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Diffstat (limited to 'src/main/java/org/whispersystems/libaxolotl/ratchet/RootKey.java')
-rw-r--r-- | src/main/java/org/whispersystems/libaxolotl/ratchet/RootKey.java | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/src/main/java/org/whispersystems/libaxolotl/ratchet/RootKey.java b/src/main/java/org/whispersystems/libaxolotl/ratchet/RootKey.java new file mode 100644 index 00000000..39f3a831 --- /dev/null +++ b/src/main/java/org/whispersystems/libaxolotl/ratchet/RootKey.java @@ -0,0 +1,54 @@ +/** + * Copyright (C) 2014 Open Whisper Systems + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +package org.whispersystems.libaxolotl.ratchet; + +import org.whispersystems.libaxolotl.InvalidKeyException; +import org.whispersystems.libaxolotl.ecc.Curve; +import org.whispersystems.libaxolotl.ecc.ECKeyPair; +import org.whispersystems.libaxolotl.ecc.ECPublicKey; +import org.whispersystems.libaxolotl.kdf.DerivedRootSecrets; +import org.whispersystems.libaxolotl.kdf.HKDF; +import org.whispersystems.libaxolotl.util.ByteUtil; +import org.whispersystems.libaxolotl.util.Pair; + +public class RootKey { + + private final HKDF kdf; + private final byte[] key; + + public RootKey(HKDF kdf, byte[] key) { + this.kdf = kdf; + this.key = key; + } + + public byte[] getKeyBytes() { + return key; + } + + public Pair<RootKey, ChainKey> createChain(ECPublicKey theirRatchetKey, ECKeyPair ourRatchetKey) + throws InvalidKeyException + { + byte[] sharedSecret = Curve.calculateAgreement(theirRatchetKey, ourRatchetKey.getPrivateKey()); + byte[] derivedSecretBytes = kdf.deriveSecrets(sharedSecret, key, "WhisperRatchet".getBytes(), DerivedRootSecrets.SIZE); + DerivedRootSecrets derivedSecrets = new DerivedRootSecrets(derivedSecretBytes); + + RootKey newRootKey = new RootKey(kdf, derivedSecrets.getRootKey()); + ChainKey newChainKey = new ChainKey(kdf, derivedSecrets.getChainKey(), 0); + + return new Pair<>(newRootKey, newChainKey); + } +} |