diff options
Diffstat (limited to 'mobile/android/services/src/main/java/org/mozilla/gecko/sync/crypto/KeyBundle.java')
-rw-r--r-- | mobile/android/services/src/main/java/org/mozilla/gecko/sync/crypto/KeyBundle.java | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/mobile/android/services/src/main/java/org/mozilla/gecko/sync/crypto/KeyBundle.java b/mobile/android/services/src/main/java/org/mozilla/gecko/sync/crypto/KeyBundle.java new file mode 100644 index 000000000..2063b1e32 --- /dev/null +++ b/mobile/android/services/src/main/java/org/mozilla/gecko/sync/crypto/KeyBundle.java @@ -0,0 +1,135 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +package org.mozilla.gecko.sync.crypto; + +import java.io.UnsupportedEncodingException; +import java.security.InvalidKeyException; +import java.security.NoSuchAlgorithmException; +import java.util.Arrays; + +import javax.crypto.KeyGenerator; +import javax.crypto.Mac; + +import org.mozilla.apache.commons.codec.binary.Base64; +import org.mozilla.gecko.sync.Utils; + +public class KeyBundle { + private static final String KEY_ALGORITHM_SPEC = "AES"; + private static final int KEY_SIZE = 256; + + private byte[] encryptionKey; + private byte[] hmacKey; + + // These are the same for every sync key bundle. + private static final byte[] EMPTY_BYTES = {}; + private static final byte[] ENCR_INPUT_BYTES = {1}; + private static final byte[] HMAC_INPUT_BYTES = {2}; + + /* + * Mozilla's use of HKDF for getting keys from the Sync Key string. + * + * We do exactly 2 HKDF iterations and make the first iteration the + * encryption key and the second iteration the HMAC key. + * + */ + public KeyBundle(String username, String base32SyncKey) throws CryptoException { + if (base32SyncKey == null) { + throw new IllegalArgumentException("No sync key provided."); + } + if (username == null || username.equals("")) { + throw new IllegalArgumentException("No username provided."); + } + // Hash appropriately. + try { + username = Utils.usernameFromAccount(username); + } catch (NoSuchAlgorithmException | UnsupportedEncodingException e) { + throw new IllegalArgumentException("Invalid username."); + } + + byte[] syncKey = Utils.decodeFriendlyBase32(base32SyncKey); + byte[] user = username.getBytes(); + + Mac hmacHasher; + try { + hmacHasher = HKDF.makeHMACHasher(syncKey); + } catch (NoSuchAlgorithmException | InvalidKeyException e) { + throw new CryptoException(e); + } + assert(hmacHasher != null); // If makeHMACHasher doesn't throw, then hmacHasher is non-null. + + byte[] encrBytes = Utils.concatAll(EMPTY_BYTES, HKDF.HMAC_INPUT, user, ENCR_INPUT_BYTES); + byte[] encrKey = HKDF.digestBytes(encrBytes, hmacHasher); + byte[] hmacBytes = Utils.concatAll(encrKey, HKDF.HMAC_INPUT, user, HMAC_INPUT_BYTES); + + this.hmacKey = HKDF.digestBytes(hmacBytes, hmacHasher); + this.encryptionKey = encrKey; + } + + public KeyBundle(byte[] encryptionKey, byte[] hmacKey) { + this.setEncryptionKey(encryptionKey); + this.setHMACKey(hmacKey); + } + + /** + * Make a KeyBundle with the specified base64-encoded keys. + * + * @return A KeyBundle with the specified keys. + */ + public static KeyBundle fromBase64EncodedKeys(String base64EncryptionKey, String base64HmacKey) throws UnsupportedEncodingException { + return new KeyBundle(Base64.decodeBase64(base64EncryptionKey.getBytes("UTF-8")), + Base64.decodeBase64(base64HmacKey.getBytes("UTF-8"))); + } + + /** + * Make a KeyBundle with two random 256 bit keys (encryption and HMAC). + * + * @return A KeyBundle with random keys. + */ + public static KeyBundle withRandomKeys() throws CryptoException { + KeyGenerator keygen; + try { + keygen = KeyGenerator.getInstance(KEY_ALGORITHM_SPEC); + } catch (NoSuchAlgorithmException e) { + throw new CryptoException(e); + } + + keygen.init(KEY_SIZE); + byte[] encryptionKey = keygen.generateKey().getEncoded(); + byte[] hmacKey = keygen.generateKey().getEncoded(); + + return new KeyBundle(encryptionKey, hmacKey); + } + + public byte[] getEncryptionKey() { + return encryptionKey; + } + + public void setEncryptionKey(byte[] encryptionKey) { + this.encryptionKey = encryptionKey; + } + + public byte[] getHMACKey() { + return hmacKey; + } + + public void setHMACKey(byte[] hmacKey) { + this.hmacKey = hmacKey; + } + + @Override + public boolean equals(Object o) { + if (!(o instanceof KeyBundle)) { + return false; + } + KeyBundle other = (KeyBundle) o; + return Arrays.equals(other.encryptionKey, this.encryptionKey) && + Arrays.equals(other.hmacKey, this.hmacKey); + } + + @Override + public int hashCode() { + throw new UnsupportedOperationException("No hashCode for KeyBundle."); + } +} |