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Crypto: refactor the Cipher class.

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Include the hmac in the cipher class.
Derive keys on class creation instead of on encrypt/decrypt.
This commit is contained in:
Tom Hacohen 2017-03-29 12:27:22 +01:00
parent 0fbee1ea02
commit abd13d4d3d
2 changed files with 37 additions and 31 deletions
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18
app/src/main/java/com/etesync/syncadapter/journalmanager/BaseManager.java
View File

@ -1,5 +1,8 @@
package com.etesync.syncadapter.journalmanager;
import com.etesync.syncadapter.App;
import com.etesync.syncadapter.GsonHelper;
import org.apache.commons.codec.Charsets;
import java.io.ByteArrayOutputStream;
@ -7,9 +10,6 @@ import java.io.IOException;
import java.net.HttpURLConnection;
import java.util.logging.Level;
import com.etesync.syncadapter.App;
import com.etesync.syncadapter.GsonHelper;
import lombok.AccessLevel;
import lombok.Getter;
import lombok.Setter;
@ -19,8 +19,6 @@ import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import static com.etesync.syncadapter.journalmanager.Crypto.hmac;
abstract class BaseManager {
final static protected MediaType JSON = MediaType.parse("application/json; charset=utf-8");
@ -77,12 +75,14 @@ abstract class BaseManager {
public String getContent(String keyBase64) {
// FIXME: probably cache encryption object
return new String(new Crypto.Cipher().decrypt(keyBase64, content), Charsets.UTF_8);
Crypto.Cipher cipher = new Crypto.Cipher(keyBase64, null);
return new String(cipher.decrypt(content), Charsets.UTF_8);
}
void setContent(String keyBase64, String content) {
// FIXME: probably cache encryption object
this.content = new Crypto.Cipher().encrypt(keyBase64, content.getBytes(Charsets.UTF_8));
Crypto.Cipher cipher = new Crypto.Cipher(keyBase64, null);
this.content = cipher.encrypt(content.getBytes(Charsets.UTF_8));
}
byte[] calculateHmac(String keyBase64, String uuid) {
@ -99,7 +99,9 @@ abstract class BaseManager {
return "DEADBEEFDEADBEEFDEADBEEFDEADBEEF".getBytes();
}
return hmac(keyBase64, hashContent.toByteArray());
// FIXME: probably cache encryption object
Crypto.Cipher cipher = new Crypto.Cipher(keyBase64, null);
return cipher.hmac(hashContent.toByteArray());
}
protected Base() {

50
app/src/main/java/com/etesync/syncadapter/journalmanager/Crypto.java
View File

@ -31,32 +31,22 @@ public class Crypto {
return Base64.encodeToString(SCrypt.generate(password.getBytes(Charsets.UTF_8), salt.getBytes(Charsets.UTF_8), 16384, 8, 1, keySize), Base64.NO_WRAP);
}
private static byte[] hmac256(byte[] keyByte, byte[] data) {
HMac hmac = new HMac(new SHA256Digest());
KeyParameter key = new KeyParameter(keyByte);
byte[] ret = new byte[hmac.getMacSize()];
hmac.init(key);
hmac.update(data, 0, data.length);
hmac.doFinal(ret, 0);
return ret;
}
static byte[] hmac(String keyBase64, byte[] data) {
byte[] derivedKey = hmac256("hmac".getBytes(Charsets.UTF_8), Base64.decode(keyBase64, Base64.NO_WRAP));
return hmac256(derivedKey, data);
}
static class Cipher {
private SecureRandom _random = null;
private final byte[] cipherKey;
private final byte[] hmacKey;
Cipher() {
Cipher(String keyBase64, String salt) {
byte[] derivedKey; // FIXME use salt = hmac256(salt.getBytes(Charsets.UTF_8), Base64.decode(keyBase64, Base64.NO_WRAP));
derivedKey = Base64.decode(keyBase64, Base64.NO_WRAP);
cipherKey = hmac256("aes".getBytes(Charsets.UTF_8), derivedKey);
hmacKey = hmac256("hmac".getBytes(Charsets.UTF_8), derivedKey);
}
private static final int blockSize = 16; // AES's block size in bytes
private BufferedBlockCipher getCipher(String keyBase64, byte[] iv, boolean encrypt) {
byte[] derivedKey = hmac256("aes".getBytes(Charsets.UTF_8), Base64.decode(keyBase64, Base64.NO_WRAP));
KeyParameter key = new KeyParameter(derivedKey);
private BufferedBlockCipher getCipher(byte[] iv, boolean encrypt) {
KeyParameter key = new KeyParameter(cipherKey);
CipherParameters params = new ParametersWithIV(key, iv);
BlockCipherPadding padding = new PKCS7Padding();
@ -68,11 +58,11 @@ public class Crypto {
return cipher;
}
byte[] decrypt(String keyBase64, byte[] _data) {
byte[] decrypt(byte[] _data) {
byte[] iv = Arrays.copyOfRange(_data, 0, blockSize);
byte[] data = Arrays.copyOfRange(_data, blockSize, _data.length);
BufferedBlockCipher cipher = getCipher(keyBase64, iv, false);
BufferedBlockCipher cipher = getCipher(iv, false);
byte[] buf = new byte[cipher.getOutputSize(data.length)];
int len = cipher.processBytes(data, 0, data.length, buf, 0);
@ -91,11 +81,11 @@ public class Crypto {
return out;
}
byte[] encrypt(String keyBase64, byte[] data) {
byte[] encrypt(byte[] data) {
byte[] iv = new byte[blockSize];
getRandom().nextBytes(iv);
BufferedBlockCipher cipher = getCipher(keyBase64, iv, true);
BufferedBlockCipher cipher = getCipher(iv, true);
byte[] buf = new byte[cipher.getOutputSize(data.length) + blockSize];
System.arraycopy(iv, 0, buf, 0, iv.length);
@ -111,12 +101,26 @@ public class Crypto {
return buf;
}
byte[] hmac(byte[] data) {
return hmac256(hmacKey, data);
}
private SecureRandom getRandom() {
if (_random == null) {
_random = new SecureRandom();
}
return _random;
}
private static byte[] hmac256(byte[] keyByte, byte[] data) {
HMac hmac = new HMac(new SHA256Digest());
KeyParameter key = new KeyParameter(keyByte);
byte[] ret = new byte[hmac.getMacSize()];
hmac.init(key);
hmac.update(data, 0, data.length);
hmac.doFinal(ret, 0);
return ret;
}
}
static String sha256(String base) {