Dactyloidae iOS initial commit

mobile/ios/Shared/Extensions/HexExtensions.swift

@@ -0,0 +1,70 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+import Foundation
+
+extension String {
+    public var hexDecodedData: Data {
+        // Convert to a CString and make sure it has an even number of characters (terminating 0 is included, so we
+        // check for uneven!)
+        guard let cString = self.cString(using: String.Encoding.ascii), (cString.count % 2) == 1 else {
+            return Data()
+        }
+
+        var result = Data(capacity: (cString.count - 1) / 2)
+        for i in stride(from: 0, to: (cString.count - 1), by: 2) {
+            guard let l = hexCharToByte(cString[i]), let r = hexCharToByte(cString[i+1]) else {
+                return Data()
+            }
+            var value: UInt8 = (l << 4) | r
+            result.append(&value, count: MemoryLayout.size(ofValue: value))
+        }
+        return result
+    }
+
+    private func hexCharToByte(_ c: CChar) -> UInt8? {
+        if c >= 48 && c <= 57 { // 0 - 9
+            return UInt8(c - 48)
+        }
+        if c >= 97 && c <= 102 { // a - f
+            return UInt8(10) + UInt8(c - 97)
+        }
+        if c >= 65 && c <= 70 { // A - F
+            return UInt8(10) + UInt8(c - 65)
+        }
+        return nil
+    }
+}
+
+private let HexDigits: [String] = ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"]
+
+extension Data {
+    public var hexEncodedString: String {
+        var result = String()
+        result.reserveCapacity(count * 2)
+        withUnsafeBytes { (p: UnsafePointer<UInt8>) in
+            for i in 0..<count {
+                result.append(HexDigits[Int((p[i] & 0xf0) >> 4)])
+                result.append(HexDigits[Int(p[i] & 0x0f)])
+            }
+        }
+        return String(result)
+    }
+
+    public static func randomOfLength(_ length: UInt) -> Data? {
+        let length = Int(length)
+        var data = Data(count: length)
+        var result: Int32 = 0
+        data.withUnsafeMutableBytes { (p: UnsafeMutablePointer<UInt8>) in
+            result = SecRandomCopyBytes(kSecRandomDefault, length, p)
+        }
+        return result == 0 ? data : nil
+    }
+}
+
+extension Data {
+    public var base64EncodedString: String {
+        return self.base64EncodedString(options: NSData.Base64EncodingOptions())
+    }
+}