Files
timelimit-server/src/function/dh/shared-secret.ts
T
2022-09-22 08:47:06 +02:00

101 lines
3.2 KiB
TypeScript

/*
* server component for the TimeLimit App
* Copyright (C) 2019 - 2022 Jonas Lochmann
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, version 3 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
import * as Sequelize from 'sequelize'
import { createPrivateKey, createPublicKey, diffieHellman } from 'crypto'
import { Database } from '../../database'
import { calculateExpireTime } from '../../database/devicedhkey'
import { isVersionId } from '../../util/token'
export async function getSharedSecret({
database, transaction, familyId, deviceId, keyId, otherPublicKey
}: {
database: Database
transaction: Sequelize.Transaction
familyId: string
deviceId: string
keyId: string
otherPublicKey: Buffer
}) {
if (!isVersionId(keyId)) throw new KeyNotFoundException('invalid key id')
const databaseKeyEntry = await database.deviceDhKey.findOne({
where: {
familyId,
deviceId,
version: keyId
},
transaction
})
if (!databaseKeyEntry) throw new KeyNotFoundException('private key not found')
if (databaseKeyEntry.expireAt === null) {
databaseKeyEntry.expireAt = calculateExpireTime(BigInt(Date.now())).toString(10)
await databaseKeyEntry.save({ transaction })
} else {
if (BigInt(databaseKeyEntry.expireAt) < BigInt(Date.now())) throw new KeyExpiredException()
}
const privateKey = (() => {
try {
return createPrivateKey({
key: databaseKeyEntry.privateKey,
format: 'der',
type: 'pkcs8'
})
} catch (ex) {
throw new MalformedPrivateKeyException()
}
})()
const decodedOtherPublicKey = (() => {
try {
return createPublicKey({
key: otherPublicKey,
format: 'der',
type: 'spki'
})
} catch (ex) {
throw new MalformedPublicKeyException()
}
})()
const sharedSecret = (() => {
try {
return diffieHellman({
privateKey,
publicKey: decodedOtherPublicKey
})
} catch (ex) {
throw new MalformedNoMatchingKeysException()
}
})()
return {
sharedSecret,
ownPublicKey: databaseKeyEntry.publicKey
}
}
export class SharedSecretException extends Error {}
class MalformedPrivateKeyException extends SharedSecretException { constructor() { super('private key') } }
class MalformedPublicKeyException extends SharedSecretException { constructor() { super('public key') } }
class MalformedNoMatchingKeysException extends SharedSecretException { constructor() { super('no matching keys') } }
class KeyExpiredException extends SharedSecretException { constructor() { super('key expired') } }
class KeyNotFoundException extends SharedSecretException { constructor(message: string) { super('key not found: ' + message) } }