LDK MCP Server

Instructions

Implementation Reference

• src/tools/generateMnemonic.ts:26-293 (handler)

  The main tool handler (execute function) that processes input args, generates BIP39 mnemonic and seed using WalletService, formats response with JSON including mnemonic, seed hex, word count, and embedded SwiftUI example code for secure mnemonic handling.

    execute: async (args: any): Promise<ToolResult> => {
      try {
        // Convert wordCount to strength if provided
        let strength = args.strength;
        if (args.wordCount) {
          strength = args.wordCount === 12 ? 128 : 256;
        }
        
        const mnemonic = walletService.generateMnemonic(strength || 256);
        const seedBuffer = walletService.mnemonicToSeed(mnemonic);
        const wordCount = mnemonic.split(' ').length;
  
        return {
          content: [{
            type: 'text',
            text: JSON.stringify({
              success: true,
              mnemonic,
              wordCount,
              seed: seedBuffer.toString('hex'),
              swiftExample: `
  // Swift code for secure mnemonic generation in your iOS app
  import SwiftUI
  import CryptoKit
  import LightningDevKit
  
  class MnemonicGenerator {
      enum MnemonicLength: Int {
          case words12 = 128
          case words24 = 256
          
          var wordCount: Int {
              switch self {
              case .words12: return 12
              case .words24: return 24
              }
          }
      }
      
      static func generateMnemonic(length: MnemonicLength = .words24) throws -> [String] {
          // Generate entropy
          let entropyBytes = length.rawValue / 8
          var entropy = Data(count: entropyBytes)
          let result = entropy.withUnsafeMutableBytes { bytes in
              SecRandomCopyBytes(kSecRandomDefault, entropyBytes, bytes.baseAddress!)
          }
          
          guard result == errSecSuccess else {
              throw WalletError.entropyGenerationFailed
          }
          
          // Convert to mnemonic
          let mnemonic = Mnemonic.toMnemonic(entropy: [UInt8](entropy))
          guard let words = mnemonic else {
              throw WalletError.mnemonicGenerationFailed
          }
          
          return words.components(separatedBy: " ")
      }
      
      static func mnemonicToSeed(words: [String], passphrase: String = "") -> Data {
          let mnemonic = words.joined(separator: " ")
          let seed = Mnemonic.toSeed(phrase: mnemonic, password: passphrase)
          return Data(seed)
      }
  }
  
  // SwiftUI view for secure mnemonic display
  struct MnemonicSetupView: View {
      @State private var mnemonicWords: [String] = []
      @State private var currentStep: SetupStep = .generate
      @State private var verificationWords: Set<Int> = []
      @State private var verificationInput: [Int: String] = [:]
      @State private var showError = false
      
      enum SetupStep {
          case generate
          case display
          case verify
          case complete
      }
      
      var body: some View {
          VStack(spacing: 0) {
              // Progress indicator
              ProgressBar(currentStep: currentStep)
                  .padding()
              
              // Content
              Group {
                  switch currentStep {
                  case .generate:
                      GenerateView(onGenerate: generateMnemonic)
                      
                  case .display:
                      DisplayView(words: mnemonicWords, onContinue: {
                          setupVerification()
                          currentStep = .verify
                      })
                      
                  case .verify:
                      VerifyView(
                          words: mnemonicWords,
                          verificationIndices: Array(verificationWords),
                          verificationInput: $verificationInput,
                          onVerify: verifyMnemonic
                      )
                      
                  case .complete:
                      CompleteView()
                  }
              }
              .padding()
              
              Spacer()
          }
          .navigationTitle("Wallet Setup")
          .navigationBarBackButtonHidden(currentStep != .generate)
          .alert("Verification Failed", isPresented: $showError) {
              Button("Try Again") { }
          } message: {
              Text("Please check the words and try again.")
          }
      }
      
      func generateMnemonic() {
          do {
              mnemonicWords = try MnemonicGenerator.generateMnemonic()
              currentStep = .display
          } catch {
              // Handle error
          }
      }
      
      func setupVerification() {
          // Select random words to verify
          verificationWords = Set((0..<mnemonicWords.count).shuffled().prefix(3))
          verificationInput = [:]
      }
      
      func verifyMnemonic() {
          var allCorrect = true
          
          for index in verificationWords {
              let expectedWord = mnemonicWords[index]
              let inputWord = verificationInput[index]?.lowercased().trimmingCharacters(in: .whitespacesAndNewlines)
              
              if inputWord != expectedWord {
                  allCorrect = false
                  break
              }
          }
          
          if allCorrect {
              saveMnemonicSecurely()
              currentStep = .complete
          } else {
              showError = true
          }
      }
      
      func saveMnemonicSecurely() {
          // Save to keychain with biometric protection
          Task {
              do {
                  let seed = MnemonicGenerator.mnemonicToSeed(words: mnemonicWords)
                  _ = try await BiometricLightningAuth.protectSeedWithBiometrics(seed: seed)
                  
                  // Clear mnemonic from memory
                  mnemonicWords = []
                  verificationInput = [:]
              } catch {
                  // Handle error
              }
          }
      }
  }
  
  struct DisplayView: View {
      let words: [String]
      let onContinue: () -> Void
      @State private var hasScreenshot = false
      
      var body: some View {
          VStack(spacing: 24) {
              // Warning
              VStack(spacing: 12) {
                  Image(systemName: "exclamationmark.triangle.fill")
                      .font(.largeTitle)
                      .foregroundColor(.orange)
                  
                  Text("Write Down Your Recovery Phrase")
                      .font(.title2)
                      .fontWeight(.semibold)
                  
                  Text("Write these words on paper. Never share them with anyone.")
                      .font(.callout)
                      .foregroundColor(.secondary)
                      .multilineTextAlignment(.center)
              }
              
              // Mnemonic grid
              LazyVGrid(columns: [
                  GridItem(.flexible()),
                  GridItem(.flexible()),
                  GridItem(.flexible())
              ], spacing: 12) {
                  ForEach(Array(words.enumerated()), id: \\.offset) { index, word in
                      WordCell(number: index + 1, word: word)
                  }
              }
              .padding()
              .background(Color(UIColor.secondarySystemBackground))
              .cornerRadius(12)
              
              // Screenshot warning
              Toggle("I have written down all words", isOn: $hasScreenshot)
                  .toggleStyle(CheckboxToggleStyle())
              
              Button(action: onContinue) {
                  Text("Continue to Verification")
                      .frame(maxWidth: .infinity)
              }
              .buttonStyle(.borderedProminent)
              .controlSize(.large)
              .disabled(!hasScreenshot)
          }
      }
  }
  
  struct WordCell: View {
      let number: Int
      let word: String
      
      var body: some View {
          HStack(spacing: 8) {
              Text("\\(number).")
                  .font(.caption)
                  .foregroundColor(.secondary)
                  .frame(width: 20, alignment: .trailing)
              
              Text(word)
                  .font(.system(.body, design: .monospaced))
                  .fontWeight(.medium)
          }
          .padding(.vertical, 8)
          .padding(.horizontal, 12)
          .frame(maxWidth: .infinity, alignment: .leading)
          .background(Color(UIColor.tertiarySystemBackground))
          .cornerRadius(8)
      }
  }`.trim()
            }, null, 2)
          }]
        };
      } catch (error) {
        return {
          content: [{
            type: 'text',
            text: JSON.stringify({
              success: false,
              error: error instanceof Error ? error.message : 'Unknown error'
            }, null, 2)
          }],
          isError: true
        };
      }
    }

• src/tools/generateMnemonic.ts:9-25 (schema)

  Input schema defining optional parameters for mnemonic strength (128/256 bits) or word count (12/24 words).

  inputSchema: {
    type: 'object',
    properties: {
      strength: {
        type: 'number',
        enum: [128, 256],
        description: 'Mnemonic strength (128 = 12 words, 256 = 24 words)',
        default: 256
      },
      wordCount: {
        type: 'number',
        enum: [12, 24],
        description: 'Number of words in mnemonic (12 or 24)',
        default: 24
      }
    }
  },

• src/tools/generateMnemonic.ts:6-7 (registration)

  Tool registration defining the name 'ldk_generate_mnemonic', description, schema, and handler.

  export const generateMnemonicTool: Tool = {
    name: 'ldk_generate_mnemonic',

• src/services/walletService.ts:19-21 (helper)

  WalletService helper method that generates the BIP39 mnemonic string using the bip39 library.

  generateMnemonic(strength: 128 | 256 = 256): string {
    return bip39.generateMnemonic(strength);
  }

• src/services/walletService.ts:23-28 (helper)

  WalletService helper method that converts mnemonic to seed buffer using bip39, with validation.

  mnemonicToSeed(mnemonic: string, passphrase: string = ''): Buffer {
    if (!bip39.validateMnemonic(mnemonic)) {
      throw new Error('Invalid mnemonic');
    }
    return bip39.mnemonicToSeedSync(mnemonic, passphrase);
  }