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Always reset all ratchets if someone leaves or is kicked

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pull/218/head
nielsandriesse 4 years ago
parent d3212b70d6
commit a572761432
2 changed files with 50 additions and 73 deletions
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112
SignalServiceKit/src/Loki/Protocol/Closed Groups/ClosedGroupsProtocol.swift
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@ -14,7 +14,6 @@ import PromiseKit
public final class ClosedGroupsProtocol : NSObject {
// TODO:
// • Always reset all ratchets if someone leaves or is kicked?
// • Multi device
// • ClosedGroupsProtocol
// • SyncMessagesProtocol
@ -23,6 +22,7 @@ public final class ClosedGroupsProtocol : NSObject {
/// the message sending pipeline making a request for each member.
public static func createClosedGroup(name: String, members membersAsSet: Set<String>, transaction: YapDatabaseReadWriteTransaction) -> TSGroupThread {
var membersAsSet = membersAsSet
let messageSenderJobQueue = SSKEnvironment.shared.messageSenderJobQueue
let userPublicKey = getUserHexEncodedPublicKey()
// Generate a key pair for the group
let groupKeyPair = Curve25519.generateKeyPair()
@ -53,7 +53,6 @@ public final class ClosedGroupsProtocol : NSObject {
thread.save(with: transaction)
let closedGroupUpdateMessageKind = ClosedGroupUpdateMessage.Kind.new(groupPublicKey: Data(hex: groupPublicKey), name: name, groupPrivateKey: groupKeyPair.privateKey, senderKeys: senderKeys, members: members, admins: admins)
let closedGroupUpdateMessage = ClosedGroupUpdateMessage(thread: thread, kind: closedGroupUpdateMessageKind)
let messageSenderJobQueue = SSKEnvironment.shared.messageSenderJobQueue
messageSenderJobQueue.add(message: closedGroupUpdateMessage, transaction: transaction)
}
// Add the group to the user's set of public keys to poll for
@ -75,6 +74,9 @@ public final class ClosedGroupsProtocol : NSObject {
let group = thread.groupModel
let name = group.groupName!
let admins = group.groupAdminIds
guard let groupPrivateKey = Storage.getClosedGroupPrivateKey(for: groupPublicKey) else {
return print("[Loki] Can't get private key for closed group.")
}
// Add the members to the member list
var members = group.groupMemberIds
members.append(contentsOf: newMembersAsSet)
@ -93,13 +95,13 @@ public final class ClosedGroupsProtocol : NSObject {
let closedGroupUpdateMessage = ClosedGroupUpdateMessage(thread: thread, kind: closedGroupUpdateMessageKind)
messageSenderJobQueue.add(message: closedGroupUpdateMessage, transaction: transaction)
// Send closed group update messages to the new members using established channels
let allSenderKeys = Storage.getAllClosedGroupRatchets(for: groupPublicKey).map {
let allSenderKeys = Storage.getAllClosedGroupRatchets(for: groupPublicKey).map { // This includes the newly generated ratchets
ClosedGroupSenderKey(chainKey: Data(hex: $0.chainKey), keyIndex: $0.keyIndex)
}
for member in newMembers {
let closedGroupUpdateMessageKind = ClosedGroupUpdateMessage.Kind.info(groupPublicKey: Data(hex: groupPublicKey), name: name, senderKeys: allSenderKeys, members: members, admins: admins)
let thread = TSContactThread.getOrCreateThread(contactId: member)
thread.save(with: transaction)
let closedGroupUpdateMessageKind = ClosedGroupUpdateMessage.Kind.new(groupPublicKey: Data(hex: groupPublicKey), name: name, groupPrivateKey: Data(hex: groupPrivateKey), senderKeys: allSenderKeys, members: members, admins: admins)
let closedGroupUpdateMessage = ClosedGroupUpdateMessage(thread: thread, kind: closedGroupUpdateMessageKind)
messageSenderJobQueue.add(message: closedGroupUpdateMessage, transaction: transaction)
}
@ -112,7 +114,16 @@ public final class ClosedGroupsProtocol : NSObject {
infoMessage.save(with: transaction)
}
public static func removeMembers(_ membersToRemoveAsSet: Set<String>, from groupPublicKey: String, using transaction: YapDatabaseReadWriteTransaction) {
public static func leave(_ groupPublicKey: String, using transaction: YapDatabaseReadWriteTransaction) {
removeMembers([ getUserHexEncodedPublicKey() ], from: groupPublicKey, using: transaction)
}
public static func removeMembers(_ membersToRemove: Set<String>, from groupPublicKey: String, using transaction: YapDatabaseReadWriteTransaction) {
let userPublicKey = getUserHexEncodedPublicKey()
let isUserLeaving = membersToRemove.contains(userPublicKey)
guard !isUserLeaving || membersToRemove.count == 1 else {
return print("[Loki] Can't remove self and others simultaneously.")
}
// Prepare
let messageSenderJobQueue = SSKEnvironment.shared.messageSenderJobQueue
let groupID = LKGroupUtilities.getEncodedClosedGroupID(groupPublicKey)
@ -124,73 +135,43 @@ public final class ClosedGroupsProtocol : NSObject {
let admins = group.groupAdminIds
// Remove the members from the member list
var members = group.groupMemberIds
let indexes = membersToRemoveAsSet.compactMap { members.firstIndex(of: $0) }
guard indexes.count == membersToRemoveAsSet.count else {
let indexes = membersToRemove.compactMap { members.firstIndex(of: $0) }
guard indexes.count == membersToRemove.count else {
return print("[Loki] Can't remove users from group.")
}
indexes.forEach { members.remove(at: $0) }
// Establish sessions if needed (shouldn't be necessary under normal circumstances as
// sessions would've already been established previously)
establishSessionsIfNeeded(with: group.groupMemberIds, using: transaction) // Intentionally not `members`
// Send a closed group update message to the removed members (this message is aimed at the group)
// Send the update to the group (don't include new ratchets as everyone should generate new ratchets individually)
let closedGroupUpdateMessageKind = ClosedGroupUpdateMessage.Kind.info(groupPublicKey: Data(hex: groupPublicKey), name: name, senderKeys: [], members: members, admins: admins)
let closedGroupUpdateMessage = ClosedGroupUpdateMessage(thread: thread, kind: closedGroupUpdateMessageKind)
messageSenderJobQueue.add(message: closedGroupUpdateMessage, transaction: transaction)
// Generate new ratchets for everyone except the members that were removed (it's important that
// this happens after the code above)
let ratchets = members.map {
SharedSenderKeysImplementation.shared.generateRatchet(for: groupPublicKey, senderPublicKey: $0, using: transaction)
}
// Send a closed group update message to all members (minus the ones that were removed) with everyone's new
// ratchets using established channels
let senderKeys = ratchets.map { ClosedGroupSenderKey(chainKey: Data(hex: $0.chainKey), keyIndex: $0.keyIndex) }
for member in members {
let thread = TSContactThread.getOrCreateThread(withContactId: member, transaction: transaction)
thread.save(with: transaction)
let closedGroupUpdateMessageKind = ClosedGroupUpdateMessage.Kind.info(groupPublicKey: Data(hex: groupPublicKey), name: name, senderKeys: senderKeys, members: members, admins: admins)
let closedGroupUpdateMessage = ClosedGroupUpdateMessage(thread: thread, kind: closedGroupUpdateMessageKind)
messageSenderJobQueue.add(message: closedGroupUpdateMessage, transaction: transaction)
}
// Update the group
let groupIDAsData = groupID.data(using: String.Encoding.utf8)!
let newGroupModel = TSGroupModel(title: name, memberIds: members, image: nil, groupId: groupIDAsData, groupType: .closedGroup, adminIds: admins)
thread.setGroupModel(newGroupModel, with: transaction)
// Notify the user
let infoMessage = TSInfoMessage(timestamp: NSDate.ows_millisecondTimeStamp(), in: thread, messageType: .typeGroupUpdate)
infoMessage.save(with: transaction)
}
public static func leave(_ groupPublicKey: String, using transaction: YapDatabaseReadWriteTransaction) {
// Prepare
let groupID = LKGroupUtilities.getEncodedClosedGroupID(groupPublicKey)
guard let thread = TSGroupThread.fetch(uniqueId: groupID, transaction: transaction) else {
return print("[Loki] Can't leave nonexistent closed group.")
}
let group = thread.groupModel
let name = group.groupName!
let admins = group.groupAdminIds
// Remove the user from the member list
var members = group.groupMemberIds
guard let indexOfUser = members.firstIndex(of: getUserHexEncodedPublicKey()) else {
return print("[Loki] Can't leave group.")
}
members.remove(at: indexOfUser)
// Send the update to the group (don't include new ratchets as everyone should generate new ratchets
// individually in this case)
let closedGroupUpdateMessageKind = ClosedGroupUpdateMessage.Kind.info(groupPublicKey: Data(hex: groupPublicKey), name: name, senderKeys: [], members: members, admins: admins)
let closedGroupUpdateMessage = ClosedGroupUpdateMessage(thread: thread, kind: closedGroupUpdateMessageKind)
let messageSenderJobQueue = SSKEnvironment.shared.messageSenderJobQueue
messageSenderJobQueue.add(message: closedGroupUpdateMessage, transaction: transaction)
// Delete all ratchets (it's important that this happens after the code above)
// Delete all ratchets (it's important that this happens after sending out the update)
Storage.removeAllClosedGroupRatchets(for: groupPublicKey, using: transaction)
// Remove the group from the user's set of public keys to poll for
Storage.removeClosedGroupPrivateKey(for: groupPublicKey, using: transaction)
// Remove the group from the user's set of public keys to poll for if the user is leaving. Otherwise generate
// a new ratchet and send it out to all members (minus the removed ones) using established channels.
if isUserLeaving {
Storage.removeClosedGroupPrivateKey(for: groupPublicKey, using: transaction)
} else {
// Establish sessions if needed (shouldn't be necessary under normal circumstances as
// sessions would've already been established previously)
establishSessionsIfNeeded(with: members, using: transaction)
// Send out the user's new ratchet to all members (minus the removed ones) using established channels
let newRatchet = SharedSenderKeysImplementation.shared.generateRatchet(for: groupPublicKey, senderPublicKey: userPublicKey, using: transaction)
let newSenderKey = ClosedGroupSenderKey(chainKey: Data(hex: newRatchet.chainKey), keyIndex: newRatchet.keyIndex)
for member in members {
let thread = TSContactThread.getOrCreateThread(withContactId: member, transaction: transaction)
thread.save(with: transaction)
let closedGroupUpdateMessageKind = ClosedGroupUpdateMessage.Kind.senderKey(groupPublicKey: Data(hex: groupPublicKey), senderKey: newSenderKey)
let closedGroupUpdateMessage = ClosedGroupUpdateMessage(thread: thread, kind: closedGroupUpdateMessageKind)
messageSenderJobQueue.add(message: closedGroupUpdateMessage, transaction: transaction)
}
}
// Update the group
let groupIDAsData = groupID.data(using: String.Encoding.utf8)!
let newGroupModel = TSGroupModel(title: name, memberIds: members, image: nil, groupId: groupIDAsData, groupType: .closedGroup, adminIds: admins)
thread.setGroupModel(newGroupModel, with: transaction)
// Notify the user
let infoMessage = TSInfoMessage(timestamp: NSDate.ows_millisecondTimeStamp(), in: thread, messageType: .typeGroupUpdate)
let infoMessageType: TSInfoMessageType = isUserLeaving ? .typeGroupQuit : .typeGroupUpdate
let infoMessage = TSInfoMessage(timestamp: NSDate.ows_millisecondTimeStamp(), in: thread, messageType: infoMessageType)
infoMessage.save(with: transaction)
}
@ -253,7 +234,7 @@ public final class ClosedGroupsProtocol : NSObject {
// Check that the sender is an admin (before the update)
var isSenderAdmin = false
Storage.read { transaction in
isSenderAdmin = !thread.isUserAdmin(inGroup: senderPublicKey, transaction: transaction) // TODO: Validate that `senderPublicKey` here isn't the group public key
isSenderAdmin = !thread.isUserAdmin(inGroup: senderPublicKey, transaction: transaction)
}
guard isSenderAdmin else {
return print("[Loki] Ignoring closed group update from non-admin.")
@ -261,7 +242,7 @@ public final class ClosedGroupsProtocol : NSObject {
// Establish sessions if needed (it's important that this happens before the code below)
establishSessionsIfNeeded(with: members, using: transaction)
// Parse out any new members and store their ratchets (it's important that
// this happens before handling removed members)
// this happens before the code below)
let oldMembers = group.groupMemberIds
let newMembers = members.filter { !oldMembers.contains($0) }
if newMembers.count == senderKeys.count { // If someone left or was kicked the message won't have any sender keys
@ -275,13 +256,12 @@ public final class ClosedGroupsProtocol : NSObject {
if Set(members).intersection(oldMembers) != Set(oldMembers) {
Storage.removeAllClosedGroupRatchets(for: groupPublicKey, using: transaction)
let userPublicKey = getUserHexEncodedPublicKey()
let newRatchet = SharedSenderKeysImplementation.shared.generateRatchet(for: groupPublicKey, senderPublicKey: userPublicKey, using: transaction)
let newSenderKey = ClosedGroupSenderKey(chainKey: Data(hex: newRatchet.chainKey), keyIndex: newRatchet.keyIndex)
Storage.setClosedGroupRatchet(for: groupPublicKey, senderPublicKey: userPublicKey, ratchet: newRatchet, using: transaction)
let userRatchet = SharedSenderKeysImplementation.shared.generateRatchet(for: groupPublicKey, senderPublicKey: userPublicKey, using: transaction)
let userSenderKey = ClosedGroupSenderKey(chainKey: Data(hex: userRatchet.chainKey), keyIndex: userRatchet.keyIndex)
for member in members {
let thread = TSContactThread.getOrCreateThread(withContactId: member, transaction: transaction)
thread.save(with: transaction)
let closedGroupUpdateMessageKind = ClosedGroupUpdateMessage.Kind.senderKey(groupPublicKey: Data(hex: groupPublicKey), senderKey: newSenderKey)
let closedGroupUpdateMessageKind = ClosedGroupUpdateMessage.Kind.senderKey(groupPublicKey: Data(hex: groupPublicKey), senderKey: userSenderKey)
let closedGroupUpdateMessage = ClosedGroupUpdateMessage(thread: thread, kind: closedGroupUpdateMessageKind)
let messageSenderJobQueue = SSKEnvironment.shared.messageSenderJobQueue
messageSenderJobQueue.add(message: closedGroupUpdateMessage, transaction: transaction)

11
SignalServiceKit/src/Loki/Protocol/Closed Groups/SharedSenderKeysImplementation.swift
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@ -10,11 +10,11 @@ public final class SharedSenderKeysImplementation : NSObject, SharedSenderKeysPr
// MARK: Documentation
// A quick overview of how shared sender key based closed groups work:
//
// • When a user creates the group, they generate a key pair for the group along with a ratchet for
// • When a user creates a group, they generate a key pair for the group along with a ratchet for
// every member of the group. They bundle this together with some other group info such as the group
// name in a `ClosedGroupUpdateMessage` and send that using established channels to every member of
// the group. Note that because a user can only pick from their existing contacts when selecting
// the group members they don't need to establish sessions before being able to send the
// the group members they shouldn't need to establish sessions before being able to send the
// `ClosedGroupUpdateMessage`. Another way to optimize the performance of the group creation process
// is to batch fetch the device links of all members involved ahead of time, rather than letting
// the sending pipeline do it separately for every user the `ClosedGroupUpdateMessage` is sent to.
@ -25,8 +25,8 @@ public final class SharedSenderKeysImplementation : NSObject, SharedSenderKeysPr
// the message.
// • When another user receives that message, they step the ratchet associated with the sender and
// use the resulting message key to decrypt the message.
// • When a user leaves the group, new ratchets must be generated for all members to ensure that the
// user that left can't decrypt messages going forward. To this end every user deletes all ratchets
// • When a user leaves or is kicked from a group, all members must generate new ratchets to ensure that
// removed users can't decrypt messages going forward. To this end every user deletes all ratchets
// associated with the group in question upon receiving a group update message that indicates that
// a user left. They then generate a new ratchet for themselves and send it out to all members of
// the group (again fetching device links ahead of time). The user should already have established
@ -35,9 +35,6 @@ public final class SharedSenderKeysImplementation : NSObject, SharedSenderKeysPr
// send that bundled in a `ClosedGroupUpdateMessage` to the group. They send a
// `ClosedGroupUpdateMessage` with the newly generated ratchet but also the existing ratchets of
// every other member of the group to the user that joined.
// • When a user kicks a member from the group, they re-generate ratchets for everyone and send
// those out to all members (minus the member that was just kicked) in a
// `ClosedGroupUpdateMessage` using established channels.
// MARK: Ratcheting Error
public enum RatchetingError : LocalizedError {

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