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Rename 'alice' flags to clarify usage, add comments.

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This commit is contained in:
akwizgran
2019-04-19 11:57:55 +01:00
parent 1a1a010ee7
commit 9c8125d77a
1 changed files with 46 additions and 40 deletions
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86
bramble-core/src/main/java/org/briarproject/bramble/crypto/TransportCryptoImpl.java
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@@ -43,12 +43,13 @@ class TransportCryptoImpl implements TransportCrypto {
@Override @Override
public TransportKeys deriveTransportKeys(TransportId t, 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 // Keys for the previous period are derived from the root key
SecretKey inTagPrev = deriveTagKey(rootKey, t, !alice); SecretKey inTagPrev = deriveTagKey(rootKey, t, !weAreAlice);
SecretKey inHeaderPrev = deriveHeaderKey(rootKey, t, !alice); SecretKey inHeaderPrev = deriveHeaderKey(rootKey, t, !weAreAlice);
SecretKey outTagPrev = deriveTagKey(rootKey, t, alice); SecretKey outTagPrev = deriveTagKey(rootKey, t, weAreAlice);
SecretKey outHeaderPrev = deriveHeaderKey(rootKey, t, alice); SecretKey outHeaderPrev = deriveHeaderKey(rootKey, t, weAreAlice);
// Derive the keys for the current and next periods // Derive the keys for the current and next periods
SecretKey inTagCurr = rotateKey(inTagPrev, timePeriod); SecretKey inTagCurr = rotateKey(inTagPrev, timePeriod);
SecretKey inHeaderCurr = rotateKey(inHeaderPrev, timePeriod); SecretKey inHeaderCurr = rotateKey(inHeaderPrev, timePeriod);
@@ -101,54 +102,57 @@ class TransportCryptoImpl implements TransportCrypto {
} }
private SecretKey deriveTagKey(SecretKey rootKey, TransportId t, private SecretKey deriveTagKey(SecretKey rootKey, TransportId t,
boolean alice) { boolean keyBelongsToAlice) {
String label = alice ? ALICE_TAG_LABEL : BOB_TAG_LABEL; String label = keyBelongsToAlice ? ALICE_TAG_LABEL : BOB_TAG_LABEL;
byte[] id = toUtf8(t.getString()); byte[] id = toUtf8(t.getString());
return crypto.deriveKey(label, rootKey, id); return crypto.deriveKey(label, rootKey, id);
} }
private SecretKey deriveHeaderKey(SecretKey rootKey, TransportId t, private SecretKey deriveHeaderKey(SecretKey rootKey, TransportId t,
boolean alice) { boolean keyBelongsToAlice) {
String label = alice ? ALICE_HEADER_LABEL : BOB_HEADER_LABEL; String label = keyBelongsToAlice ? ALICE_HEADER_LABEL :
BOB_HEADER_LABEL;
byte[] id = toUtf8(t.getString()); byte[] id = toUtf8(t.getString());
return crypto.deriveKey(label, rootKey, id); return crypto.deriveKey(label, rootKey, id);
} }
@Override @Override
public HandshakeKeys deriveHandshakeKeys(TransportId t, SecretKey rootKey, public HandshakeKeys deriveHandshakeKeys(TransportId t, SecretKey rootKey,
long timePeriod, boolean alice) { long timePeriod, boolean weAreAlice) {
if (timePeriod < 1) throw new IllegalArgumentException(); if (timePeriod < 1) throw new IllegalArgumentException();
IncomingKeys inPrev = deriveIncomingHandshakeKeys(t, rootKey, alice, IncomingKeys inPrev = deriveIncomingHandshakeKeys(t, rootKey,
timePeriod - 1); weAreAlice, timePeriod - 1);
IncomingKeys inCurr = deriveIncomingHandshakeKeys(t, rootKey, alice, IncomingKeys inCurr = deriveIncomingHandshakeKeys(t, rootKey,
timePeriod); weAreAlice, timePeriod);
IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey, alice, IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey,
timePeriod + 1); weAreAlice, timePeriod + 1);
OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey, alice, OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey,
timePeriod); weAreAlice, timePeriod);
return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr, rootKey, return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr, rootKey,
alice); weAreAlice);
} }
private IncomingKeys deriveIncomingHandshakeKeys(TransportId t, private IncomingKeys deriveIncomingHandshakeKeys(TransportId t,
SecretKey rootKey, boolean alice, long timePeriod) { SecretKey rootKey, boolean weAreAlice, long timePeriod) {
SecretKey tag = deriveHandshakeTagKey(t, rootKey, !alice, timePeriod); SecretKey tag = deriveHandshakeTagKey(t, rootKey, !weAreAlice,
SecretKey header = deriveHandshakeHeaderKey(t, rootKey, !alice, timePeriod);
SecretKey header = deriveHandshakeHeaderKey(t, rootKey, !weAreAlice,
timePeriod); timePeriod);
return new IncomingKeys(tag, header, timePeriod); return new IncomingKeys(tag, header, timePeriod);
} }
private OutgoingKeys deriveOutgoingHandshakeKeys(TransportId t, private OutgoingKeys deriveOutgoingHandshakeKeys(TransportId t,
SecretKey rootKey, boolean alice, long timePeriod) { SecretKey rootKey, boolean weAreAlice, long timePeriod) {
SecretKey tag = deriveHandshakeTagKey(t, rootKey, alice, timePeriod); SecretKey tag = deriveHandshakeTagKey(t, rootKey, weAreAlice,
SecretKey header = deriveHandshakeHeaderKey(t, rootKey, alice, timePeriod);
SecretKey header = deriveHandshakeHeaderKey(t, rootKey, weAreAlice,
timePeriod); timePeriod);
return new OutgoingKeys(tag, header, timePeriod, true); return new OutgoingKeys(tag, header, timePeriod, true);
} }
private SecretKey deriveHandshakeTagKey(TransportId t, SecretKey rootKey, private SecretKey deriveHandshakeTagKey(TransportId t, SecretKey rootKey,
boolean alice, long timePeriod) { boolean keyBelongsToAlice, long timePeriod) {
String label = alice ? ALICE_HANDSHAKE_TAG_LABEL : String label = keyBelongsToAlice ? ALICE_HANDSHAKE_TAG_LABEL :
BOB_HANDSHAKE_TAG_LABEL; BOB_HANDSHAKE_TAG_LABEL;
byte[] id = toUtf8(t.getString()); byte[] id = toUtf8(t.getString());
byte[] period = new byte[INT_64_BYTES]; byte[] period = new byte[INT_64_BYTES];
@@ -157,8 +161,8 @@ class TransportCryptoImpl implements TransportCrypto {
} }
private SecretKey deriveHandshakeHeaderKey(TransportId t, SecretKey rootKey, private SecretKey deriveHandshakeHeaderKey(TransportId t, SecretKey rootKey,
boolean alice, long timePeriod) { boolean keyBelongsToAlice, long timePeriod) {
String label = alice ? ALICE_HANDSHAKE_HEADER_LABEL : String label = keyBelongsToAlice ? ALICE_HANDSHAKE_HEADER_LABEL :
BOB_HANDSHAKE_HEADER_LABEL; BOB_HANDSHAKE_HEADER_LABEL;
byte[] id = toUtf8(t.getString()); byte[] id = toUtf8(t.getString());
byte[] period = new byte[INT_64_BYTES]; byte[] period = new byte[INT_64_BYTES];
@@ -171,34 +175,36 @@ class TransportCryptoImpl implements TransportCrypto {
long elapsed = timePeriod - k.getTimePeriod(); long elapsed = timePeriod - k.getTimePeriod();
TransportId t = k.getTransportId(); TransportId t = k.getTransportId();
SecretKey rootKey = k.getRootKey(); SecretKey rootKey = k.getRootKey();
boolean alice = k.isAlice(); boolean weAreAlice = k.isAlice();
if (elapsed <= 0) { if (elapsed <= 0) {
// The keys are for the given period or later - don't update them // The keys are for the given period or later - don't update them
return k; return k;
} else if (elapsed == 1) { } 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 inPrev = k.getCurrentIncomingKeys();
IncomingKeys inCurr = k.getNextIncomingKeys(); IncomingKeys inCurr = k.getNextIncomingKeys();
IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey, IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey,
alice, timePeriod + 1); weAreAlice, timePeriod + 1);
OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey, OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey,
alice, timePeriod); weAreAlice, timePeriod);
return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr, return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr,
rootKey, alice); rootKey, weAreAlice);
} else if (elapsed == 2) { } 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 inPrev = k.getNextIncomingKeys();
IncomingKeys inCurr = deriveIncomingHandshakeKeys(t, rootKey, IncomingKeys inCurr = deriveIncomingHandshakeKeys(t, rootKey,
alice, timePeriod); weAreAlice, timePeriod);
IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey, IncomingKeys inNext = deriveIncomingHandshakeKeys(t, rootKey,
alice, timePeriod + 1); weAreAlice, timePeriod + 1);
OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey, OutgoingKeys outCurr = deriveOutgoingHandshakeKeys(t, rootKey,
alice, timePeriod); weAreAlice, timePeriod);
return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr, return new HandshakeKeys(t, inPrev, inCurr, inNext, outCurr,
rootKey, alice); rootKey, weAreAlice);
} else { } else {
// The keys are more than two periods old - derive fresh keys // The keys are more than two periods old - derive fresh keys
return deriveHandshakeKeys(t, rootKey, timePeriod, alice); return deriveHandshakeKeys(t, rootKey, timePeriod, weAreAlice);
} }
} }