Initial commit: BARON SSO 샘플 (WebView OIDC PKCE 인증 라이브러리 + 데모 앱)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

BaronSoftware.SSO/OIDC/PKCEUtil.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace BaronSoftware.SSO
+{
+    internal static class PKCEUtil
+    {
+        public static string NewVerifier() => B64Url(RandomNumberGenerator.GetBytes(32));
+        public static string RandomToken() => B64Url(RandomNumberGenerator.GetBytes(16));
+        public static string Challenge(string verifier) => B64Url(SHA256.HashData(Encoding.ASCII.GetBytes(verifier)));
+        private static string B64Url(byte[] bytes) => Convert.ToBase64String(bytes).TrimEnd('=').Replace('+', '-').Replace('/', '_');
+        public static Dictionary<string, string> ParseQuery(string uri)
+        {
+            var result = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            var query = new Uri(uri).Query.TrimStart('?');
+            foreach (var pair in query.Split('&', StringSplitOptions.RemoveEmptyEntries))
+            {
+                var kv = pair.Split('=', 2);
+                result[Uri.UnescapeDataString(kv[0])] = kv.Length > 1 ? Uri.UnescapeDataString(kv[1]) : string.Empty;
+            }
+            return result;
+        }
+    }
+}