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Unverified Commit 9c8125d7 authored by akwizgran's avatar akwizgran
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Rename 'alice' flags to clarify usage, add comments.

parent 1a1a010e
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    bramble-core/src/main/java/org/briarproject/bramble/crypto/TransportCryptoImpl.java
    View file @ 9c8125d7
    ......@@ -43,12 +43,13 @@ class TransportCryptoImpl implements TransportCrypto {
    @Override
    public TransportKeys deriveTransportKeys(TransportId t,
    SecretKey rootKey, long timePeriod, boolean alice, boolean active) {
    SecretKey rootKey, long timePeriod, boolean weAreAlice,
    boolean active) {
    // Keys for the previous period are derived from the root key
    SecretKey inTagPrev = deriveTagKey(rootKey, t, !alice);
    SecretKey inHeaderPrev = deriveHeaderKey(rootKey, t, !alice);
    SecretKey outTagPrev = deriveTagKey(rootKey, t, alice);
    SecretKey outHeaderPrev = deriveHeaderKey(rootKey, t, alice);
    SecretKey inTagPrev = deriveTagKey(rootKey, t, !weAreAlice);
    SecretKey inHeaderPrev = deriveHeaderKey(rootKey, t, !weAreAlice);
    SecretKey outTagPrev = deriveTagKey(rootKey, t, weAreAlice);
    SecretKey outHeaderPrev = deriveHeaderKey(rootKey, t, weAreAlice);
    // Derive the keys for the current and next periods
    SecretKey inTagCurr = rotateKey(inTagPrev, timePeriod);
    SecretKey inHeaderCurr = rotateKey(inHeaderPrev, timePeriod);
    ......@@ -101,54 +102,57 @@ class TransportCryptoImpl implements TransportCrypto {
    }
    private SecretKey deriveTagKey(SecretKey rootKey, TransportId t,
    boolean alice) {
    String label = alice ? ALICE_TAG_LABEL : BOB_TAG_LABEL;
    boolean keyBelongsToAlice) {
    String label = keyBelongsToAlice ? ALICE_TAG_LABEL : BOB_TAG_LABEL;
    byte[] id = toUtf8(t.getString());
    return crypto.deriveKey(label, rootKey, id);
    }
    private SecretKey deriveHeaderKey(SecretKey rootKey, TransportId t,
    boolean alice) {
    String label = alice ? ALICE_HEADER_LABEL : BOB_HEADER_LABEL;
    boolean keyBelongsToAlice) {
    String label = keyBelongsToAlice ? ALICE_HEADER_LABEL :
    BOB_HEADER_LABEL;
    byte[] id = toUtf8(t.getString());
    return crypto.deriveKey(label, rootKey, id);
    }
    @Override
    public HandshakeKeys deriveHandshakeKeys(TransportId t, SecretKey rootKey,
    long timePeriod, boolean alice) {
    long timePeriod, boolean weAreAlice) {
    if (timePeriod < 1) throw new IllegalArgumentException();
    IncomingKeys inPrev = deriveIncomingHandshakeKeys(t, rootKey, alice,
    timePeriod - 1);
    IncomingKeys inCurr = deriveIncomingHandshakeKeys(t, rootKey, alice,
    timePeriod);
    IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey, alice,
    timePeriod + 1);
    OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey, alice,
    timePeriod);
    IncomingKeys inPrev = deriveIncomingHandshakeKeys(t, rootKey,
    weAreAlice, timePeriod - 1);
    IncomingKeys inCurr = deriveIncomingHandshakeKeys(t, rootKey,
    weAreAlice, timePeriod);
    IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey,
    weAreAlice, timePeriod + 1);
    OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey,
    weAreAlice, timePeriod);
    return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr, rootKey,
    alice);
    weAreAlice);
    }
    private IncomingKeys deriveIncomingHandshakeKeys(TransportId t,
    SecretKey rootKey, boolean alice, long timePeriod) {
    SecretKey tag = deriveHandshakeTagKey(t, rootKey, !alice, timePeriod);
    SecretKey header = deriveHandshakeHeaderKey(t, rootKey, !alice,
    SecretKey rootKey, boolean weAreAlice, long timePeriod) {
    SecretKey tag = deriveHandshakeTagKey(t, rootKey, !weAreAlice,
    timePeriod);
    SecretKey header = deriveHandshakeHeaderKey(t, rootKey, !weAreAlice,
    timePeriod);
    return new IncomingKeys(tag, header, timePeriod);
    }
    private OutgoingKeys deriveOutgoingHandshakeKeys(TransportId t,
    SecretKey rootKey, boolean alice, long timePeriod) {
    SecretKey tag = deriveHandshakeTagKey(t, rootKey, alice, timePeriod);
    SecretKey header = deriveHandshakeHeaderKey(t, rootKey, alice,
    SecretKey rootKey, boolean weAreAlice, long timePeriod) {
    SecretKey tag = deriveHandshakeTagKey(t, rootKey, weAreAlice,
    timePeriod);
    SecretKey header = deriveHandshakeHeaderKey(t, rootKey, weAreAlice,
    timePeriod);
    return new OutgoingKeys(tag, header, timePeriod, true);
    }
    private SecretKey deriveHandshakeTagKey(TransportId t, SecretKey rootKey,
    boolean alice, long timePeriod) {
    String label = alice ? ALICE_HANDSHAKE_TAG_LABEL :
    boolean keyBelongsToAlice, long timePeriod) {
    String label = keyBelongsToAlice ? ALICE_HANDSHAKE_TAG_LABEL :
    BOB_HANDSHAKE_TAG_LABEL;
    byte[] id = toUtf8(t.getString());
    byte[] period = new byte[INT_64_BYTES];
    ......@@ -157,8 +161,8 @@ class TransportCryptoImpl implements TransportCrypto {
    }
    private SecretKey deriveHandshakeHeaderKey(TransportId t, SecretKey rootKey,
    boolean alice, long timePeriod) {
    String label = alice ? ALICE_HANDSHAKE_HEADER_LABEL :
    boolean keyBelongsToAlice, long timePeriod) {
    String label = keyBelongsToAlice ? ALICE_HANDSHAKE_HEADER_LABEL :
    BOB_HANDSHAKE_HEADER_LABEL;
    byte[] id = toUtf8(t.getString());
    byte[] period = new byte[INT_64_BYTES];
    ......@@ -171,34 +175,36 @@ class TransportCryptoImpl implements TransportCrypto {
    long elapsed = timePeriod - k.getTimePeriod();
    TransportId t = k.getTransportId();
    SecretKey rootKey = k.getRootKey();
    boolean alice = k.isAlice();
    boolean weAreAlice = k.isAlice();
    if (elapsed <= 0) {
    // The keys are for the given period or later - don't update them
    return k;
    } else if (elapsed == 1) {
    // The keys are one period old - shift by one period
    // The keys are one period old - shift by one period, keeping the
    // reordering windows for keys we retain
    IncomingKeys inPrev = k.getCurrentIncomingKeys();
    IncomingKeys inCurr = k.getNextIncomingKeys();
    IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey,
    alice, timePeriod + 1);
    weAreAlice, timePeriod + 1);
    OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey,
    alice, timePeriod);
    weAreAlice, timePeriod);
    return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr,
    rootKey, alice);
    rootKey, weAreAlice);
    } else if (elapsed == 2) {
    // The keys are two periods old - shift by two periods
    // The keys are two periods old - shift by two periods, keeping
    // the reordering windows for keys we retain
    IncomingKeys inPrev = k.getNextIncomingKeys();
    IncomingKeys inCurr = deriveIncomingHandshakeKeys(t, rootKey,
    alice, timePeriod);
    weAreAlice, timePeriod);
    IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey,
    alice, timePeriod + 1);
    weAreAlice, timePeriod + 1);
    OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey,
    alice, timePeriod);
    weAreAlice, timePeriod);
    return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr,
    rootKey, alice);
    rootKey, weAreAlice);
    } else {
    // The keys are more than two periods old - derive fresh keys
    return deriveHandshakeKeys(t, rootKey, timePeriod, alice);
    return deriveHandshakeKeys(t, rootKey, timePeriod, weAreAlice);
    }
    }
    ......
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