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Code Issues Releases Wiki Activity

Add hash of data key to AD

This commit is contained in:
M66B 2023-01-15 16:12:25 +01:00
parent c223f8ef1e
commit 7f022c31a0
1 changed files with 14 additions and 5 deletions
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19
app/src/main/java/eu/faircode/email/CloudSync.java
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@ -121,7 +121,7 @@ public class CloudSync {
String v = null;
if (jitem.has("val") && !jitem.isNull("val")) {
v = jitem.getString("val");
jitem.put("val", transform(v, key.second, revision, true));
jitem.put("val", transform(v, key.second, getAd(k, revision), true));
}
v = (v == null ? null : "#" + v.length());
@ -189,7 +189,7 @@ public class CloudSync {
String v = null;
if (jitem.has("val") && !jitem.isNull("val")) {
String evalue = jitem.getString("val");
v = transform(evalue, key.second, revision, false);
v = transform(evalue, key.second, getAd(k, revision), false);
jitem.put("val", v);
}
v = (v == null ? null : "#" + v.length());
@ -218,13 +218,22 @@ public class CloudSync {
Arrays.copyOfRange(encoded, half, half + half));
}
private static String transform(String value, byte[] key, Integer revision, boolean encrypt) throws GeneralSecurityException {
private static byte[] getAd(String key, int revision) throws NoSuchAlgorithmException {
byte[] k = MessageDigest.getInstance("SHA256").digest(key.getBytes());
byte[] ad = ByteBuffer.allocate(4 + 8)
.putInt(revision)
.put(Arrays.copyOfRange(k, 0, 8))
.array();
return ad;
}
private static String transform(String value, byte[] key, byte[] ad, boolean encrypt) throws GeneralSecurityException {
SecretKeySpec secret = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/GCM-SIV/NoPadding");
IvParameterSpec ivSpec = new IvParameterSpec(new byte[12]);
cipher.init(encrypt ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE, secret, ivSpec);
if (revision != null)
cipher.updateAAD(ByteBuffer.allocate(4).putInt(revision).array());
if (ad != null)
cipher.updateAAD(ad);
if (encrypt) {
byte[] encrypted = cipher.doFinal(value.getBytes());
return Base64.encodeToString(encrypted, Base64.NO_PADDING | Base64.NO_WRAP);