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crypto: Remove the one-time keys uploader

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Damir Jelić 2021-03-24 16:00:51 +01:00
parent 555d24fea5
commit 629623f720
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matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/OneTimeKeysUploader.kt
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/*
* Copyright 2020 The Matrix.org Foundation C.I.C.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.matrix.android.sdk.internal.crypto
import org.matrix.android.sdk.internal.crypto.model.MXKey
import org.matrix.android.sdk.internal.crypto.model.rest.KeysUploadResponse
import org.matrix.android.sdk.internal.crypto.tasks.UploadKeysTask
import org.matrix.android.sdk.internal.session.SessionScope
import org.matrix.android.sdk.internal.util.JsonCanonicalizer
import org.matrix.olm.OlmAccount
import timber.log.Timber
import javax.inject.Inject
import kotlin.math.floor
import kotlin.math.min
@SessionScope
internal class OneTimeKeysUploader @Inject constructor(
private val olmDevice: MXOlmDevice,
private val objectSigner: ObjectSigner,
private val uploadKeysTask: UploadKeysTask
) {
// tell if there is a OTK check in progress
private var oneTimeKeyCheckInProgress = false
// last OTK check timestamp
private var lastOneTimeKeyCheck: Long = 0
private var oneTimeKeyCount: Int? = null
/**
* Stores the current one_time_key count which will be handled later (in a call of
* _onSyncCompleted). The count is e.g. coming from a /sync response.
*
* @param currentCount the new count
*/
fun updateOneTimeKeyCount(currentCount: Int) {
oneTimeKeyCount = currentCount
}
/**
* Check if the OTK must be uploaded.
*/
suspend fun maybeUploadOneTimeKeys() {
if (oneTimeKeyCheckInProgress) {
Timber.v("maybeUploadOneTimeKeys: already in progress")
return
}
if (System.currentTimeMillis() - lastOneTimeKeyCheck < ONE_TIME_KEY_UPLOAD_PERIOD) {
// we've done a key upload recently.
Timber.v("maybeUploadOneTimeKeys: executed too recently")
return
}
lastOneTimeKeyCheck = System.currentTimeMillis()
oneTimeKeyCheckInProgress = true
// We then check how many keys we can store in the Account object.
val maxOneTimeKeys = olmDevice.getMaxNumberOfOneTimeKeys()
// Try to keep at most half that number on the server. This leaves the
// rest of the slots free to hold keys that have been claimed from the
// server but we haven't received a message for.
// If we run out of slots when generating new keys then olm will
// discard the oldest private keys first. This will eventually clean
// out stale private keys that won't receive a message.
val keyLimit = floor(maxOneTimeKeys / 2.0).toInt()
val oneTimeKeyCountFromSync = oneTimeKeyCount
if (oneTimeKeyCountFromSync != null) {
// We need to keep a pool of one time public keys on the server so that
// other devices can start conversations with us. But we can only store
// a finite number of private keys in the olm Account object.
// To complicate things further then can be a delay between a device
// claiming a public one time key from the server and it sending us a
// message. We need to keep the corresponding private key locally until
// we receive the message.
// But that message might never arrive leaving us stuck with duff
// private keys clogging up our local storage.
// So we need some kind of engineering compromise to balance all of
// these factors.
try {
val uploadedKeys = uploadOTK(oneTimeKeyCountFromSync, keyLimit)
Timber.v("## uploadKeys() : success, $uploadedKeys key(s) sent")
} finally {
oneTimeKeyCheckInProgress = false
}
} else {
Timber.w("maybeUploadOneTimeKeys: waiting to know the number of OTK from the sync")
oneTimeKeyCheckInProgress = false
lastOneTimeKeyCheck = 0
}
}
/**
* Upload some the OTKs.
*
* @param keyCount the key count
* @param keyLimit the limit
* @return the number of uploaded keys
*/
private suspend fun uploadOTK(keyCount: Int, keyLimit: Int): Int {
if (keyLimit <= keyCount) {
// If we don't need to generate any more keys then we are done.
return 0
}
val keysThisLoop = min(keyLimit - keyCount, ONE_TIME_KEY_GENERATION_MAX_NUMBER)
olmDevice.generateOneTimeKeys(keysThisLoop)
val response = uploadOneTimeKeys(olmDevice.getOneTimeKeys())
olmDevice.markKeysAsPublished()
if (response.hasOneTimeKeyCountsForAlgorithm(MXKey.KEY_SIGNED_CURVE_25519_TYPE)) {
// Maybe upload other keys
return keysThisLoop + uploadOTK(response.oneTimeKeyCountsForAlgorithm(MXKey.KEY_SIGNED_CURVE_25519_TYPE), keyLimit)
} else {
Timber.e("## uploadOTK() : response for uploading keys does not contain one_time_key_counts.signed_curve25519")
throw Exception("response for uploading keys does not contain one_time_key_counts.signed_curve25519")
}
}
/**
* Upload curve25519 one time keys.
*/
private suspend fun uploadOneTimeKeys(oneTimeKeys: Map<String, Map<String, String>>?): KeysUploadResponse {
val oneTimeJson = mutableMapOf<String, Any>()
val curve25519Map = oneTimeKeys?.get(OlmAccount.JSON_KEY_ONE_TIME_KEY).orEmpty()
curve25519Map.forEach { (key_id, value) ->
val k = mutableMapOf<String, Any>()
k["key"] = value
// the key is also signed
val canonicalJson = JsonCanonicalizer.getCanonicalJson(Map::class.java, k)
k["signatures"] = objectSigner.signObject(canonicalJson)
oneTimeJson["signed_curve25519:$key_id"] = k
}
// For now, we set the device id explicitly, as we may not be using the
// same one as used in login.
val uploadParams = UploadKeysTask.Params(null, oneTimeJson)
return uploadKeysTask.execute(uploadParams)
}
companion object {
// max number of keys to upload at once
// Creating keys can be an expensive operation so we limit the
// number we generate in one go to avoid blocking the application
// for too long.
private const val ONE_TIME_KEY_GENERATION_MAX_NUMBER = 5
// frequency with which to check & upload one-time keys
private const val ONE_TIME_KEY_UPLOAD_PERIOD = (60 * 1000).toLong() // one minute
}
}