NIP-17/44: adopt NIP-44 v2 (XChaCha20-Poly1305, v2: base64url), switch rumor kind to 14, randomize BIP-340 aux; add XChaCha20Poly1305Compat and wire-up

bitchat.xcodeproj/project.pbxproj

@@ -140,6 +140,8 @@
 		F455F011B3B648ADA233F998 /* BinaryProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = A2136C3E22D02D4A8DBE7EAB /* BinaryProtocol.swift */; };
 		FB8819B4C84FAFEF5C36B216 /* KeychainManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 136696FC4436A02D98CE6A77 /* KeychainManager.swift */; };
 		FBC409E105493C491531B59A /* NostrProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2E5A9FF4AEA8A923317ED26A /* NostrProtocol.swift */; };
+		A1B2C3D44E5F60718293A4B5 /* XChaCha20Poly1305Compat.swift in Sources */ = {isa = PBXBuildFile; fileRef = A1B2C3D44E5F60718293A4B4 /* XChaCha20Poly1305Compat.swift */; };
+		A1B2C3D54E5F60718293A4B6 /* XChaCha20Poly1305Compat.swift in Sources */ = {isa = PBXBuildFile; fileRef = A1B2C3D44E5F60718293A4B4 /* XChaCha20Poly1305Compat.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -258,6 +260,7 @@
 		FDC18D910D6FF2E8B1B6C885 /* SecureIdentityStateManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SecureIdentityStateManager.swift; sourceTree = "<group>"; };
 		FE7CCF2BD78A3F3DAE6DA145 /* MockBLEService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MockBLEService.swift; sourceTree = "<group>"; };
 		FF7AF93D874001FBD94C8306 /* bitchat-macOS.entitlements */ = {isa = PBXFileReference; lastKnownFileType = text.plist.entitlements; path = "bitchat-macOS.entitlements"; sourceTree = "<group>"; };
+		A1B2C3D44E5F60718293A4B4 /* XChaCha20Poly1305Compat.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = XChaCha20Poly1305Compat.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -522,6 +525,7 @@
 		E78C7F4B6769C0A72F5DE544 /* Nostr */ = {
 			isa = PBXGroup;
 			children = (
+				A1B2C3D44E5F60718293A4B4 /* XChaCha20Poly1305Compat.swift */,
 				049BD39B2E51DBD9001A566B /* NostrEmbeddedBitChat.swift */,
 				5F8043995007F0D84438EDD9 /* NostrIdentity.swift */,
 				2E5A9FF4AEA8A923317ED26A /* NostrProtocol.swift */,
@@ -720,6 +724,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				A1B2C3D54E5F60718293A4B6 /* XChaCha20Poly1305Compat.swift in Sources */,
 				AD11E46940D742AEAF547EB2 /* AppInfoView.swift in Sources */,
 				9B51E9B63A3EA59B1A7874BD /* BinaryEncodingUtils.swift in Sources */,
 				049BD3B42E51F319001A566B /* NostrTransport.swift in Sources */,
@@ -774,6 +779,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				A1B2C3D44E5F60718293A4B5 /* XChaCha20Poly1305Compat.swift in Sources */,
 				ABAF130D88561F4A646F0430 /* AppInfoView.swift in Sources */,
 				AFB6AEFCABBE97441CB3102B /* BinaryEncodingUtils.swift in Sources */,
 				049BD3B22E51F319001A566B /* NostrTransport.swift in Sources */,

bitchat/Nostr/NostrProtocol.swift

@@ -1,6 +1,7 @@
 import Foundation
 import CryptoKit
 import P256K
+import Security
 
 // Note: This file depends on Data extension from BinaryEncodingUtils.swift
 // Make sure BinaryEncodingUtils.swift is included in the target
@@ -12,8 +13,9 @@ struct NostrProtocol {
     enum EventKind: Int {
         case metadata = 0
         case textNote = 1
+        case dm = 14 // NIP-17 DM rumor kind
         case seal = 13 // NIP-17 sealed event
-        case giftWrap = 1059 // NIP-17 gift wrap
+        case giftWrap = 1059 // NIP-59 gift wrap
         case ephemeralEvent = 20000
     }
     
@@ -30,7 +32,7 @@ struct NostrProtocol {
         let rumor = NostrEvent(
             pubkey: senderIdentity.publicKeyHex,
             createdAt: Date(),
-            kind: .textNote,
+            kind: .dm, // NIP-17: DM rumor kind 14
             tags: [],
             content: content
         )
@@ -227,7 +229,7 @@ struct NostrProtocol {
         return try NostrEvent(from: rumorDict)
     }
     
-    // MARK: - Encryption (NIP-44 style)
+    // MARK: - Encryption (NIP-44 v2)
     
     private static func encrypt(
         plaintext: String,
@@ -239,33 +241,31 @@ struct NostrProtocol {
             throw NostrError.invalidPublicKey
         }
         
-        // Encrypting message
+        // Encrypting message (NIP-44 v2: XChaCha20-Poly1305, versioned)
         
         // Derive shared secret
         let sharedSecret = try deriveSharedSecret(
             privateKey: senderKey,
             publicKey: recipientPubkeyData
         )
+        // Derive NIP-44 v2 symmetric key (HKDF-SHA256 with label in info)
+        let key = try deriveNIP44V2Key(from: sharedSecret)
         
-        // Derived shared secret
+        // 24-byte random nonce for XChaCha20-Poly1305
+        var nonce24 = Data(count: 24)
+        _ = nonce24.withUnsafeMutableBytes { ptr in
+            SecRandomCopyBytes(kSecRandomDefault, 24, ptr.baseAddress!)
+        }
         
-        // Generate nonce
+        let pt = Data(plaintext.utf8)
-        let nonce = AES.GCM.Nonce()
+        let sealed = try XChaCha20Poly1305Compat.seal(plaintext: pt, key: key, nonce24: nonce24)
         
-        // Encrypt
+        // v2: base64url(nonce24 || ciphertext || tag)
-        let sealed = try AES.GCM.seal(
+        var combined = Data()
-            plaintext.data(using: .utf8)!,
+        combined.append(nonce24)
-            using: SymmetricKey(data: sharedSecret),
+        combined.append(sealed.ciphertext)
-            nonce: nonce
+        combined.append(sealed.tag)
-        )
+        return "v2:" + base64URLEncode(combined)
-        
-        // Combine nonce + ciphertext + tag
-        var result = Data()
-        result.append(nonce.withUnsafeBytes { Data($0) })
-        result.append(sealed.ciphertext)
-        result.append(sealed.tag)
-        
-        return result.base64EncodedString()
     }
     
     private static func decrypt(
@@ -273,86 +273,33 @@ struct NostrProtocol {
         senderPubkey: String,
         recipientKey: P256K.Schnorr.PrivateKey
     ) throws -> String {
-        
+        // Expect NIP-44 v2 format
-        // Decrypting message
+        guard ciphertext.hasPrefix("v2:") else { throw NostrError.invalidCiphertext }
-        
+        let encoded = String(ciphertext.dropFirst(3))
-        guard let data = Data(base64Encoded: ciphertext),
+        guard let data = base64URLDecode(encoded),
+              data.count > (24 + 16),
               let senderPubkeyData = Data(hexString: senderPubkey) else {
-            SecureLogger.log("❌ Invalid ciphertext or sender pubkey format", 
-                            category: SecureLogger.session, level: .error)
             throw NostrError.invalidCiphertext
         }
-        
+
-        // Ciphertext data parsed
+        let nonce24 = data.prefix(24)
-        
+        let rest = data.dropFirst(24)
-        // Extract components
+        let tag = rest.suffix(16)
-        let nonceData = data.prefix(12)
+        let ct = rest.dropLast(16)
-        let ciphertextData = data.dropFirst(12).dropLast(16)
+
-        let tagData = data.suffix(16)
+        // Derive shared secret (try even then odd Y)
-        
-        // Components parsed
-        
-        // Derive shared secret - try with default Y coordinate first
         var sharedSecret: Data
-        var decrypted: Data? = nil
-        
         do {
-            sharedSecret = try deriveSharedSecret(
+            sharedSecret = try deriveSharedSecret(privateKey: recipientKey, publicKey: senderPubkeyData)
-                privateKey: recipientKey,
-                publicKey: senderPubkeyData
-            )
-            // Derived shared secret with first Y coordinate
-            
-            // Try to decrypt
-            let sealedBox = try AES.GCM.SealedBox(
-                nonce: AES.GCM.Nonce(data: nonceData),
-                ciphertext: ciphertextData,
-                tag: tagData
-            )
-            
-            do {
-                decrypted = try AES.GCM.open(
-                    sealedBox,
-                    using: SymmetricKey(data: sharedSecret)
-                )
-                // AES-GCM decryption successful
-            } catch {
-                // AES-GCM decryption failed, trying alternate
-                
-                // If the sender pubkey is x-only (32 bytes), try the other Y coordinate
-                if senderPubkeyData.count == 32 {
-                    // Trying alternate Y coordinate
-                    
-                    // Force deriveSharedSecret to use odd Y by manipulating the data
-                    var altPubkey = Data()
-                    altPubkey.append(0x03) // Force odd Y
-                    altPubkey.append(senderPubkeyData)
-                    
-                    sharedSecret = try deriveSharedSecretDirect(
-                        privateKey: recipientKey,
-                        publicKey: altPubkey
-                    )
-                    
-                    decrypted = try AES.GCM.open(
-                        sealedBox,
-                        using: SymmetricKey(data: sharedSecret)
-                    )
-                    // AES-GCM decryption successful with alternate Y
-                } else {
-                    throw error
-                }
-            }
         } catch {
-            SecureLogger.log("❌ Failed to derive shared secret or decrypt: \(error)", 
+            guard senderPubkeyData.count == 32 else { throw error }
-                            category: SecureLogger.session, level: .error)
+            var alt = Data([0x03])
-            throw error
+            alt.append(senderPubkeyData)
+            sharedSecret = try deriveSharedSecretDirect(privateKey: recipientKey, publicKey: alt)
         }
-        
+        let key = try deriveNIP44V2Key(from: sharedSecret)
-        guard let finalDecrypted = decrypted else {
+        let pt = try XChaCha20Poly1305Compat.open(ciphertext: Data(ct), tag: Data(tag), key: key, nonce24: Data(nonce24))
-            throw NostrError.encryptionFailed
+        return String(data: pt, encoding: .utf8) ?? ""
-        }
-        
-        return String(data: finalDecrypted, encoding: .utf8) ?? ""
     }
     
     private static func deriveSharedSecret(
@@ -412,17 +359,8 @@ struct NostrProtocol {
         let sharedSecretData = sharedSecret.withUnsafeBytes { Data($0) }
         // ECDH shared secret derived
         
-        // Derive key using HKDF for NIP-44 v2
+        // Return raw ECDH shared secret; HKDF is applied by deriveNIP44V2Key
-        let derivedKey = HKDF<CryptoKit.SHA256>.deriveKey(
+        return sharedSecretData
-            inputKeyMaterial: SymmetricKey(data: sharedSecretData),
-            salt: "nip44-v2".data(using: .utf8)!,
-            info: Data(),
-            outputByteCount: 32
-        )
-        
-        let result = derivedKey.withUnsafeBytes { Data($0) }
-        // Final derived key ready
-        return result
     }
     
     // Direct version that doesn't try to add prefixes
@@ -452,15 +390,8 @@ struct NostrProtocol {
         // Convert SharedSecret to Data
         let sharedSecretData = sharedSecret.withUnsafeBytes { Data($0) }
         
-        // Derive key using HKDF for NIP-44 v2
+        // Return raw ECDH shared secret; HKDF is applied by deriveNIP44V2Key
-        let derivedKey = HKDF<CryptoKit.SHA256>.deriveKey(
+        return sharedSecretData
-            inputKeyMaterial: SymmetricKey(data: sharedSecretData),
-            salt: "nip44-v2".data(using: .utf8)!,
-            info: Data(),
-            outputByteCount: 32
-        )
-        
-        return derivedKey.withUnsafeBytes { Data($0) }
     }
     
     private static func randomizedTimestamp() -> Date {
@@ -537,7 +468,10 @@ struct NostrEvent: Codable {
         
         // Sign with Schnorr
         var messageBytes = [UInt8](eventIdHash)
-        var auxRand = [UInt8](repeating: 0, count: 32) // Zero auxiliary randomness for deterministic signing
+        var auxRand = [UInt8](repeating: 0, count: 32)
+        _ = auxRand.withUnsafeMutableBytes { ptr in
+            SecRandomCopyBytes(kSecRandomDefault, 32, ptr.baseAddress!)
+        }
         let schnorrSignature = try schnorrKey.signature(message: &messageBytes, auxiliaryRand: &auxRand)
         
         let signatureHex = schnorrSignature.dataRepresentation.hexEncodedString()
@@ -581,3 +515,32 @@ enum NostrError: Error {
     case signingFailed
     case encryptionFailed
 }
+
+// MARK: - NIP-44 v2 helpers (XChaCha20-Poly1305 + base64url)
+
+private extension NostrProtocol {
+    static func base64URLEncode(_ data: Data) -> String {
+        return data.base64EncodedString()
+            .replacingOccurrences(of: "+", with: "-")
+            .replacingOccurrences(of: "/", with: "_")
+            .replacingOccurrences(of: "=", with: "")
+    }
+
+    static func base64URLDecode(_ s: String) -> Data? {
+        var str = s
+        let pad = (4 - (str.count % 4)) % 4
+        if pad > 0 { str += String(repeating: "=", count: pad) }
+        str = str.replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/")
+        return Data(base64Encoded: str)
+    }
+
+    static func deriveNIP44V2Key(from sharedSecretData: Data) throws -> Data {
+        let derivedKey = HKDF<CryptoKit.SHA256>.deriveKey(
+            inputKeyMaterial: SymmetricKey(data: sharedSecretData),
+            salt: Data(),
+            info: "nip44-v2".data(using: .utf8)!,
+            outputByteCount: 32
+        )
+        return derivedKey.withUnsafeBytes { Data($0) }
+    }
+}

bitchat/Nostr/XChaCha20Poly1305Compat.swift

@@ -0,0 +1,116 @@
+import Foundation
+import CryptoKit
+
+/// Minimal XChaCha20-Poly1305 compatibility wrapper using CryptoKit's ChaChaPoly.
+/// Implements HChaCha20 to derive a subkey and reduces the 24-byte nonce to a 12-byte nonce
+/// as per XChaCha20 construction.
+enum XChaCha20Poly1305Compat {
+    struct SealBox {
+        let ciphertext: Data
+        let tag: Data
+    }
+
+    static func seal(plaintext: Data, key: Data, nonce24: Data, aad: Data? = nil) throws -> SealBox {
+        precondition(key.count == 32, "XChaCha20 key must be 32 bytes")
+        precondition(nonce24.count == 24, "XChaCha20 nonce must be 24 bytes")
+
+        let subkey = hchacha20(key: key, nonce16: nonce24.prefix(16))
+        let nonce12 = derive12ByteNonce(from24: nonce24)
+        let chachaKey = SymmetricKey(data: subkey)
+        let nonce = try ChaChaPoly.Nonce(data: nonce12)
+        let sealed = try ChaChaPoly.seal(plaintext, using: chachaKey, nonce: nonce, authenticating: aad ?? Data())
+        return SealBox(ciphertext: sealed.ciphertext, tag: sealed.tag)
+    }
+
+    static func open(ciphertext: Data, tag: Data, key: Data, nonce24: Data, aad: Data? = nil) throws -> Data {
+        precondition(key.count == 32, "XChaCha20 key must be 32 bytes")
+        precondition(nonce24.count == 24, "XChaCha20 nonce must be 24 bytes")
+
+        let subkey = hchacha20(key: key, nonce16: nonce24.prefix(16))
+        let nonce12 = derive12ByteNonce(from24: nonce24)
+        let chachaKey = SymmetricKey(data: subkey)
+        let box = try ChaChaPoly.SealedBox(nonce: ChaChaPoly.Nonce(data: nonce12), ciphertext: ciphertext, tag: tag)
+        return try ChaChaPoly.open(box, using: chachaKey, authenticating: aad ?? Data())
+    }
+
+    // MARK: - Internals
+
+    private static func derive12ByteNonce(from24 nonce24: Data) -> Data {
+        // XChaCha20-Poly1305: 12-byte nonce = 4 zero bytes || last 8 bytes of the 24-byte nonce
+        var out = Data(count: 12)
+        out.replaceSubrange(0..<4, with: [0, 0, 0, 0])
+        out.replaceSubrange(4..<12, with: nonce24.suffix(8))
+        return out
+    }
+
+    private static func hchacha20(key: Data, nonce16: Data) -> Data {
+        // HChaCha20 based on the original ChaCha20 core with a 16-byte nonce.
+        precondition(key.count == 32)
+        precondition(nonce16.count == 16)
+
+        // Constants "expand 32-byte k"
+        var state: [UInt32] = [
+            0x61707865, 0x3320646e, 0x79622d32, 0x6b206574,
+            // key (8 words)
+            key.loadLEWord(0), key.loadLEWord(4), key.loadLEWord(8), key.loadLEWord(12),
+            key.loadLEWord(16), key.loadLEWord(20), key.loadLEWord(24), key.loadLEWord(28),
+            // nonce (4 words)
+            nonce16.loadLEWord(0), nonce16.loadLEWord(4), nonce16.loadLEWord(8), nonce16.loadLEWord(12)
+        ]
+
+        // 20 rounds (10 double rounds)
+        for _ in 0..<10 {
+            // Column rounds
+            quarterRound(&state, 0, 4, 8, 12)
+            quarterRound(&state, 1, 5, 9, 13)
+            quarterRound(&state, 2, 6, 10, 14)
+            quarterRound(&state, 3, 7, 11, 15)
+            // Diagonal rounds
+            quarterRound(&state, 0, 5, 10, 15)
+            quarterRound(&state, 1, 6, 11, 12)
+            quarterRound(&state, 2, 7, 8, 13)
+            quarterRound(&state, 3, 4, 9, 14)
+        }
+
+        // Output subkey: state[0..3] and state[12..15]
+        var out = Data(count: 32)
+        out.storeLEWord(state[0], at: 0)
+        out.storeLEWord(state[1], at: 4)
+        out.storeLEWord(state[2], at: 8)
+        out.storeLEWord(state[3], at: 12)
+        out.storeLEWord(state[12], at: 16)
+        out.storeLEWord(state[13], at: 20)
+        out.storeLEWord(state[14], at: 24)
+        out.storeLEWord(state[15], at: 28)
+        return out
+    }
+
+    private static func quarterRound(_ s: inout [UInt32], _ a: Int, _ b: Int, _ c: Int, _ d: Int) {
+        s[a] = s[a] &+ s[b]; s[d] ^= s[a]; s[d] = (s[d] << 16) | (s[d] >> 16)
+        s[c] = s[c] &+ s[d]; s[b] ^= s[c]; s[b] = (s[b] << 12) | (s[b] >> 20)
+        s[a] = s[a] &+ s[b]; s[d] ^= s[a]; s[d] = (s[d] << 8)  | (s[d] >> 24)
+        s[c] = s[c] &+ s[d]; s[b] ^= s[c]; s[b] = (s[b] << 7)  | (s[b] >> 25)
+    }
+}
+
+private extension Data {
+    func loadLEWord(_ offset: Int) -> UInt32 {
+        let range = offset..<(offset+4)
+        let bytes = self[range]
+        return bytes.withUnsafeBytes { ptr -> UInt32 in
+            let b = ptr.bindMemory(to: UInt8.self)
+            return UInt32(b[0]) | (UInt32(b[1]) << 8) | (UInt32(b[2]) << 16) | (UInt32(b[3]) << 24)
+        }
+    }
+
+    mutating func storeLEWord(_ value: UInt32, at offset: Int) {
+        let bytes: [UInt8] = [
+            UInt8(value & 0xff),
+            UInt8((value >> 8) & 0xff),
+            UInt8((value >> 16) & 0xff),
+            UInt8((value >> 24) & 0xff)
+        ]
+        replaceSubrange(offset..<(offset+4), with: bytes)
+    }
+}
+