Skip to content

Commit

Permalink
chore: add nip44 decryption in android
Browse files Browse the repository at this point in the history
  • Loading branch information
@im-adithya
im-adithya committed Jan 21, 2025
1 parent c71b201 commit 9493d88
Show file tree
Hide file tree
Showing 2 changed files with 148 additions and 11 deletions.
140 changes: 135 additions & 5 deletions assets/android/MessagingService.kt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,13 +19,18 @@ import java.nio.charset.Charset
import javax.crypto.Cipher
import javax.crypto.spec.IvParameterSpec
import javax.crypto.spec.SecretKeySpec
import java.io.ByteArrayOutputStream
import org.bouncycastle.crypto.engines.ChaCha7539Engine
import org.bouncycastle.crypto.params.KeyParameter
import org.bouncycastle.crypto.params.ParametersWithIV

class MessagingService : FirebaseMessagingService() {

data class WalletInfo(
val name: String,
val sharedSecret: String,
val id: Int
val id: Int,
val version: String = "0.0"
)

private fun getWalletInfo(context: Context, key: String): WalletInfo? {
Expand All @@ -37,7 +42,8 @@ class MessagingService : FirebaseMessagingService() {
WalletInfo(
name = walletJson.optString("name", "Alby Go"),
sharedSecret = walletJson.optString("sharedSecret", ""),
id = walletJson.optInt("id", -1)
id = walletJson.optInt("id", -1),
version = walletJson.optString("version", "0.0")
)
} catch (e: Exception) {
e.printStackTrace()
Expand Down Expand Up @@ -73,7 +79,7 @@ class MessagingService : FirebaseMessagingService() {
val sharedSecretBytes = hexStringToByteArray(walletInfo.sharedSecret)
val walletName = walletInfo.name

val decryptedContent = decrypt(encryptedContent, sharedSecretBytes) ?: return
val decryptedContent = decrypt(encryptedContent, sharedSecretBytes, walletInfo.version) ?: return

val json = try {
JSONObject(decryptedContent)
Expand Down Expand Up @@ -132,7 +138,15 @@ class MessagingService : FirebaseMessagingService() {
return sharedPreferences.getString("${key}_name", null)
}

private fun decrypt(content: String, key: ByteArray): String? {
private fun decrypt(content: String, key: ByteArray, version: String): String? {
return if (version == "1.0") {
decryptNip44(content, key)
} else {
decryptNip04(content, key)
}
}

private fun decryptNip04(content: String, key: ByteArray): String? {
val parts = content.split("?iv=")
if (parts.size < 2) {
return null
Expand All @@ -154,6 +168,122 @@ class MessagingService : FirebaseMessagingService() {
}
}

private fun decryptNip44(b64CiphertextWrapped: String, conversationKey: ByteArray): String? {
val decoded = try {
Base64.decode(b64CiphertextWrapped, Base64.DEFAULT)
} catch (e: Exception) {
return null
}

if (decoded.size < 99 || decoded.size > 65603) {
return null
}

if (decoded[0].toInt() != 2) {
return null
}

val nonce = decoded.copyOfRange(1, 33)
val ciphertext = decoded.copyOfRange(33, decoded.size - 32)
val givenMac = decoded.copyOfRange(decoded.size - 32, decoded.size)

val (cc20key, cc20nonce, hmacKey) = messageKeys(conversationKey, nonce)

val expectedMac = sha256Hmac(hmacKey, ciphertext, nonce)
if (expectedMac == null || !expectedMac.contentEquals(givenMac)) {
return null
}

val padded = chacha20(cc20key, cc20nonce, ciphertext) ?: return null
if (padded.size < 2) {
return null
}

val unpaddedLen = ((padded[0].toInt() and 0xFF) shl 8) or
(padded[1].toInt() and 0xFF)

if (unpaddedLen < 1 || unpaddedLen > 65535) {
return null
}

val requiredSize = 2 + calcPadding(unpaddedLen)
if (padded.size != requiredSize) {
return null
}

val messageBytes = padded.copyOfRange(2, 2 + unpaddedLen)
return String(messageBytes, Charsets.UTF_8)
}

private fun messageKeys(conversationKey: ByteArray, nonce: ByteArray): Triple<ByteArray, ByteArray, ByteArray> {
val hkdfBytes = hkdfExpandSha256(conversationKey, nonce, 32 + 12 + 32)
val cc20key = hkdfBytes.copyOfRange(0, 32)
val cc20nonce = hkdfBytes.copyOfRange(32, 32 + 12)
val hmacKey = hkdfBytes.copyOfRange(44, 44 + 32)
return Triple(cc20key, cc20nonce, hmacKey)
}

private fun chacha20(key: ByteArray, nonce: ByteArray, message: ByteArray): ByteArray? {
return try {
val engine = ChaCha7539Engine()
engine.init(true, ParametersWithIV(KeyParameter(key), nonce))

val output = ByteArray(message.size)
engine.processBytes(message, 0, message.size, output, 0)
output
} catch (e: Exception) {
e.printStackTrace()
null
}
}

private fun sha256Hmac(key: ByteArray, ciphertext: ByteArray, nonce: ByteArray): ByteArray? {
return try {
val mac = javax.crypto.Mac.getInstance("HmacSHA256")
val secretKey = SecretKeySpec(key, "HmacSHA256")
mac.init(secretKey)
mac.update(nonce)
mac.update(ciphertext)
mac.doFinal()
} catch (e: Exception) {
null
}
}

private fun calcPadding(msgSize: Int): Int {
if (msgSize <= 32) return 32

val s = msgSize - 1
val highestBit = 32 - Integer.numberOfLeadingZeros(s)
val nextPowTwo = 1 shl highestBit
val chunk = kotlin.math.max(32, nextPowTwo / 8)
val blocks = (s / chunk) + 1
return chunk * blocks
}

private fun hkdfExpandSha256(prk: ByteArray, info: ByteArray, outLen: Int): ByteArray {
val hashLen = 32
val n = (outLen + hashLen - 1) / hashLen
var t = ByteArray(0)
val okm = ByteArrayOutputStream()

for (i in 1..n) {
val mac = javax.crypto.Mac.getInstance("HmacSHA256")
val keySpec = SecretKeySpec(prk, "HmacSHA256")
mac.init(keySpec)

mac.update(t)
mac.update(info)
mac.update(i.toByte())

t = mac.doFinal()
okm.write(t)
}

val result = okm.toByteArray()
return if (result.size > outLen) result.copyOf(outLen) else result
}

private fun hexStringToByteArray(s: String): ByteArray {
val len = s.length
val data = ByteArray(len / 2)
Expand All @@ -165,7 +295,7 @@ class MessagingService : FirebaseMessagingService() {
}
return data
}

// private fun wakeApp() {
// @Suppress("DEPRECATION")
// val pm = applicationContext.getSystemService(POWER_SERVICE) as PowerManager
Expand Down
19 changes: 13 additions & 6 deletions plugins/android/withMessageServicePlugin.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -92,15 +92,22 @@ function modifyAndroidManifest(config) {
}

function modifyAppBuildGradle(config) {
const buildGradle = config.modResults.contents;
const dependency = `implementation("com.google.firebase:firebase-messaging:23.2.1")`;
let buildGradle = config.modResults.contents;
const firebaseDependency = `implementation("com.google.firebase:firebase-messaging:23.2.1")`;

if (!buildGradle.includes(dependency)) {
const pattern = /dependencies\s?{/;
config.modResults.contents = buildGradle.replace(pattern, (match) => {
return `${match}\n ${dependency}`;
if (!buildGradle.includes(firebaseDependency)) {
buildGradle = buildGradle.replace(/dependencies\s?{/, (match) => {
return `${match}\n ${firebaseDependency}`;
});
}

const bcDependency = `implementation("org.bouncycastle:bcprov-jdk15to18:1.76")`;
if (!buildGradle.includes(bcDependency)) {
buildGradle = buildGradle.replace(/dependencies\s?{/, (match) => {
return `${match}\n ${bcDependency}`;
});
}

config.modResults.contents = buildGradle;
return config;
}

0 comments on commit 9493d88

Please sign in to comment.