# System.Security

``` diff
 namespace System.Security {
+    public interface IStackWalk {
+        void Assert();
+        void Demand();
+        void Deny();
+        void PermitOnly();
+    }
+    public class PermissionSet : ICollection, IDeserializationCallback, IEnumerable, ISecurityEncodable, IStackWalk {
+        public PermissionSet(PermissionState state);
+        public PermissionSet(PermissionSet permSet);
+        public virtual int Count { get; }
+        public virtual bool IsReadOnly { get; }
+        public virtual bool IsSynchronized { get; }
+        public virtual object SyncRoot { get; }
+        public IPermission AddPermission(IPermission perm);
+        protected virtual IPermission AddPermissionImpl(IPermission perm);
+        public void Assert();
+        public bool ContainsNonCodeAccessPermissions();
+        public static byte[] ConvertPermissionSet(string inFormat, byte[] inData, string outFormat);
+        public virtual PermissionSet Copy();
+        public virtual void CopyTo(Array array, int index);
+        public void Demand();
+        public void Deny();
+        public override bool Equals(object o);
+        public virtual void FromXml(SecurityElement et);
+        public IEnumerator GetEnumerator();
+        protected virtual IEnumerator GetEnumeratorImpl();
+        public override int GetHashCode();
+        public IPermission GetPermission(Type permClass);
+        protected virtual IPermission GetPermissionImpl(Type permClass);
+        public PermissionSet Intersect(PermissionSet other);
+        public bool IsEmpty();
+        public bool IsSubsetOf(PermissionSet target);
+        public bool IsUnrestricted();
+        public void PermitOnly();
+        public IPermission RemovePermission(Type permClass);
+        protected virtual IPermission RemovePermissionImpl(Type permClass);
+        public static void RevertAssert();
+        public IPermission SetPermission(IPermission perm);
+        protected virtual IPermission SetPermissionImpl(IPermission perm);
+        void System.Runtime.Serialization.IDeserializationCallback.OnDeserialization(object sender);
+        public override string ToString();
+        public virtual SecurityElement ToXml();
+        public PermissionSet Union(PermissionSet other);
+    }
 }
```