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Refactored bundle encryption code.

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This commit is contained in:
akwizgran
2013-02-19 00:41:50 +00:00
parent f33348ff98
commit 9215537d80
3 changed files with 75 additions and 45 deletions
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52
briar-android/src/net/sf/briar/android/BundleEncrypterImpl.java
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@@ -1,41 +1,27 @@
package net.sf.briar.android;
import static java.util.logging.Level.INFO;
import static javax.crypto.Cipher.DECRYPT_MODE;
import static javax.crypto.Cipher.ENCRYPT_MODE;
import java.security.GeneralSecurityException;
import java.security.SecureRandom;
import java.util.logging.Logger;
import net.sf.briar.api.android.BundleEncrypter;
import net.sf.briar.api.crypto.AuthenticatedCipher;
import net.sf.briar.api.crypto.CryptoComponent;
import net.sf.briar.api.crypto.ErasableKey;
import net.sf.briar.util.ByteUtils;
import android.os.Bundle;
import android.os.Parcel;
import com.google.inject.Inject;
// This class is not thread-safe
class BundleEncrypterImpl implements BundleEncrypter {
private static final Logger LOG =
Logger.getLogger(BundleEncrypterImpl.class.getName());
private final AuthenticatedCipher cipher;
private final SecureRandom random;
private final ErasableKey key;
private final int blockSize, macLength;
private final CryptoComponent crypto;
@Inject
BundleEncrypterImpl(CryptoComponent crypto) {
cipher = crypto.getBundleCipher();
random = crypto.getSecureRandom();
key = crypto.generateSecretKey();
blockSize = cipher.getBlockSize();
macLength = cipher.getMacLength();
this.crypto = crypto;
}
@Override
@@ -49,41 +35,23 @@ class BundleEncrypterImpl implements BundleEncrypter {
LOG.info("Marshalled " + b.size() + " mappings, "
+ plaintext.length + " plaintext bytes");
}
// Encrypt the byte array using a random IV
byte[] iv = new byte[blockSize];
random.nextBytes(iv);
byte[] ciphertext = new byte[plaintext.length + macLength];
try {
cipher.init(ENCRYPT_MODE, key, iv, null);
cipher.doFinal(plaintext, 0, plaintext.length, ciphertext, 0);
} catch(GeneralSecurityException e) {
throw new RuntimeException(e);
}
// Encrypt the plaintext
byte[] ciphertext = crypto.encryptTemporaryStorage(plaintext);
ByteUtils.erase(plaintext);
// Replace the plaintext contents with the IV and the ciphertext
// Replace the plaintext contents with the ciphertext
b.clear();
b.putByteArray("net.sf.briar.IV", iv);
b.putByteArray("net.sf.briar.CIPHERTEXT", ciphertext);
}
@Override
public boolean decrypt(Bundle b) {
// Retrieve the IV and the ciphertext
byte[] iv = b.getByteArray("net.sf.briar.IV");
if(iv == null) throw new IllegalArgumentException();
if(iv.length != blockSize) throw new IllegalArgumentException();
// Retrieve the ciphertext
byte[] ciphertext = b.getByteArray("net.sf.briar.CIPHERTEXT");
if(ciphertext == null) throw new IllegalArgumentException();
if(ciphertext.length < macLength) throw new IllegalArgumentException();
// Decrypt the ciphertext using the IV
byte[] plaintext = new byte[ciphertext.length - macLength];
try {
cipher.init(DECRYPT_MODE, key, iv, null);
cipher.doFinal(ciphertext, 0, ciphertext.length, plaintext, 0);
} catch(GeneralSecurityException e) {
return false; // Invalid ciphertext
}
// Unmarshall the byte array
// Decrypt the ciphertext
byte[] plaintext = crypto.decryptTemporaryStorage(ciphertext);
if(plaintext == null) return false;
// Unmarshall the plaintext
Parcel p = Parcel.obtain();
p.unmarshall(plaintext, 0, plaintext.length);
ByteUtils.erase(plaintext);