106 lines
2.8 KiB
Java
106 lines
2.8 KiB
Java
package org.whispersystems.textsecure.api.crypto;
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import org.whispersystems.textsecure.util.Util;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.security.InvalidKeyException;
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import java.security.NoSuchAlgorithmException;
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import javax.crypto.BadPaddingException;
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import javax.crypto.Cipher;
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import javax.crypto.IllegalBlockSizeException;
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import javax.crypto.Mac;
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import javax.crypto.NoSuchPaddingException;
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import javax.crypto.spec.SecretKeySpec;
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public class AttachmentCipherOutputStream extends OutputStream {
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private final Cipher cipher;
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private final Mac mac;
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private final OutputStream outputStream;
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private long ciphertextLength = 0;
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public AttachmentCipherOutputStream(byte[] combinedKeyMaterial,
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OutputStream outputStream)
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throws IOException
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{
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try {
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this.outputStream = outputStream;
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this.cipher = initializeCipher();
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this.mac = initializeMac();
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byte[][] keyParts = Util.split(combinedKeyMaterial, 32, 32);
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this.cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(keyParts[0], "AES"));
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this.mac.init(new SecretKeySpec(keyParts[1], "HmacSHA256"));
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mac.update(cipher.getIV());
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outputStream.write(cipher.getIV());
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ciphertextLength += cipher.getIV().length;
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} catch (InvalidKeyException e) {
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throw new AssertionError(e);
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}
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}
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@Override
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public void write(byte[] buffer) throws IOException {
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write(buffer, 0, buffer.length);
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}
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@Override
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public void write(byte[] buffer, int offset, int length) throws IOException {
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byte[] ciphertext = cipher.update(buffer, offset, length);
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if (ciphertext != null) {
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mac.update(ciphertext);
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outputStream.write(ciphertext);
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ciphertextLength += ciphertext.length;
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}
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}
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@Override
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public void write(int b) {
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throw new AssertionError("NYI");
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}
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@Override
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public void flush() throws IOException {
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try {
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byte[] ciphertext = cipher.doFinal();
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byte[] auth = mac.doFinal(ciphertext);
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outputStream.write(ciphertext);
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outputStream.write(auth);
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ciphertextLength += ciphertext.length;
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ciphertextLength += auth.length;
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outputStream.flush();
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} catch (IllegalBlockSizeException | BadPaddingException e) {
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throw new AssertionError(e);
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}
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}
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public static long getCiphertextLength(long plaintextLength) {
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return 16 + (((plaintextLength / 16) +1) * 16) + 32;
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}
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private Mac initializeMac() {
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try {
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return Mac.getInstance("HmacSHA256");
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} catch (NoSuchAlgorithmException e) {
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throw new AssertionError(e);
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}
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}
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private Cipher initializeCipher() {
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try {
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return Cipher.getInstance("AES/CBC/PKCS5Padding");
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} catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
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throw new AssertionError(e);
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}
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}
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}
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