Replace the JavaScript mobile app with a native Swift iOS wallet

2026-09-19 13:33:11 +08:00
parent d80b58b704
commit 3e1a39d4d7
79 changed files with 25482 additions and 4023 deletions
@@ -0,0 +1,92 @@
+import CryptoKit
+import Foundation
+
+/// BIP-32 key derivation for the XRP account path `m/44'/144'/0'/0/0`. The
+/// first three steps are hardened, the last two are not, so both cases are
+/// supported (hardened steps sign with the parent private key, normal steps
+/// with the parent public key).
+enum BIP32 {
+  static let hardenedBit: UInt32 = 0x8000_0000
+
+  /// Standard XRP derivation path: 44' / 144' / 0' / 0 / 0.
+  static let xrpPath: [UInt32] = [
+    hardenedBit | 44,
+    hardenedBit | 144,
+    hardenedBit | 0,
+    0,
+    0,
+  ]
+
+  struct Key {
+    var privateKey: [UInt8]
+    var chainCode: [UInt8]
+    var publicKey: [UInt8]
+  }
+
+  static func masterKey(fromSeed seed: [UInt8]) -> Key? {
+    let derived = hmac(key: Array("Bitcoin seed".utf8), data: seed)
+    guard derived.count == 64 else { return nil }
+    let privateKey = Array(derived[0..<32])
+    guard isValidScalar(privateKey),
+          let publicKey = Secp256k1Backend.publicKey?(Data(privateKey)) else { return nil }
+    return Key(privateKey: privateKey,
+               chainCode: Array(derived[32..<64]),
+               publicKey: Array(publicKey))
+  }
+
+  static func derive(_ path: [UInt32], from key: Key) -> Key? {
+    var current = key
+    for index in path {
+      guard let next = deriveChild(current, index: index) else { return nil }
+      current = next
+    }
+    return current
+  }
+
+  private static func deriveChild(_ parent: Key, index: UInt32) -> Key? {
+    let isHardened = index & hardenedBit != 0
+
+    var data: [UInt8] = []
+    if isHardened {
+      data.append(0x00)
+      data += parent.privateKey
+    } else {
+      data += parent.publicKey
+    }
+    data += [
+      UInt8((index >> 24) & 0xff),
+      UInt8((index >> 16) & 0xff),
+      UInt8((index >> 8) & 0xff),
+      UInt8(index & 0xff),
+    ]
+
+    let derived = hmac(key: parent.chainCode, data: data)
+    guard derived.count == 64 else { return nil }
+    let left = Array(derived[0..<32])
+    guard isValidScalar(left),
+          let sum = Secp256k1Backend.addScalar?(Data(left), Data(parent.privateKey)) else { return nil }
+    let privateKey = Array(sum)
+    // The child public key is the same whether it is computed from the child
+    // private key or by point addition, so derive it directly.
+    guard isValidScalar(privateKey),
+          let publicKey = Secp256k1Backend.publicKey?(Data(privateKey)) else { return nil }
+
+    return Key(privateKey: privateKey,
+               chainCode: Array(derived[32..<64]),
+               publicKey: Array(publicKey))
+  }
+
+  /// A key is usable when 0 < key < the secp256k1 group order.
+  private static func isValidScalar(_ bytes: [UInt8]) -> Bool {
+    guard bytes.count == 32 else { return false }
+    let orderHex = "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141"
+    guard let order = Hex.decode(orderHex) else { return false }
+    if bytes.allSatisfy({ $0 == 0 }) { return false }
+    for (left, right) in zip(bytes, order) where left != right { return left < right }
+    return false
+  }
+
+  private static func hmac(key: [UInt8], data: [UInt8]) -> [UInt8] {
+    Array(HMAC<SHA512>.authenticationCode(for: Data(data), using: SymmetricKey(data: Data(key))))
+  }
+}