init

app/src/main/java/com/bitchat/android/BitchatApplication.kt

@@ -0,0 +1,16 @@
+package com.bitchat.android
+
+import android.app.Application
+
+/**
+ * Main application class for bitchat Android
+ */
+class BitchatApplication : Application() {
+    
+    override fun onCreate() {
+        super.onCreate()
+        
+        // Initialize any global services or configurations
+        // For now, keep it simple
+    }
+}

app/src/main/java/com/bitchat/android/MainActivity.kt

@@ -0,0 +1,97 @@
+package com.bitchat.android
+
+import android.Manifest
+import android.os.Bundle
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.setContent
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.activity.viewModels
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Surface
+import androidx.compose.runtime.*
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+import com.bitchat.android.ui.ChatScreen
+import com.bitchat.android.ui.ChatViewModel
+import com.bitchat.android.ui.theme.BitchatTheme
+
+class MainActivity : ComponentActivity() {
+    
+    private val chatViewModel: ChatViewModel by viewModels()
+    
+    private val permissionLauncher = registerForActivityResult(
+        ActivityResultContracts.RequestMultiplePermissions()
+    ) { permissions ->
+        val allPermissionsGranted = permissions.values.all { it }
+        if (allPermissionsGranted) {
+            // Permissions granted, the mesh service should start automatically
+        } else {
+            // Handle permission denial
+            finish()
+        }
+    }
+    
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        
+        // Request necessary permissions
+        requestPermissions()
+        
+        setContent {
+            BitchatTheme {
+                Surface(
+                    modifier = Modifier.fillMaxSize(),
+                    color = MaterialTheme.colorScheme.background
+                ) {
+                    ChatScreen(viewModel = chatViewModel)
+                }
+            }
+        }
+    }
+    
+    private fun requestPermissions() {
+        val permissions = mutableListOf<String>()
+        
+        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.S) {
+            permissions.addAll(listOf(
+                Manifest.permission.BLUETOOTH_ADVERTISE,
+                Manifest.permission.BLUETOOTH_CONNECT,
+                Manifest.permission.BLUETOOTH_SCAN
+            ))
+        } else {
+            permissions.addAll(listOf(
+                Manifest.permission.BLUETOOTH,
+                Manifest.permission.BLUETOOTH_ADMIN
+            ))
+        }
+        
+        permissions.addAll(listOf(
+            Manifest.permission.ACCESS_COARSE_LOCATION,
+            Manifest.permission.ACCESS_FINE_LOCATION
+        ))
+        
+        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.TIRAMISU) {
+            permissions.add(Manifest.permission.POST_NOTIFICATIONS)
+        }
+        
+        permissionLauncher.launch(permissions.toTypedArray())
+    }
+    
+    override fun onDestroy() {
+        super.onDestroy()
+        // FIXED: Ensure Bluetooth resources are cleaned up when the activity is destroyed
+        // This addresses the issue where stale Bluetooth advertisements interfere with 
+        // restart discovery times. This is more reliable than relying solely on 
+        // ChatViewModel.onCleared() which may not be called when the app is swiped away.
+        try {
+            chatViewModel.meshService.stopServices()
+        } catch (e: Exception) {
+            // Log error, but don't crash the app on exit
+            android.util.Log.w("MainActivity", "Error stopping mesh services in onDestroy: ${e.message}")
+        }
+    }
+}

app/src/main/java/com/bitchat/android/crypto/EncryptionService.kt

@@ -0,0 +1,321 @@
+package com.bitchat.android.crypto
+
+import android.content.Context
+import android.content.SharedPreferences
+import android.security.keystore.KeyGenParameterSpec
+import android.security.keystore.KeyProperties
+import org.bouncycastle.crypto.agreement.X25519Agreement
+import org.bouncycastle.crypto.generators.Ed25519KeyPairGenerator
+import org.bouncycastle.crypto.generators.X25519KeyPairGenerator
+import org.bouncycastle.crypto.params.*
+import org.bouncycastle.crypto.signers.Ed25519Signer
+import org.bouncycastle.crypto.util.PrivateKeyFactory
+import org.bouncycastle.crypto.util.PublicKeyFactory
+import org.bouncycastle.jcajce.provider.digest.SHA256
+import java.security.SecureRandom
+import javax.crypto.Cipher
+import javax.crypto.KeyGenerator
+import javax.crypto.spec.GCMParameterSpec
+import javax.crypto.spec.SecretKeySpec
+import kotlin.experimental.and
+
+/**
+ * Encryption service that's 100% compatible with iOS version
+ * Uses the same cryptographic algorithms and key derivation
+ */
+class EncryptionService(private val context: Context) {
+    
+    // Key agreement keys for encryption
+    private val privateKey: X25519PrivateKeyParameters
+    private val publicKey: X25519PublicKeyParameters
+    
+    // Signing keys for authentication
+    private val signingPrivateKey: Ed25519PrivateKeyParameters
+    private val signingPublicKey: Ed25519PublicKeyParameters
+    
+    // Persistent identity for favorites (separate from ephemeral keys)
+    private lateinit var identityKey: Ed25519PrivateKeyParameters
+    private lateinit var identityPublicKey: Ed25519PublicKeyParameters
+    
+    // Storage for peer keys
+    private val peerPublicKeys = mutableMapOf<String, X25519PublicKeyParameters>()
+    private val peerSigningKeys = mutableMapOf<String, Ed25519PublicKeyParameters>()
+    private val peerIdentityKeys = mutableMapOf<String, Ed25519PublicKeyParameters>()
+    private val sharedSecrets = mutableMapOf<String, ByteArray>()
+    
+    private val prefs: SharedPreferences = context.getSharedPreferences("bitchat_crypto", Context.MODE_PRIVATE)
+    private val secureRandom = SecureRandom()
+    
+    init {
+        // Generate ephemeral key pairs for this session
+        val x25519Generator = X25519KeyPairGenerator()
+        x25519Generator.init(X25519KeyGenerationParameters(secureRandom))
+        val x25519KeyPair = x25519Generator.generateKeyPair()
+        privateKey = x25519KeyPair.private as X25519PrivateKeyParameters
+        publicKey = x25519KeyPair.public as X25519PublicKeyParameters
+        
+        val ed25519Generator = Ed25519KeyPairGenerator()
+        ed25519Generator.init(Ed25519KeyGenerationParameters(secureRandom))
+        val ed25519KeyPair = ed25519Generator.generateKeyPair()
+        signingPrivateKey = ed25519KeyPair.private as Ed25519PrivateKeyParameters
+        signingPublicKey = ed25519KeyPair.public as Ed25519PublicKeyParameters
+        
+        // Load or create persistent identity key
+        val identityKeyBytes = prefs.getString("identity_key", null)
+        if (identityKeyBytes != null) {
+            try {
+                val keyBytes = android.util.Base64.decode(identityKeyBytes, android.util.Base64.DEFAULT)
+                identityKey = Ed25519PrivateKeyParameters(keyBytes, 0)
+            } catch (e: Exception) {
+                // Create new identity key if loading fails
+                val newIdentityKeyPair = ed25519Generator.generateKeyPair()
+                identityKey = newIdentityKeyPair.private as Ed25519PrivateKeyParameters
+                saveIdentityKey()
+            }
+        } else {
+            // First run - create and save identity key
+            val newIdentityKeyPair = ed25519Generator.generateKeyPair()
+            identityKey = newIdentityKeyPair.private as Ed25519PrivateKeyParameters
+            saveIdentityKey()
+        }
+        identityPublicKey = Ed25519PublicKeyParameters(identityKey.encoded, 0)
+    }
+    
+    private fun saveIdentityKey() {
+        val keyBytes = android.util.Base64.encodeToString(identityKey.encoded, android.util.Base64.DEFAULT)
+        prefs.edit().putString("identity_key", keyBytes).apply()
+    }
+    
+    /**
+     * Create combined public key data for exchange - exactly same format as iOS
+     * 96 bytes total: 32 (X25519) + 32 (Ed25519 signing) + 32 (Ed25519 identity)
+     */
+    fun getCombinedPublicKeyData(): ByteArray {
+        val combined = ByteArray(96)
+        System.arraycopy(publicKey.encoded, 0, combined, 0, 32)  // X25519 key
+        System.arraycopy(signingPublicKey.encoded, 0, combined, 32, 32)  // Ed25519 signing key
+        System.arraycopy(identityPublicKey.encoded, 0, combined, 64, 32)  // Ed25519 identity key
+        return combined
+    }
+    
+    /**
+     * Add peer's combined public keys - exactly same logic as iOS
+     */
+    @Throws(Exception::class)
+    fun addPeerPublicKey(peerID: String, publicKeyData: ByteArray) {
+        if (publicKeyData.size != 96) {
+            throw Exception("Invalid public key data size: ${publicKeyData.size}, expected 96")
+        }
+        
+        // Extract all three keys: 32 for key agreement + 32 for signing + 32 for identity
+        val keyAgreementData = publicKeyData.sliceArray(0..31)
+        val signingKeyData = publicKeyData.sliceArray(32..63)
+        val identityKeyData = publicKeyData.sliceArray(64..95)
+        
+        val peerPublicKey = X25519PublicKeyParameters(keyAgreementData, 0)
+        peerPublicKeys[peerID] = peerPublicKey
+        
+        val peerSigningKey = Ed25519PublicKeyParameters(signingKeyData, 0)
+        peerSigningKeys[peerID] = peerSigningKey
+        
+        val peerIdentityKey = Ed25519PublicKeyParameters(identityKeyData, 0)
+        peerIdentityKeys[peerID] = peerIdentityKey
+        
+        // Generate shared secret for encryption using X25519
+        val agreement = X25519Agreement()
+        agreement.init(privateKey)
+        val sharedSecret = ByteArray(32)
+        agreement.calculateAgreement(peerPublicKey, sharedSecret, 0)
+        
+        // Derive symmetric key using HKDF with same salt as iOS
+        val salt = "bitchat-v1".toByteArray()
+        val derivedKey = hkdf(sharedSecret, salt, byteArrayOf(), 32)
+        sharedSecrets[peerID] = derivedKey
+    }
+    
+    /**
+     * Get peer's persistent identity key for favorites
+     */
+    fun getPeerIdentityKey(peerID: String): ByteArray? {
+        return peerIdentityKeys[peerID]?.encoded
+    }
+    
+    /**
+     * Clear persistent identity (for panic mode)
+     */
+    fun clearPersistentIdentity() {
+        prefs.edit().remove("identity_key").apply()
+    }
+    
+    /**
+     * Encrypt data for a specific peer using AES-256-GCM
+     */
+    @Throws(Exception::class)
+    fun encrypt(data: ByteArray, peerID: String): ByteArray {
+        val symmetricKey = sharedSecrets[peerID] 
+            ?: throw Exception("No shared secret for peer $peerID")
+        
+        val cipher = Cipher.getInstance("AES/GCM/NoPadding")
+        val keySpec = SecretKeySpec(symmetricKey, "AES")
+        cipher.init(Cipher.ENCRYPT_MODE, keySpec)
+        
+        val iv = cipher.iv
+        val ciphertext = cipher.doFinal(data)
+        
+        // Combine IV and ciphertext (same format as iOS AES.GCM.SealedBox.combined)
+        val combined = ByteArray(iv.size + ciphertext.size)
+        System.arraycopy(iv, 0, combined, 0, iv.size)
+        System.arraycopy(ciphertext, 0, combined, iv.size, ciphertext.size)
+        
+        return combined
+    }
+    
+    /**
+     * Decrypt data from a specific peer
+     */
+    @Throws(Exception::class)
+    fun decrypt(data: ByteArray, peerID: String): ByteArray {
+        val symmetricKey = sharedSecrets[peerID] 
+            ?: throw Exception("No shared secret for peer $peerID")
+        
+        if (data.size < 16) { // 12 bytes IV + 16 bytes tag minimum for GCM
+            throw Exception("Invalid encrypted data size")
+        }
+        
+        val cipher = Cipher.getInstance("AES/GCM/NoPadding")
+        val keySpec = SecretKeySpec(symmetricKey, "AES")
+        
+        // Extract IV and ciphertext
+        val iv = data.sliceArray(0..11)  // GCM IV is 12 bytes
+        val ciphertext = data.sliceArray(12 until data.size)
+        
+        val gcmSpec = GCMParameterSpec(128, iv)  // 128-bit authentication tag
+        cipher.init(Cipher.DECRYPT_MODE, keySpec, gcmSpec)
+        
+        return cipher.doFinal(ciphertext)
+    }
+    
+    /**
+     * Sign data using Ed25519
+     */
+    @Throws(Exception::class)
+    fun sign(data: ByteArray): ByteArray {
+        val signer = Ed25519Signer()
+        signer.init(true, signingPrivateKey)
+        signer.update(data, 0, data.size)
+        return signer.generateSignature()
+    }
+    
+    /**
+     * Verify signature using Ed25519
+     */
+    @Throws(Exception::class)
+    fun verify(signature: ByteArray, data: ByteArray, peerID: String): Boolean {
+        val verifyingKey = peerSigningKeys[peerID] 
+            ?: throw Exception("No signing key for peer $peerID")
+        
+        val signer = Ed25519Signer()
+        signer.init(false, verifyingKey)
+        signer.update(data, 0, data.size)
+        return signer.verifySignature(signature)
+    }
+    
+    /**
+     * HKDF implementation using SHA256 - same as iOS HKDF
+     */
+    private fun hkdf(ikm: ByteArray, salt: ByteArray, info: ByteArray, length: Int): ByteArray {
+        // Extract
+        val hmac = javax.crypto.Mac.getInstance("HmacSHA256")
+        val saltKey = SecretKeySpec(if (salt.isEmpty()) ByteArray(32) else salt, "HmacSHA256")
+        hmac.init(saltKey)
+        val prk = hmac.doFinal(ikm)
+        
+        // Expand
+        hmac.init(SecretKeySpec(prk, "HmacSHA256"))
+        val result = ByteArray(length)
+        var offset = 0
+        var counter = 1
+        
+        while (offset < length) {
+            hmac.reset()
+            if (counter > 1) {
+                hmac.update(result, offset - 32, 32)
+            }
+            hmac.update(info)
+            hmac.update(counter.toByte())
+            
+            val t = hmac.doFinal()
+            val remaining = length - offset
+            val toCopy = minOf(t.size, remaining)
+            System.arraycopy(t, 0, result, offset, toCopy)
+            
+            offset += toCopy
+            counter++
+        }
+        
+        return result
+    }
+}
+
+/**
+ * Message padding utilities - exact same as iOS version
+ */
+object MessagePadding {
+    // Standard block sizes for padding
+    private val blockSizes = listOf(256, 512, 1024, 2048)
+    
+    /**
+     * Add PKCS#7-style padding to reach target size
+     */
+    fun pad(data: ByteArray, targetSize: Int): ByteArray {
+        if (data.size >= targetSize) return data
+        
+        val paddingNeeded = targetSize - data.size
+        
+        // PKCS#7 only supports padding up to 255 bytes
+        if (paddingNeeded > 255) return data
+        
+        val padded = ByteArray(targetSize)
+        System.arraycopy(data, 0, padded, 0, data.size)
+        
+        // Fill with random bytes except the last byte
+        val random = SecureRandom()
+        random.nextBytes(padded.sliceArray(data.size until targetSize - 1))
+        
+        // Last byte indicates padding length (PKCS#7)
+        padded[targetSize - 1] = paddingNeeded.toByte()
+        
+        return padded
+    }
+    
+    /**
+     * Remove padding from data
+     */
+    fun unpad(data: ByteArray): ByteArray {
+        if (data.isEmpty()) return data
+        
+        // Last byte tells us how much padding to remove
+        val paddingLength = (data.last() and 0xFF.toByte()).toInt()
+        if (paddingLength <= 0 || paddingLength > data.size) return data
+        
+        return data.sliceArray(0 until (data.size - paddingLength))
+    }
+    
+    /**
+     * Find optimal block size for data
+     */
+    fun optimalBlockSize(dataSize: Int): Int {
+        // Account for encryption overhead (~16 bytes for AES-GCM tag)
+        val totalSize = dataSize + 16
+        
+        // Find smallest block that fits
+        for (blockSize in blockSizes) {
+            if (totalSize <= blockSize) {
+                return blockSize
+            }
+        }
+        
+        // For very large messages, just use the original size
+        return dataSize
+    }
+}

app/src/main/java/com/bitchat/android/model/BitchatMessage.kt

@@ -0,0 +1,407 @@
+package com.bitchat.android.model
+
+import android.os.Parcelable
+import kotlinx.parcelize.Parcelize
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+import java.util.*
+
+/**
+ * Delivery status for messages - exact same as iOS version
+ */
+sealed class DeliveryStatus : Parcelable {
+    @Parcelize
+    object Sending : DeliveryStatus()
+    
+    @Parcelize
+    object Sent : DeliveryStatus()
+    
+    @Parcelize
+    data class Delivered(val to: String, val at: Date) : DeliveryStatus()
+    
+    @Parcelize
+    data class Read(val by: String, val at: Date) : DeliveryStatus()
+    
+    @Parcelize
+    data class Failed(val reason: String) : DeliveryStatus()
+    
+    @Parcelize
+    data class PartiallyDelivered(val reached: Int, val total: Int) : DeliveryStatus()
+    
+    fun getDisplayText(): String {
+        return when (this) {
+            is Sending -> "Sending..."
+            is Sent -> "Sent"
+            is Delivered -> "Delivered to ${this.to}"
+            is Read -> "Read by ${this.by}"
+            is Failed -> "Failed: ${this.reason}"
+            is PartiallyDelivered -> "Delivered to ${this.reached}/${this.total}"
+        }
+    }
+}
+
+/**
+ * BitchatMessage - 100% compatible with iOS version
+ */
+@Parcelize
+data class BitchatMessage(
+    val id: String = UUID.randomUUID().toString(),
+    val sender: String,
+    val content: String,
+    val timestamp: Date,
+    val isRelay: Boolean = false,
+    val originalSender: String? = null,
+    val isPrivate: Boolean = false,
+    val recipientNickname: String? = null,
+    val senderPeerID: String? = null,
+    val mentions: List<String>? = null,
+    val channel: String? = null,
+    val encryptedContent: ByteArray? = null,
+    val isEncrypted: Boolean = false,
+    val deliveryStatus: DeliveryStatus? = null
+) : Parcelable {
+
+    /**
+     * Convert message to binary payload format - exactly same as iOS version
+     */
+    fun toBinaryPayload(): ByteArray? {
+        try {
+            val buffer = ByteBuffer.allocate(4096).apply { order(ByteOrder.BIG_ENDIAN) }
+            
+            // Message format:
+            // - Flags: 1 byte (bit flags for optional fields)
+            // - Timestamp: 8 bytes (milliseconds since epoch, big-endian)
+            // - ID length: 1 byte + ID data
+            // - Sender length: 1 byte + sender data
+            // - Content length: 2 bytes + content data (or encrypted content)
+            // Optional fields based on flags...
+            
+            var flags: UByte = 0u
+            if (isRelay) flags = flags or 0x01u
+            if (isPrivate) flags = flags or 0x02u
+            if (originalSender != null) flags = flags or 0x04u
+            if (recipientNickname != null) flags = flags or 0x08u
+            if (senderPeerID != null) flags = flags or 0x10u
+            if (mentions != null && mentions.isNotEmpty()) flags = flags or 0x20u
+            if (channel != null) flags = flags or 0x40u
+            if (isEncrypted) flags = flags or 0x80u
+            
+            buffer.put(flags.toByte())
+            
+            // Timestamp (in milliseconds, 8 bytes big-endian)
+            val timestampMillis = timestamp.time
+            buffer.putLong(timestampMillis)
+            
+            // ID
+            val idBytes = id.toByteArray(Charsets.UTF_8)
+            buffer.put(minOf(idBytes.size, 255).toByte())
+            buffer.put(idBytes.take(255).toByteArray())
+            
+            // Sender
+            val senderBytes = sender.toByteArray(Charsets.UTF_8)
+            buffer.put(minOf(senderBytes.size, 255).toByte())
+            buffer.put(senderBytes.take(255).toByteArray())
+            
+            // Content or encrypted content
+            if (isEncrypted && encryptedContent != null) {
+                val length = minOf(encryptedContent.size, 65535)
+                buffer.putShort(length.toShort())
+                buffer.put(encryptedContent.take(length).toByteArray())
+            } else {
+                val contentBytes = content.toByteArray(Charsets.UTF_8)
+                val length = minOf(contentBytes.size, 65535)
+                buffer.putShort(length.toShort())
+                buffer.put(contentBytes.take(length).toByteArray())
+            }
+            
+            // Optional fields
+            originalSender?.let { origSender ->
+                val origBytes = origSender.toByteArray(Charsets.UTF_8)
+                buffer.put(minOf(origBytes.size, 255).toByte())
+                buffer.put(origBytes.take(255).toByteArray())
+            }
+            
+            recipientNickname?.let { recipient ->
+                val recipBytes = recipient.toByteArray(Charsets.UTF_8)
+                buffer.put(minOf(recipBytes.size, 255).toByte())
+                buffer.put(recipBytes.take(255).toByteArray())
+            }
+            
+            senderPeerID?.let { peerID ->
+                val peerBytes = peerID.toByteArray(Charsets.UTF_8)
+                buffer.put(minOf(peerBytes.size, 255).toByte())
+                buffer.put(peerBytes.take(255).toByteArray())
+            }
+            
+            // Mentions array
+            mentions?.let { mentionList ->
+                buffer.put(minOf(mentionList.size, 255).toByte())
+                mentionList.take(255).forEach { mention ->
+                    val mentionBytes = mention.toByteArray(Charsets.UTF_8)
+                    buffer.put(minOf(mentionBytes.size, 255).toByte())
+                    buffer.put(mentionBytes.take(255).toByteArray())
+                }
+            }
+            
+            // Channel hashtag
+            channel?.let { channelName ->
+                val channelBytes = channelName.toByteArray(Charsets.UTF_8)
+                buffer.put(minOf(channelBytes.size, 255).toByte())
+                buffer.put(channelBytes.take(255).toByteArray())
+            }
+            
+            val result = ByteArray(buffer.position())
+            buffer.rewind()
+            buffer.get(result)
+            return result
+            
+        } catch (e: Exception) {
+            return null
+        }
+    }
+    
+    companion object {
+        /**
+         * Parse message from binary payload - exactly same logic as iOS version
+         */
+        fun fromBinaryPayload(data: ByteArray): BitchatMessage? {
+            try {
+                if (data.size < 13) return null
+                
+                val buffer = ByteBuffer.wrap(data).apply { order(ByteOrder.BIG_ENDIAN) }
+                
+                // Flags
+                val flags = buffer.get().toUByte()
+                val isRelay = (flags and 0x01u) != 0u.toUByte()
+                val isPrivate = (flags and 0x02u) != 0u.toUByte()
+                val hasOriginalSender = (flags and 0x04u) != 0u.toUByte()
+                val hasRecipientNickname = (flags and 0x08u) != 0u.toUByte()
+                val hasSenderPeerID = (flags and 0x10u) != 0u.toUByte()
+                val hasMentions = (flags and 0x20u) != 0u.toUByte()
+                val hasChannel = (flags and 0x40u) != 0u.toUByte()
+                val isEncrypted = (flags and 0x80u) != 0u.toUByte()
+                
+                // Timestamp
+                val timestampMillis = buffer.getLong()
+                val timestamp = Date(timestampMillis)
+                
+                // ID
+                val idLength = buffer.get().toInt() and 0xFF
+                if (buffer.remaining() < idLength) return null
+                val idBytes = ByteArray(idLength)
+                buffer.get(idBytes)
+                val id = String(idBytes, Charsets.UTF_8)
+                
+                // Sender
+                val senderLength = buffer.get().toInt() and 0xFF
+                if (buffer.remaining() < senderLength) return null
+                val senderBytes = ByteArray(senderLength)
+                buffer.get(senderBytes)
+                val sender = String(senderBytes, Charsets.UTF_8)
+                
+                // Content
+                val contentLength = buffer.getShort().toInt() and 0xFFFF
+                if (buffer.remaining() < contentLength) return null
+                
+                val content: String
+                val encryptedContent: ByteArray?
+                
+                if (isEncrypted) {
+                    val encryptedBytes = ByteArray(contentLength)
+                    buffer.get(encryptedBytes)
+                    encryptedContent = encryptedBytes
+                    content = "" // Empty placeholder
+                } else {
+                    val contentBytes = ByteArray(contentLength)
+                    buffer.get(contentBytes)
+                    content = String(contentBytes, Charsets.UTF_8)
+                    encryptedContent = null
+                }
+                
+                // Optional fields
+                val originalSender = if (hasOriginalSender && buffer.hasRemaining()) {
+                    val length = buffer.get().toInt() and 0xFF
+                    if (buffer.remaining() >= length) {
+                        val bytes = ByteArray(length)
+                        buffer.get(bytes)
+                        String(bytes, Charsets.UTF_8)
+                    } else null
+                } else null
+                
+                val recipientNickname = if (hasRecipientNickname && buffer.hasRemaining()) {
+                    val length = buffer.get().toInt() and 0xFF
+                    if (buffer.remaining() >= length) {
+                        val bytes = ByteArray(length)
+                        buffer.get(bytes)
+                        String(bytes, Charsets.UTF_8)
+                    } else null
+                } else null
+                
+                val senderPeerID = if (hasSenderPeerID && buffer.hasRemaining()) {
+                    val length = buffer.get().toInt() and 0xFF
+                    if (buffer.remaining() >= length) {
+                        val bytes = ByteArray(length)
+                        buffer.get(bytes)
+                        String(bytes, Charsets.UTF_8)
+                    } else null
+                } else null
+                
+                // Mentions array
+                val mentions = if (hasMentions && buffer.hasRemaining()) {
+                    val mentionCount = buffer.get().toInt() and 0xFF
+                    val mentionList = mutableListOf<String>()
+                    repeat(mentionCount) {
+                        if (buffer.hasRemaining()) {
+                            val length = buffer.get().toInt() and 0xFF
+                            if (buffer.remaining() >= length) {
+                                val bytes = ByteArray(length)
+                                buffer.get(bytes)
+                                mentionList.add(String(bytes, Charsets.UTF_8))
+                            }
+                        }
+                    }
+                    if (mentionList.isNotEmpty()) mentionList else null
+                } else null
+                
+                // Channel
+                val channel = if (hasChannel && buffer.hasRemaining()) {
+                    val length = buffer.get().toInt() and 0xFF
+                    if (buffer.remaining() >= length) {
+                        val bytes = ByteArray(length)
+                        buffer.get(bytes)
+                        String(bytes, Charsets.UTF_8)
+                    } else null
+                } else null
+                
+                return BitchatMessage(
+                    id = id,
+                    sender = sender,
+                    content = content,
+                    timestamp = timestamp,
+                    isRelay = isRelay,
+                    originalSender = originalSender,
+                    isPrivate = isPrivate,
+                    recipientNickname = recipientNickname,
+                    senderPeerID = senderPeerID,
+                    mentions = mentions,
+                    channel = channel,
+                    encryptedContent = encryptedContent,
+                    isEncrypted = isEncrypted
+                )
+                
+            } catch (e: Exception) {
+                return null
+            }
+        }
+    }
+    
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (javaClass != other?.javaClass) return false
+        
+        other as BitchatMessage
+        
+        if (id != other.id) return false
+        if (sender != other.sender) return false
+        if (content != other.content) return false
+        if (timestamp != other.timestamp) return false
+        if (isRelay != other.isRelay) return false
+        if (originalSender != other.originalSender) return false
+        if (isPrivate != other.isPrivate) return false
+        if (recipientNickname != other.recipientNickname) return false
+        if (senderPeerID != other.senderPeerID) return false
+        if (mentions != other.mentions) return false
+        if (channel != other.channel) return false
+        if (encryptedContent != null) {
+            if (other.encryptedContent == null) return false
+            if (!encryptedContent.contentEquals(other.encryptedContent)) return false
+        } else if (other.encryptedContent != null) return false
+        if (isEncrypted != other.isEncrypted) return false
+        if (deliveryStatus != other.deliveryStatus) return false
+        
+        return true
+    }
+    
+    override fun hashCode(): Int {
+        var result = id.hashCode()
+        result = 31 * result + sender.hashCode()
+        result = 31 * result + content.hashCode()
+        result = 31 * result + timestamp.hashCode()
+        result = 31 * result + isRelay.hashCode()
+        result = 31 * result + (originalSender?.hashCode() ?: 0)
+        result = 31 * result + isPrivate.hashCode()
+        result = 31 * result + (recipientNickname?.hashCode() ?: 0)
+        result = 31 * result + (senderPeerID?.hashCode() ?: 0)
+        result = 31 * result + (mentions?.hashCode() ?: 0)
+        result = 31 * result + (channel?.hashCode() ?: 0)
+        result = 31 * result + (encryptedContent?.contentHashCode() ?: 0)
+        result = 31 * result + isEncrypted.hashCode()
+        result = 31 * result + (deliveryStatus?.hashCode() ?: 0)
+        return result
+    }
+}
+
+/**
+ * Delivery acknowledgment structure - exact same as iOS version
+ */
+@Parcelize
+data class DeliveryAck(
+    val originalMessageID: String,
+    val ackID: String = UUID.randomUUID().toString(),
+    val recipientID: String,
+    val recipientNickname: String,
+    val timestamp: Date = Date(),
+    val hopCount: UByte
+) : Parcelable {
+    
+    fun encode(): ByteArray? {
+        return try {
+            com.google.gson.Gson().toJson(this).toByteArray(Charsets.UTF_8)
+        } catch (e: Exception) {
+            null
+        }
+    }
+    
+    companion object {
+        fun decode(data: ByteArray): DeliveryAck? {
+            return try {
+                val json = String(data, Charsets.UTF_8)
+                com.google.gson.Gson().fromJson(json, DeliveryAck::class.java)
+            } catch (e: Exception) {
+                null
+            }
+        }
+    }
+}
+
+/**
+ * Read receipt structure - exact same as iOS version
+ */
+@Parcelize
+data class ReadReceipt(
+    val originalMessageID: String,
+    val receiptID: String = UUID.randomUUID().toString(),
+    val readerID: String,
+    val readerNickname: String,
+    val timestamp: Date = Date()
+) : Parcelable {
+    
+    fun encode(): ByteArray? {
+        return try {
+            com.google.gson.Gson().toJson(this).toByteArray(Charsets.UTF_8)
+        } catch (e: Exception) {
+            null
+        }
+    }
+    
+    companion object {
+        fun decode(data: ByteArray): ReadReceipt? {
+            return try {
+                val json = String(data, Charsets.UTF_8)
+                com.google.gson.Gson().fromJson(json, ReadReceipt::class.java)
+            } catch (e: Exception) {
+                null
+            }
+        }
+    }
+}

app/src/main/java/com/bitchat/android/protocol/BinaryProtocol.kt

@@ -0,0 +1,334 @@
+package com.bitchat.android.protocol
+
+import android.os.Parcelable
+import kotlinx.parcelize.Parcelize
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+import java.util.*
+
+/**
+ * Message types - exact same as iOS version
+ */
+enum class MessageType(val value: UByte) {
+    ANNOUNCE(0x01u),
+    KEY_EXCHANGE(0x02u),
+    LEAVE(0x03u),
+    MESSAGE(0x04u),
+    FRAGMENT_START(0x05u),
+    FRAGMENT_CONTINUE(0x06u),
+    FRAGMENT_END(0x07u),
+    CHANNEL_ANNOUNCE(0x08u),
+    CHANNEL_RETENTION(0x09u),
+    DELIVERY_ACK(0x0Au),
+    DELIVERY_STATUS_REQUEST(0x0Bu),
+    READ_RECEIPT(0x0Cu);
+
+    companion object {
+        fun fromValue(value: UByte): MessageType? {
+            return values().find { it.value == value }
+        }
+    }
+}
+
+/**
+ * Special recipient IDs - exact same as iOS version
+ */
+object SpecialRecipients {
+    val BROADCAST = ByteArray(8) { 0xFF.toByte() }  // All 0xFF = broadcast
+}
+
+/**
+ * Binary packet format - 100% compatible with iOS version
+ * 
+ * Header (Fixed 13 bytes):
+ * - Version: 1 byte
+ * - Type: 1 byte  
+ * - TTL: 1 byte
+ * - Timestamp: 8 bytes (UInt64, big-endian)
+ * - Flags: 1 byte (bit 0: hasRecipient, bit 1: hasSignature, bit 2: isCompressed)
+ * - PayloadLength: 2 bytes (UInt16, big-endian)
+ *
+ * Variable sections:
+ * - SenderID: 8 bytes (fixed)
+ * - RecipientID: 8 bytes (if hasRecipient flag set)
+ * - Payload: Variable length (includes original size if compressed)
+ * - Signature: 64 bytes (if hasSignature flag set)
+ */
+@Parcelize
+data class BitchatPacket(
+    val version: UByte = 1u,
+    val type: UByte,
+    val senderID: ByteArray,
+    val recipientID: ByteArray? = null,
+    val timestamp: ULong,
+    val payload: ByteArray,
+    val signature: ByteArray? = null,
+    var ttl: UByte
+) : Parcelable {
+
+    constructor(
+        type: UByte,
+        ttl: UByte,
+        senderID: String,
+        payload: ByteArray
+    ) : this(
+        version = 1u,
+        type = type,
+        senderID = senderID.toByteArray(),
+        recipientID = null,
+        timestamp = (System.currentTimeMillis()).toULong(),
+        payload = payload,
+        signature = null,
+        ttl = ttl
+    )
+
+    fun toBinaryData(): ByteArray? {
+        return BinaryProtocol.encode(this)
+    }
+
+    companion object {
+        fun fromBinaryData(data: ByteArray): BitchatPacket? {
+            return BinaryProtocol.decode(data)
+        }
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (javaClass != other?.javaClass) return false
+
+        other as BitchatPacket
+
+        if (version != other.version) return false
+        if (type != other.type) return false
+        if (!senderID.contentEquals(other.senderID)) return false
+        if (recipientID != null) {
+            if (other.recipientID == null) return false
+            if (!recipientID.contentEquals(other.recipientID)) return false
+        } else if (other.recipientID != null) return false
+        if (timestamp != other.timestamp) return false
+        if (!payload.contentEquals(other.payload)) return false
+        if (signature != null) {
+            if (other.signature == null) return false
+            if (!signature.contentEquals(other.signature)) return false
+        } else if (other.signature != null) return false
+        if (ttl != other.ttl) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int {
+        var result = version.hashCode()
+        result = 31 * result + type.hashCode()
+        result = 31 * result + senderID.contentHashCode()
+        result = 31 * result + (recipientID?.contentHashCode() ?: 0)
+        result = 31 * result + timestamp.hashCode()
+        result = 31 * result + payload.contentHashCode()
+        result = 31 * result + (signature?.contentHashCode() ?: 0)
+        result = 31 * result + ttl.hashCode()
+        return result
+    }
+}
+
+/**
+ * Binary Protocol implementation - exact same format as iOS version
+ */
+object BinaryProtocol {
+    private const val HEADER_SIZE = 13
+    private const val SENDER_ID_SIZE = 8
+    private const val RECIPIENT_ID_SIZE = 8
+    private const val SIGNATURE_SIZE = 64
+    
+    object Flags {
+        const val HAS_RECIPIENT: UByte = 0x01u
+        const val HAS_SIGNATURE: UByte = 0x02u
+        const val IS_COMPRESSED: UByte = 0x04u
+    }
+    
+    fun encode(packet: BitchatPacket): ByteArray? {
+        try {
+            // Try to compress payload if beneficial
+            var payload = packet.payload
+            var originalPayloadSize: UShort? = null
+            var isCompressed = false
+            
+            if (CompressionUtil.shouldCompress(payload)) {
+                CompressionUtil.compress(payload)?.let { compressedPayload ->
+                    originalPayloadSize = payload.size.toUShort()
+                    payload = compressedPayload
+                    isCompressed = true
+                }
+            }
+            
+            val buffer = ByteBuffer.allocate(4096).apply { order(ByteOrder.BIG_ENDIAN) }
+            
+            // Header
+            buffer.put(packet.version.toByte())
+            buffer.put(packet.type.toByte())
+            buffer.put(packet.ttl.toByte())
+            
+            // Timestamp (8 bytes, big-endian)
+            buffer.putLong(packet.timestamp.toLong())
+            
+            // Flags
+            var flags: UByte = 0u
+            if (packet.recipientID != null) {
+                flags = flags or Flags.HAS_RECIPIENT
+            }
+            if (packet.signature != null) {
+                flags = flags or Flags.HAS_SIGNATURE
+            }
+            if (isCompressed) {
+                flags = flags or Flags.IS_COMPRESSED
+            }
+            buffer.put(flags.toByte())
+            
+            // Payload length (2 bytes, big-endian) - includes original size if compressed
+            val payloadDataSize = payload.size + if (isCompressed) 2 else 0
+            buffer.putShort(payloadDataSize.toShort())
+            
+            // SenderID (exactly 8 bytes)
+            val senderBytes = packet.senderID.take(SENDER_ID_SIZE).toByteArray()
+            buffer.put(senderBytes)
+            if (senderBytes.size < SENDER_ID_SIZE) {
+                buffer.put(ByteArray(SENDER_ID_SIZE - senderBytes.size))
+            }
+            
+            // RecipientID (if present)
+            packet.recipientID?.let { recipientID ->
+                val recipientBytes = recipientID.take(RECIPIENT_ID_SIZE).toByteArray()
+                buffer.put(recipientBytes)
+                if (recipientBytes.size < RECIPIENT_ID_SIZE) {
+                    buffer.put(ByteArray(RECIPIENT_ID_SIZE - recipientBytes.size))
+                }
+            }
+            
+            // Payload (with original size prepended if compressed)
+            if (isCompressed) {
+                val originalSize = originalPayloadSize
+                if (originalSize != null) {
+                    buffer.putShort(originalSize.toShort())
+                }
+            }
+            buffer.put(payload)
+            
+            // Signature (if present)
+            packet.signature?.let { signature ->
+                buffer.put(signature.take(SIGNATURE_SIZE).toByteArray())
+            }
+            
+            val result = ByteArray(buffer.position())
+            buffer.rewind()
+            buffer.get(result)
+            return result
+            
+        } catch (e: Exception) {
+            return null
+        }
+    }
+    
+    fun decode(data: ByteArray): BitchatPacket? {
+        try {
+            if (data.size < HEADER_SIZE + SENDER_ID_SIZE) return null
+            
+            val buffer = ByteBuffer.wrap(data).apply { order(ByteOrder.BIG_ENDIAN) }
+            
+            // Header
+            val version = buffer.get().toUByte()
+            if (version != 1u.toUByte()) return null
+            
+            val type = buffer.get().toUByte()
+            val ttl = buffer.get().toUByte()
+            
+            // Timestamp
+            val timestamp = buffer.getLong().toULong()
+            
+            // Flags
+            val flags = buffer.get().toUByte()
+            val hasRecipient = (flags and Flags.HAS_RECIPIENT) != 0u.toUByte()
+            val hasSignature = (flags and Flags.HAS_SIGNATURE) != 0u.toUByte()
+            val isCompressed = (flags and Flags.IS_COMPRESSED) != 0u.toUByte()
+            
+            // Payload length
+            val payloadLength = buffer.getShort().toUShort()
+            
+            // Calculate expected total size
+            var expectedSize = HEADER_SIZE + SENDER_ID_SIZE + payloadLength.toInt()
+            if (hasRecipient) expectedSize += RECIPIENT_ID_SIZE
+            if (hasSignature) expectedSize += SIGNATURE_SIZE
+            
+            if (data.size < expectedSize) return null
+            
+            // SenderID
+            val senderID = ByteArray(SENDER_ID_SIZE)
+            buffer.get(senderID)
+            
+            // RecipientID
+            val recipientID = if (hasRecipient) {
+                val recipientBytes = ByteArray(RECIPIENT_ID_SIZE)
+                buffer.get(recipientBytes)
+                recipientBytes
+            } else null
+            
+            // Payload
+            val payload = if (isCompressed) {
+                // First 2 bytes are original size
+                if (payloadLength.toInt() < 2) return null
+                val originalSize = buffer.getShort().toInt()
+                
+                // Compressed payload
+                val compressedPayload = ByteArray(payloadLength.toInt() - 2)
+                buffer.get(compressedPayload)
+                
+                // Decompress
+                CompressionUtil.decompress(compressedPayload, originalSize) ?: return null
+            } else {
+                val payloadBytes = ByteArray(payloadLength.toInt())
+                buffer.get(payloadBytes)
+                payloadBytes
+            }
+            
+            // Signature
+            val signature = if (hasSignature) {
+                val signatureBytes = ByteArray(SIGNATURE_SIZE)
+                buffer.get(signatureBytes)
+                signatureBytes
+            } else null
+            
+            return BitchatPacket(
+                version = version,
+                type = type,
+                senderID = senderID,
+                recipientID = recipientID,
+                timestamp = timestamp,
+                payload = payload,
+                signature = signature,
+                ttl = ttl
+            )
+            
+        } catch (e: Exception) {
+            return null
+        }
+    }
+}
+
+/**
+ * Compression utilities - temporarily disabled for initial build
+ */
+object CompressionUtil {
+    private const val COMPRESSION_THRESHOLD = 100  // bytes
+    
+    fun shouldCompress(data: ByteArray): Boolean {
+        // Temporarily disabled compression
+        return false
+    }
+    
+    fun compress(data: ByteArray): ByteArray? {
+        // Temporarily disabled compression
+        return null
+    }
+    
+    fun decompress(compressedData: ByteArray, originalSize: Int): ByteArray? {
+        // Temporarily disabled compression
+        return null
+    }
+}

app/src/main/java/com/bitchat/android/ui/theme/Theme.kt

@@ -0,0 +1,52 @@
+package com.bitchat.android.ui.theme
+
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.darkColorScheme
+import androidx.compose.material3.lightColorScheme
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.graphics.Color
+
+// Colors that match the iOS bitchat theme
+private val DarkColorScheme = darkColorScheme(
+    primary = Color(0xFF00FF00),        // Bright green (terminal-like)
+    onPrimary = Color.Black,
+    secondary = Color(0xFF00CC00),      // Darker green
+    onSecondary = Color.Black,
+    background = Color.Black,
+    onBackground = Color(0xFF00FF00),   // Green on black
+    surface = Color(0xFF111111),        // Very dark gray
+    onSurface = Color(0xFF00FF00),      // Green text
+    error = Color(0xFFFF5555),          // Red for errors
+    onError = Color.Black
+)
+
+private val LightColorScheme = lightColorScheme(
+    primary = Color(0xFF008000),        // Dark green
+    onPrimary = Color.White,
+    secondary = Color(0xFF006600),      // Even darker green
+    onSecondary = Color.White,
+    background = Color.White,
+    onBackground = Color(0xFF008000),   // Dark green on white
+    surface = Color(0xFFF8F8F8),        // Very light gray
+    onSurface = Color(0xFF008000),      // Dark green text
+    error = Color(0xFFCC0000),          // Dark red for errors
+    onError = Color.White
+)
+
+@Composable
+fun BitchatTheme(
+    darkTheme: Boolean = isSystemInDarkTheme(),
+    content: @Composable () -> Unit
+) {
+    val colorScheme = when {
+        darkTheme -> DarkColorScheme
+        else -> LightColorScheme
+    }
+
+    MaterialTheme(
+        colorScheme = colorScheme,
+        typography = Typography,
+        content = content
+    )
+}

app/src/main/java/com/bitchat/android/ui/theme/Typography.kt

@@ -0,0 +1,53 @@
+package com.bitchat.android.ui.theme
+
+import androidx.compose.material3.Typography
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.sp
+
+// Typography matching the iOS monospace design - increased font sizes for better readability
+val Typography = Typography(
+    bodyLarge = TextStyle(
+        fontFamily = FontFamily.Monospace,
+        fontWeight = FontWeight.Normal,
+        fontSize = 16.sp,
+        lineHeight = 22.sp
+    ),
+    bodyMedium = TextStyle(
+        fontFamily = FontFamily.Monospace,
+        fontWeight = FontWeight.Normal,
+        fontSize = 14.sp,
+        lineHeight = 18.sp
+    ),
+    bodySmall = TextStyle(
+        fontFamily = FontFamily.Monospace,
+        fontWeight = FontWeight.Normal,
+        fontSize = 12.sp,
+        lineHeight = 16.sp
+    ),
+    headlineSmall = TextStyle(
+        fontFamily = FontFamily.Monospace,
+        fontWeight = FontWeight.Medium,
+        fontSize = 18.sp,
+        lineHeight = 24.sp
+    ),
+    titleMedium = TextStyle(
+        fontFamily = FontFamily.Monospace,
+        fontWeight = FontWeight.Medium,
+        fontSize = 16.sp,
+        lineHeight = 22.sp
+    ),
+    labelMedium = TextStyle(
+        fontFamily = FontFamily.Monospace,
+        fontWeight = FontWeight.Medium,
+        fontSize = 13.sp,
+        lineHeight = 18.sp
+    ),
+    labelSmall = TextStyle(
+        fontFamily = FontFamily.Monospace,
+        fontWeight = FontWeight.Normal,
+        fontSize = 11.sp,
+        lineHeight = 16.sp
+    )
+)