2 // System.Security.SecureString class
5 // Sebastien Pouliot <sebastien@ximian.com>
7 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
9 // Permission is hereby granted, free of charge, to any person obtaining
10 // a copy of this software and associated documentation files (the
11 // "Software"), to deal in the Software without restriction, including
12 // without limitation the rights to use, copy, modify, merge, publish,
13 // distribute, sublicense, and/or sell copies of the Software, and to
14 // permit persons to whom the Software is furnished to do so, subject to
15 // the following conditions:
17 // The above copyright notice and this permission notice shall be
18 // included in all copies or substantial portions of the Software.
20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
29 using System.Globalization;
30 using System.Reflection;
31 using System.Runtime.CompilerServices;
32 using System.Runtime.InteropServices;
33 using System.Runtime.ConstrainedExecution;
34 using System.Security.Cryptography;
35 using System.Security.Permissions;
37 namespace System.Security {
39 [MonoTODO ("work in progress - encryption is missing")]
40 public sealed class SecureString : CriticalFinalizerObject, IDisposable {
42 private const int BlockSize = 16;
43 private const int MaxSize = 65536;
46 private bool disposed;
47 private bool read_only;
50 static SecureString ()
52 // ProtectedMemory has been moved to System.Security.dll
53 // we use reflection to call it (if available) or we'll
57 public SecureString ()
59 Alloc (BlockSize >> 1, false);
62 [CLSCompliant (false)]
63 public unsafe SecureString (char* value, int length)
66 throw new ArgumentNullException ("value");
67 if ((length < 0) || (length > MaxSize))
68 throw new ArgumentOutOfRangeException ("length", "< 0 || > 65536");
70 this.length = length; // real length
71 Alloc (length, false);
73 for (int i = 0; i < length; i++) {
75 data[n++] = (byte) (c >> 8);
86 throw new ObjectDisposedException ("SecureString");
91 public void AppendChar (char c)
94 throw new ObjectDisposedException ("SecureString");
96 throw new InvalidOperationException (Locale.GetText (
97 "SecureString is read-only."));
99 if (length == MaxSize)
100 throw new ArgumentOutOfRangeException ("length", "> 65536");
105 Alloc (++length, true);
106 data[n++] = (byte) (c >> 8);
107 data[n++] = (byte) c;
117 throw new ObjectDisposedException ("SecureString");
119 throw new InvalidOperationException (Locale.GetText (
120 "SecureString is read-only."));
123 Array.Clear (data, 0, data.Length);
127 public SecureString Copy ()
129 SecureString ss = new SecureString ();
130 ss.data = (byte[]) data.Clone ();
135 public void Dispose ()
138 // don't call clear because we could be either in read-only
139 // or already disposed - but DO CLEAR the data
141 Array.Clear (data, 0, data.Length);
147 public void InsertAt (int index, char c)
150 throw new ObjectDisposedException ("SecureString");
152 throw new InvalidOperationException (Locale.GetText (
153 "SecureString is read-only."));
155 if ((index < 0) || (index > length))
156 throw new ArgumentOutOfRangeException ("index", "< 0 || > length");
157 // insert increments length
158 if (length >= MaxSize) {
159 string msg = Locale.GetText ("Maximum string size is '{0}'.", MaxSize);
160 throw new ArgumentOutOfRangeException ("index", msg);
165 Alloc (++length, true);
167 Buffer.BlockCopy (data, n, data, n + 2, data.Length - n - 2);
168 data[n++] = (byte) (c >> 8);
176 public bool IsReadOnly ()
179 throw new ObjectDisposedException ("SecureString");
183 public void MakeReadOnly ()
188 public void RemoveAt (int index)
191 throw new ObjectDisposedException ("SecureString");
193 throw new InvalidOperationException (Locale.GetText (
194 "SecureString is read-only."));
196 if ((index < 0) || (index >= length))
197 throw new ArgumentOutOfRangeException ("index", "< 0 || > length");
201 Buffer.BlockCopy (data, index + 1, data, index, data.Length - index - 1);
202 Alloc (--length, true);
209 public void SetAt (int index, char c)
212 throw new ObjectDisposedException ("SecureString");
214 throw new InvalidOperationException (Locale.GetText (
215 "SecureString is read-only."));
217 if ((index < 0) || (index >= length))
218 throw new ArgumentOutOfRangeException ("index", "< 0 || > length");
223 data[n++] = (byte) (c >> 8);
231 // internal/private stuff
233 // [MethodImplAttribute(MethodImplOptions.InternalCall)]
234 // extern static void EncryptInternal (byte [] data, object scope);
236 // [MethodImplAttribute(MethodImplOptions.InternalCall)]
237 // extern static void DecryptInternal (byte [] data, object scope);
239 // static readonly object scope = Enum.Parse (
240 // Assembly.Load (Consts.AssemblySystem_Security)
241 // .GetType ("System.Security.Cryptography.MemoryProtectionScope"), "SameProcess");
243 // Note that ProtectedMemory is not supported on non-Windows environment right now.
244 private void Encrypt ()
246 if ((data != null) && (data.Length > 0)) {
247 // It somehow causes nunit test breakage
248 // EncryptInternal (data, scope);
252 // Note that ProtectedMemory is not supported on non-Windows environment right now.
253 private void Decrypt ()
255 if ((data != null) && (data.Length > 0)) {
256 // It somehow causes nunit test breakage
257 // DecryptInternal (data, scope);
261 // note: realloc only work for bigger buffers. Clear will
262 // reset buffers to default (and small) size.
263 private void Alloc (int length, bool realloc)
265 if ((length < 0) || (length > MaxSize))
266 throw new ArgumentOutOfRangeException ("length", "< 0 || > 65536");
268 // (size / blocksize) + 1 * blocksize
269 // where size = length * 2 (unicode) and blocksize == 16 (ProtectedMemory)
270 // length * 2 (unicode) / 16 (blocksize)
271 int size = (length >> 3) + (((length & 0x7) == 0) ? 0 : 1) << 4;
273 // is re-allocation necessary ? (i.e. grow or shrink
274 // but do not re-allocate the same amount of memory)
275 if (realloc && (data != null) && (size == data.Length))
280 byte[] newdata = new byte[size];
281 Array.Copy (data, 0, newdata, 0, Math.Min (data.Length, newdata.Length));
282 Array.Clear (data, 0, data.Length);
285 data = new byte[size];
289 // dangerous method (put a LinkDemand on it)
290 internal byte[] GetBuffer ()
292 byte[] secret = new byte[length << 1];
295 Buffer.BlockCopy (data, 0, secret, 0, secret.Length);
300 // NOTE: CALLER IS RESPONSIBLE TO ZEROIZE THE DATA