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.
31 using System.Globalization;
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 ();
134 public void Dispose ()
137 // don't call clear because we could be either in read-only
138 // or already disposed - but DO CLEAR the data
140 Array.Clear (data, 0, data.Length);
146 public void InsertAt (int index, char c)
149 throw new ObjectDisposedException ("SecureString");
151 throw new InvalidOperationException (Locale.GetText (
152 "SecureString is read-only."));
154 if ((index < 0) || (index > length))
155 throw new ArgumentOutOfRangeException ("index", "< 0 || > length");
156 // insert increments length
157 if (length >= MaxSize) {
158 string msg = Locale.GetText ("Maximum string size is '{0}'.", MaxSize);
159 throw new ArgumentOutOfRangeException ("index", msg);
164 Alloc (++length, true);
166 Buffer.BlockCopy (data, n, data, n + 2, data.Length - 2);
167 data[n++] = (byte) (c >> 8);
175 public bool IsReadOnly ()
178 throw new ObjectDisposedException ("SecureString");
182 public void MakeReadOnly ()
187 public void RemoveAt (int index)
190 throw new ObjectDisposedException ("SecureString");
192 throw new InvalidOperationException (Locale.GetText (
193 "SecureString is read-only."));
195 if ((index < 0) || (index >= length))
196 throw new ArgumentOutOfRangeException ("index", "< 0 || > length");
200 Buffer.BlockCopy (data, index + 1, data, index, data.Length - index - 1);
201 Alloc (--length, true);
208 public void SetAt (int index, char c)
211 throw new ObjectDisposedException ("SecureString");
213 throw new InvalidOperationException (Locale.GetText (
214 "SecureString is read-only."));
216 if ((index < 0) || (index >= length))
217 throw new ArgumentOutOfRangeException ("index", "< 0 || > length");
222 data[n++] = (byte) (c >> 8);
230 // internal/private stuff
232 [MonoTODO ("ProtectedMemory is in System.Security.dll - move this into the runtime/icall")]
233 private void Encrypt ()
235 if ((data != null) && (data.Length > 0)) {
236 // ProtectedMemory.Protect (data, MemoryProtectionScope.SameProcess);
240 [MonoTODO ("ProtectedMemory is in System.Security.dll - move this into the runtime/icall")]
241 private void Decrypt ()
243 if ((data != null) && (data.Length > 0)) {
244 // ProtectedMemory.Unprotect (data, MemoryProtectionScope.SameProcess);
248 // note: realloc only work for bigger buffers. Clear will
249 // reset buffers to default (and small) size.
250 private void Alloc (int length, bool realloc)
252 if ((length < 0) || (length > MaxSize))
253 throw new ArgumentOutOfRangeException ("length", "< 0 || > 65536");
255 // (size / blocksize) + 1 * blocksize
256 // where size = length * 2 (unicode) and blocksize == 16 (ProtectedMemory)
257 // length * 2 (unicode) / 16 (blocksize)
258 int size = (length >> 3) + (((length & 0x7) == 0) ? 0 : 1) << 4;
260 // is re-allocation necessary ? (i.e. grow or shrink
261 // but do not re-allocate the same amount of memory)
262 if (realloc && (data != null) && (size == data.Length))
267 byte[] newdata = new byte[size];
268 Array.Copy (data, 0, newdata, 0, Math.Min (data.Length, newdata.Length));
269 Array.Clear (data, 0, data.Length);
272 data = new byte[size];
276 // dangerous method (put a LinkDemand on it)
277 internal byte[] GetBuffer ()
279 byte[] secret = new byte[length << 1];
282 Buffer.BlockCopy (data, 0, secret, 0, secret.Length);
287 // NOTE: CALLER IS RESPONSIBLE TO ZEROIZE THE DATA