Replace the JavaScript mobile app with a native Swift iOS wallet

apps/ios/Koins/Support/Base58.swift

@@ -0,0 +1,76 @@
+import Foundation
+
+/// Base58 with the XRP Ledger alphabet and Base58Check helpers.
+enum XRPBase58 {
+  static let alphabet: [Character] = Array("rpshnaf39wBUDNEGHJKLM4PQRST7VWXYZ2bcdeCg65jkm8oFqi1tuvAxyz")
+
+  private static let valueOf: [Character: Int] = {
+    var map: [Character: Int] = [:]
+    for (index, character) in alphabet.enumerated() { map[character] = index }
+    return map
+  }()
+
+  static func encode(_ bytes: [UInt8]) -> String {
+    var zeros = 0
+    for byte in bytes {
+      if byte == 0 { zeros += 1 } else { break }
+    }
+
+    var digits: [Int] = []
+    for byte in bytes[zeros...] {
+      var carry = Int(byte)
+      for index in digits.indices {
+        carry += digits[index] << 8
+        digits[index] = carry % 58
+        carry /= 58
+      }
+      while carry > 0 {
+        digits.append(carry % 58)
+        carry /= 58
+      }
+    }
+
+    var output = String(repeating: String(alphabet[0]), count: zeros)
+    for digit in digits.reversed() { output.append(alphabet[digit]) }
+    return output
+  }
+
+  static func decode(_ string: String) throws -> [UInt8] {
+    let characters = Array(string)
+    var zeros = 0
+    for character in characters {
+      if character == alphabet[0] { zeros += 1 } else { break }
+    }
+
+    var bytes: [Int] = []
+    for character in characters[zeros...] {
+      guard let value = valueOf[character] else { throw XRPError.invalidBase58 }
+      var carry = value
+      for index in bytes.indices {
+        carry += bytes[index] * 58
+        bytes[index] = carry & 0xff
+        carry >>= 8
+      }
+      while carry > 0 {
+        bytes.append(carry & 0xff)
+        carry >>= 8
+      }
+    }
+
+    return [UInt8](repeating: 0, count: zeros) + bytes.reversed().map { UInt8($0) }
+  }
+
+  static func checkEncode(version: [UInt8], payload: [UInt8]) -> String {
+    let body = version + payload
+    return encode(body + XRPHash.checksum(body))
+  }
+
+  static func checkDecode(_ string: String, versionLength: Int) throws -> [UInt8] {
+    let decoded = try decode(string)
+    guard decoded.count > versionLength + 4 else { throw XRPError.invalidAddress }
+    let body = Array(decoded[0..<(decoded.count - 4)])
+    let checksum = Array(decoded[(decoded.count - 4)...])
+    guard XRPHash.checksum(body) == checksum else { throw XRPError.invalidAddress }
+    return Array(body[versionLength...])
+  }
+}