.IOException;
import java.io.OutputStream;
import java.security.SecureRandom;

import javax.crypto.Cipher;

public class OpenSSLPBEOutputStream extends OutputStream {

private static final int BUFFER_SIZE = 5 * 1024 * 1024;

private final Cipher cipher;
private final OutputStream outStream;
private final byte[] buffer = new byte[BUFFER_SIZE];
private int bufferIndex = 0;

public OpenSSLPBEOutputStream(final OutputStream outputStream, String algIn, int iterationCount,
                              char[] password) throws IOException {
    outStream = outputStream;
    try {
        /* Create and use a random SALT for each instance of this output stream. */
        byte[] salt = new byte[OpenSSLPBECommon.SALT_SIZE_BYTES];
        new SecureRandom().nextBytes(salt);
        cipher = OpenSSLPBECommon.initializeCipher(password, salt, Cipher.ENCRYPT_MODE, algIn, iterationCount);
        /* Write header */
        writeHeader(salt);
    } catch (Exception e) {
        throw new IOException(e);
    }
}

@Override
public void write(int b) throws IOException {
    buffer[bufferIndex] = (byte) b;
    bufferIndex++;
    if (bufferIndex == BUFFER_SIZE) {
        byte[] result = cipher.update(buffer, 0, bufferIndex);
        outStream.write(result);
        bufferIndex = 0;
    }
}

@Override
public void flush() throws IOException {
    if (bufferIndex > 0) {
        byte[] result;
        try {
            result = cipher.doFinal(buffer, 0, bufferIndex);
            outStream.write(result);
        } catch (Exception e) {
            throw new IOException(e);
        }
        bufferIndex = 0;
    }
}

@Override
public void close() throws IOException {
    flush();
    outStream.close();
}

private void writeHeader(byte[] salt) throws IOException {
    outStream.write(OpenSSLPBECommon.OPENSSL_HEADER_STRING.getBytes(OpenSSLPBECommon.OPENSSL_HEADER_ENCODE));
    outStream.write(salt);
}

}