Initial public API refactoring experiment

submodules/TelegramCore/Sources/TelegramEngine/SecureId/SecureIdPadding.swift

@@ -0,0 +1,26 @@
+import Foundation
+
+func paddedSecureIdData(_ data: Data) -> Data {
+    var paddingCount = Int(47 + arc4random_uniform(255 - 47))
+    paddingCount -= ((data.count + paddingCount) % 16)
+    var result = Data(count: paddingCount + data.count)
+    result.withUnsafeMutableBytes { (bytes: UnsafeMutablePointer<UInt8>) -> Void in
+        bytes.advanced(by: 0).pointee = UInt8(paddingCount)
+        arc4random_buf(bytes.advanced(by: 1), paddingCount - 1)
+        data.withUnsafeBytes { (source: UnsafePointer<UInt8>) -> Void in
+            memcpy(bytes.advanced(by: paddingCount), source, data.count)
+        }
+    }
+    return result
+}
+
+func unpaddedSecureIdData(_ data: Data) -> Data? {
+    var paddingCount: UInt8 = 0
+    data.copyBytes(to: &paddingCount, count: 1)
+    
+    if paddingCount < 0 || paddingCount > data.count {
+        return nil
+    }
+    
+    return data.subdata(in: Int(paddingCount) ..< data.count)
+}