mirror of
https://github.com/vitorpamplona/amethyst.git
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refactor(geohash-chat): own the anonymous identity on Account
Replace the standalone GeohashChatIdentity object with an account-owned GeohashChatIdentityState (account.geohashIdentity), so the throwaway per-geohash identities are scoped to a single account and cached per cell. This also fixes a cross-account privacy leak: the old DeviceSeed fallback (used by bunker / external signers that can't reach a raw key) stored one seed under a single global preference key, so every account on the device shared it — producing identical throwaway identities and linking a user's alt accounts together in every cell. The seed now lives in the account's own encrypted store (keyed by pubkey), so different accounts get different seeds. Local-key accounts are unchanged: their identity is still derived from the account private key and stays stable across devices. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0172JoMccseEKenyWan6txWV
This commit is contained in:
Claude
@@ -573,6 +573,9 @@ class Account(
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val geohashListDecryptionCache = GeohashListDecryptionCache(signer)
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val geohashList = GeohashListState(signer, cache, geohashListDecryptionCache, scope, settings)
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// Anonymous, per-geohash throwaway identities for Bitchat-interoperable location chats.
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val geohashIdentity = GeohashChatIdentityState(signer)
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val muteListDecryptionCache = MuteListDecryptionCache(signer)
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val muteList = MuteListState(signer, cache, muteListDecryptionCache, scope, settings)
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@@ -0,0 +1,94 @@
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/*
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* Copyright (c) 2025 Vitor Pamplona
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
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* Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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package com.vitorpamplona.amethyst.model
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import androidx.core.content.edit
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import com.vitorpamplona.amethyst.Amethyst
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import com.vitorpamplona.quartz.experimental.bitchat.identity.GeohashKeyDerivation
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import com.vitorpamplona.quartz.nip01Core.core.hexToByteArray
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import com.vitorpamplona.quartz.nip01Core.core.toHexKey
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import com.vitorpamplona.quartz.nip01Core.crypto.KeyPair
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import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
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import com.vitorpamplona.quartz.nip01Core.signers.NostrSignerInternal
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import com.vitorpamplona.quartz.utils.RandomInstance
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/**
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* The account's anonymous, per-geohash chat identities.
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*
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* Geohash channels are location-tagged, so posting under the account's real npub
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* would publish the user's movements tied to their public identity. Instead each
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* cell gets a throwaway key that is unlinkable to the npub (and to the user's key
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* in every other cell). This state object caches the derived keys and owns the
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* seed they come from, keyed to a single account — so switching accounts (or
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* logging out) switches identities with it.
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*
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* The seed is chosen per signer:
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* - **Local key account** → derived from the account private key
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* ([GeohashKeyDerivation.accountSeed]). Stable across all of the user's devices
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* and recoverable from the account, while staying publicly unlinkable.
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* - **Remote (NIP-46) / external (NIP-55) signer** → the raw key is unreachable,
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* so a random 32-byte seed is kept in this account's encrypted storage. Because
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* the store is scoped to the account's pubkey, two accounts on one device get
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* different seeds (a global seed would have made their throwaway identities
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* collide, linking the accounts in every cell).
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*/
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class GeohashChatIdentityState(
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private val signer: NostrSigner,
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) {
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private val lock = Any()
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private val cache = HashMap<String, KeyPair>()
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@Volatile private var cachedDeviceSeed: ByteArray? = null
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/** The Nostr key pair to use inside [geohash]. Derivation is cheap but cached; call off the main thread. */
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fun keyPair(geohash: String): KeyPair =
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synchronized(lock) {
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cache.getOrPut(geohash) { GeohashKeyDerivation.deriveKeyPair(seed(), geohash) }
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}
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private fun seed(): ByteArray = accountPrivKey()?.let { GeohashKeyDerivation.accountSeed(it) } ?: deviceSeed()
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private fun accountPrivKey(): ByteArray? = (signer as? NostrSignerInternal)?.keyPair?.privKey
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/** Random per-account seed, used only when the account key is unreachable (bunker / external signer). */
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private fun deviceSeed(): ByteArray {
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cachedDeviceSeed?.let { return it }
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synchronized(lock) {
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cachedDeviceSeed?.let { return it }
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val prefs = Amethyst.instance.encryptedStorage(signer.pubKey)
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val existing = prefs.getString(PREF_KEY, null)
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val seed =
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if (existing != null && existing.length == GeohashKeyDerivation.SEED_SIZE * 2) {
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existing.hexToByteArray()
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} else {
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val fresh = RandomInstance.bytes(GeohashKeyDerivation.SEED_SIZE)
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prefs.edit { putString(PREF_KEY, fresh.toHexKey()) }
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fresh
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}
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cachedDeviceSeed = seed
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return seed
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}
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}
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companion object {
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private const val PREF_KEY = "geohash_chat_device_seed"
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}
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}
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-92
@@ -1,92 +0,0 @@
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/*
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* Copyright (c) 2025 Vitor Pamplona
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
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* Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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package com.vitorpamplona.amethyst.service.geohash
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import androidx.core.content.edit
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import com.vitorpamplona.amethyst.Amethyst
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import com.vitorpamplona.amethyst.model.Account
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import com.vitorpamplona.quartz.experimental.bitchat.identity.GeohashKeyDerivation
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import com.vitorpamplona.quartz.nip01Core.core.hexToByteArray
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import com.vitorpamplona.quartz.nip01Core.core.toHexKey
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import com.vitorpamplona.quartz.nip01Core.crypto.KeyPair
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import com.vitorpamplona.quartz.nip01Core.signers.NostrSignerInternal
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import com.vitorpamplona.quartz.utils.RandomInstance
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/**
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* Resolves the anonymous, per-geohash chat identity for the current user.
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*
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* Geohash channels are location-tagged, so posting under the account's real npub
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* would publish the user's movements tied to their public identity. Instead each
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* cell gets a throwaway key that is unlinkable to the npub (and to the user's key
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* in other cells).
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*
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* The seed those keys derive from is chosen per signer:
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* - **Local key account** → derived from the account private key
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* ([GeohashKeyDerivation.accountSeed]). The identity is then stable across all
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* of the user's devices and recoverable from the account, while staying
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* publicly unlinkable.
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* - **Remote (NIP-46) / external (NIP-55) signer** → we can't reach the raw key,
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* so we fall back to [DeviceSeed]: a random 32-byte seed kept in the app's
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* global encrypted storage (per-device, generated once).
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*/
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object GeohashChatIdentity {
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/** The Nostr key pair to use inside [geohash] for [account]. Call off the main thread. */
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fun keyPair(
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account: Account,
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geohash: String,
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): KeyPair {
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val seed =
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accountPrivKey(account)?.let { GeohashKeyDerivation.accountSeed(it) }
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?: DeviceSeed.seed()
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return GeohashKeyDerivation.deriveKeyPair(seed, geohash)
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}
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private fun accountPrivKey(account: Account): ByteArray? = (account.signer as? NostrSignerInternal)?.keyPair?.privKey
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/**
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* Fallback random device seed, used only when the account key is unreachable
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* (bunker / external signer).
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*/
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object DeviceSeed {
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private const val PREF_KEY = "geohash_chat_device_seed"
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@Volatile private var cached: ByteArray? = null
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fun seed(): ByteArray {
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cached?.let { return it }
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synchronized(this) {
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cached?.let { return it }
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val prefs = Amethyst.instance.encryptedStorage()
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val existing = prefs.getString(PREF_KEY, null)
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val seed =
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if (existing != null && existing.length == GeohashKeyDerivation.SEED_SIZE * 2) {
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existing.hexToByteArray()
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} else {
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val fresh = RandomInstance.bytes(GeohashKeyDerivation.SEED_SIZE)
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prefs.edit { putString(PREF_KEY, fresh.toHexKey()) }
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fresh
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}
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cached = seed
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return seed
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}
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}
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}
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}
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+9
-4
@@ -22,7 +22,6 @@ package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.geohashChat
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import androidx.lifecycle.ViewModel
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import androidx.lifecycle.viewModelScope
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import com.vitorpamplona.amethyst.service.geohash.GeohashChatIdentity
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import com.vitorpamplona.amethyst.service.geohash.GeohashRelays
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import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
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import com.vitorpamplona.quartz.experimental.bitchat.geohash.GeohashChatEvent
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@@ -103,7 +102,13 @@ class GeohashChatViewModel : ViewModel() {
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}
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private suspend fun start() {
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_myPubKey.value = withContext(Dispatchers.IO) { GeohashChatIdentity.keyPair(accountViewModel.account, geohash).pubKey.toHexKey() }
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_myPubKey.value =
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withContext(Dispatchers.IO) {
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accountViewModel.account.geohashIdentity
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.keyPair(geohash)
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.pubKey
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.toHexKey()
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}
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_relays.value = resolveRelays()
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}
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@@ -127,7 +132,7 @@ class GeohashChatViewModel : ViewModel() {
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signer = account.signer
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pubKeyHex = account.signer.pubKey
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} else {
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val keyPair = withContext(Dispatchers.IO) { GeohashChatIdentity.keyPair(account, geohash) }
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val keyPair = withContext(Dispatchers.IO) { account.geohashIdentity.keyPair(geohash) }
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signer = NostrSignerInternal(keyPair)
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pubKeyHex = keyPair.pubKey.toHexKey()
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}
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@@ -150,7 +155,7 @@ class GeohashChatViewModel : ViewModel() {
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viewModelScope.launch {
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val relays = _relays.value.toSet().ifEmpty { resolveRelays().toSet() }
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if (relays.isEmpty()) return@launch
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val keyPair = withContext(Dispatchers.IO) { GeohashChatIdentity.keyPair(accountViewModel.account, geohash) }
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val keyPair = withContext(Dispatchers.IO) { accountViewModel.account.geohashIdentity.keyPair(geohash) }
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val signer = NostrSignerInternal(keyPair)
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val template = GeohashPresenceEvent.build(geohash, nickname = nickname?.ifBlank { null })
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runCatching { accountViewModel.account.signWithAndSendPrivately(template, signer, relays) }
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