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Code Issues Releases Wiki Activity

Upgrade settings file encryption

This commit is contained in:
M66B 2022-10-19 22:07:06 +02:00
parent 7bb187fbd4
commit 518afffea1
3 changed files with 44 additions and 17 deletions
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11
FAQ.md
View File

@ -1847,8 +1847,15 @@ Short version: AES 256 bit
Long version:
* The 256 bit key is generated with *PBKDF2WithHmacSHA1* using a 128 bit secure random salt and 65536 iterations
* The cipher is *AES/CBC/PKCS5Padding*
*Before version 1.1987*
* A 256 bit key is derived with *PBKDF2WithHmacSHA1* using a 128 bit secure random salt and 65536 iterations
* The used cipher is *AES/CBC/PKCS5Padding*
*Since version 1.1987*
* A 256 bit key is derived with *PBKDF2WithHmacSHA512* using a 128 bit secure random salt and 120000 iterations
* The used cipher is *AES/GCM/NoPadding*
<br />

48
app/src/main/java/eu/faircode/email/ActivitySetup.java
View File

@ -96,6 +96,7 @@ import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
@ -137,9 +138,6 @@ public class ActivitySetup extends ActivityBase implements FragmentManager.OnBac
private boolean import_answers;
private boolean import_settings;
private static final int KEY_ITERATIONS = 65536;
private static final int KEY_LENGTH = 256;
static final int REQUEST_SOUND_INBOUND = 1;
static final int REQUEST_SOUND_OUTBOUND = 2;
static final int REQUEST_EXPORT = 3;
@ -846,12 +844,14 @@ public class ActivitySetup extends ActivityBase implements FragmentManager.OnBac
random.nextBytes(salt);
// https://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, KEY_ITERATIONS, KEY_LENGTH);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA512");
KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, 120000, 256);
SecretKey secret = keyFactory.generateSecret(keySpec);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, secret);
raw.write("___FairEmail___".getBytes(StandardCharsets.US_ASCII));
raw.write(1); // version
raw.write(salt);
raw.write(cipher.getIV());
@ -998,16 +998,36 @@ public class ActivitySetup extends ActivityBase implements FragmentManager.OnBac
in = raw;
else {
byte[] salt = new byte[16];
byte[] prefix = new byte[16];
Helper.readBuffer(raw, salt);
Helper.readBuffer(raw, prefix);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, KEY_ITERATIONS, KEY_LENGTH);
int version = 0;
String magic = new String(salt, 0, 15, StandardCharsets.US_ASCII);
if ("___FairEmail___".equals(magic)) {
version = salt[15];
Helper.readBuffer(raw, salt);
}
int ivLen = (version == 0 ? 16 : 12);
String derivation = (version == 0 ? "PBKDF2WithHmacSHA1" : "PBKDF2WithHmacSHA512");
int iterations = (version == 0 ? 65536 : 120000);
int keyLen = 256;
String transformation = (version == 0 ? "AES/CBC/PKCS5Padding" : "AES/GCM/NoPadding");
Log.i("Import version=" + version +
" ivLen=" + ivLen +
" derivation=" + derivation +
" iterations=" + iterations +
" keyLen=" + keyLen +
" transformation=" + transformation);
byte[] iv = new byte[ivLen];
Helper.readBuffer(raw, iv);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(derivation);
KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, iterations, 256);
SecretKey secret = keyFactory.generateSecret(keySpec);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec iv = new IvParameterSpec(prefix);
cipher.init(Cipher.DECRYPT_MODE, secret, iv);
Cipher cipher = Cipher.getInstance(transformation);
IvParameterSpec ivSpec = new IvParameterSpec(iv);
cipher.init(Cipher.DECRYPT_MODE, secret, ivSpec);
in = new CipherInputStream(raw, cipher);
}
@ -1447,7 +1467,7 @@ public class ActivitySetup extends ActivityBase implements FragmentManager.OnBac
((NoStreamException) ex).report(ActivitySetup.this);
else {
SpannableStringBuilder ssb = new SpannableStringBuilder();
if (ex.getCause() instanceof BadPaddingException)
if (ex.getCause() instanceof BadPaddingException /* GCM: AEADBadTagException */)
ssb.append(getString(R.string.title_setup_password_invalid));
else if (ex instanceof IOException && ex.getCause() instanceof IllegalBlockSizeException)
ssb.append(getString(R.string.title_setup_import_invalid));

2
app/src/main/res/values/strings.xml
View File

@ -297,7 +297,7 @@
<string name="title_setup_password_repeat">Repeat password</string>
<string name="title_setup_password_missing">Password missing</string>
<string name="title_setup_password_different">Passwords don\'t match</string>
<string name="title_setup_password_invalid">Password invalid</string>
<string name="title_setup_password_invalid">Incorrect password, or damaged settings file</string>
<string name="title_setup_import_accounts">Import accounts and identities</string>
<string name="title_setup_import_delete">Delete existing accounts first</string>
<string name="title_setup_import_rules">Import filter rules</string>