+ private static final int BATCH_SIZE = 100;
+
+ private List<PreKeyRecord> generatePreKeys() {
+ List<PreKeyRecord> records = new LinkedList<>();
+
+ for (int i = 0; i < BATCH_SIZE; i++) {
+ int preKeyId = (preKeyIdOffset + i) % Medium.MAX_VALUE;
+ ECKeyPair keyPair = Curve.generateKeyPair();
+ PreKeyRecord record = new PreKeyRecord(preKeyId, keyPair);
+
+ axolotlStore.storePreKey(preKeyId, record);
+ records.add(record);
+ }
+
+ preKeyIdOffset = (preKeyIdOffset + BATCH_SIZE + 1) % Medium.MAX_VALUE;
+ return records;
+ }
+
+ private PreKeyRecord generateLastResortPreKey() {
+ if (axolotlStore.containsPreKey(Medium.MAX_VALUE)) {
+ try {
+ return axolotlStore.loadPreKey(Medium.MAX_VALUE);
+ } catch (InvalidKeyIdException e) {
+ axolotlStore.removePreKey(Medium.MAX_VALUE);
+ }
+ }
+
+ ECKeyPair keyPair = Curve.generateKeyPair();
+ PreKeyRecord record = new PreKeyRecord(Medium.MAX_VALUE, keyPair);
+
+ axolotlStore.storePreKey(Medium.MAX_VALUE, record);
+
+ return record;
+ }
+
+ private SignedPreKeyRecord generateSignedPreKey(IdentityKeyPair identityKeyPair) {
+ try {
+ ECKeyPair keyPair = Curve.generateKeyPair();
+ byte[] signature = Curve.calculateSignature(identityKeyPair.getPrivateKey(), keyPair.getPublicKey().serialize());
+ SignedPreKeyRecord record = new SignedPreKeyRecord(nextSignedPreKeyId, System.currentTimeMillis(), keyPair, signature);
+
+ axolotlStore.storeSignedPreKey(nextSignedPreKeyId, record);
+ nextSignedPreKeyId = (nextSignedPreKeyId + 1) % Medium.MAX_VALUE;
+
+ return record;
+ } catch (InvalidKeyException e) {
+ throw new AssertionError(e);
+ }
+ }
+