mcs/class/Mono.Security/Mono.Security.Cryptography/RSAManaged.cs

   1 //
   2 // RSAManaged.cs - Implements the RSA algorithm.
   3 //
   4 // Authors:
   5 //      Sebastien Pouliot (sebastien@ximian.com)
   6 //      Ben Maurer (bmaurer@users.sf.net)
   7 //
   8 // (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
   9 // Portions (C) 2003 Ben Maurer
  10 // Copyright (C) 2004,2006 Novell, Inc (http://www.novell.com)
  11 //
  12 // Key generation translated from Bouncy Castle JCE (http://www.bouncycastle.org/)
  13 // See bouncycastle.txt for license.
  14 //
  15 // Permission is hereby granted, free of charge, to any person obtaining
  16 // a copy of this software and associated documentation files (the
  17 // "Software"), to deal in the Software without restriction, including
  18 // without limitation the rights to use, copy, modify, merge, publish,
  19 // distribute, sublicense, and/or sell copies of the Software, and to
  20 // permit persons to whom the Software is furnished to do so, subject to
  21 // the following conditions:
  22 //
  23 // The above copyright notice and this permission notice shall be
  24 // included in all copies or substantial portions of the Software.
  25 //
  26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  33 //
  34
  35 using System;
  36 using System.Security.Cryptography;
  37 using System.Text;
  38
  39 using Mono.Math;
  40
  41 // Big chunks of code are coming from the original RSACryptoServiceProvider class.
  42 // The class was refactored to :
  43 // a.   ease integration of new hash algorithm (like MD2, RIPEMD160, ...);
  44 // b.   provide better support for the coming SSL implementation (requires
  45 //      EncryptValue/DecryptValue) with, or without, Mono runtime/corlib;
  46 // c.   provide an alternative RSA implementation for all Windows (like using
  47 //      OAEP without Windows XP).
  48
  49 namespace Mono.Security.Cryptography {
  50
  51 #if INSIDE_CORLIB
  52         internal
  53 #else
  54         public
  55 #endif
  56         class RSAManaged : RSA {
  57
  58                 private const int defaultKeySize = 1024;
  59
  60                 private bool isCRTpossible = false;
  61                 private bool keyBlinding = true;
  62                 private bool keypairGenerated = false;
  63                 private bool m_disposed = false;
  64
  65                 private BigInteger d;
  66                 private BigInteger p;
  67                 private BigInteger q;
  68                 private BigInteger dp;
  69                 private BigInteger dq;
  70                 private BigInteger qInv;
  71                 private BigInteger n;           // modulus
  72                 private BigInteger e;
  73
  74                 public RSAManaged () : this (defaultKeySize)
  75                 {
  76                 }
  77
  78                 public RSAManaged (int keySize)
  79                 {
  80                         LegalKeySizesValue = new KeySizes [1];
  81                         LegalKeySizesValue [0] = new KeySizes (384, 16384, 8);
  82                         base.KeySize = keySize;
  83                 }
  84
  85                 ~RSAManaged ()
  86                 {
  87                         // Zeroize private key
  88                         Dispose (false);
  89                 }
  90
  91                 private void GenerateKeyPair ()
  92                 {
  93                         // p and q values should have a length of half the strength in bits
  94                         int pbitlength = ((KeySize + 1) >> 1);
  95                         int qbitlength = (KeySize - pbitlength);
  96                         const uint uint_e = 17;
  97                         e = uint_e; // fixed
  98
  99                         // generate p, prime and (p-1) relatively prime to e
 100                         for (;;) {
 101                                 p = BigInteger.GeneratePseudoPrime (pbitlength);
 102                                 if (p % uint_e != 1)
 103                                         break;
 104                         }
 105                         // generate a modulus of the required length
 106                         for (;;) {
 107                                 // generate q, prime and (q-1) relatively prime to e,
 108                                 // and not equal to p
 109                                 for (;;) {
 110                                         q = BigInteger.GeneratePseudoPrime (qbitlength);
 111                                         if ((q % uint_e != 1) && (p != q))
 112                                                 break;
 113                                 }
 114
 115                                 // calculate the modulus
 116                                 n = p * q;
 117                                 if (n.BitCount () == KeySize)
 118                                         break;
 119
 120                                 // if we get here our primes aren't big enough, make the largest
 121                                 // of the two p and try again
 122                                 if (p < q)
 123                                         p = q;
 124                         }
 125
 126                         BigInteger pSub1 = (p - 1);
 127                         BigInteger qSub1 = (q - 1);
 128                         BigInteger phi = pSub1 * qSub1;
 129
 130                         // calculate the private exponent
 131                         d = e.ModInverse (phi);
 132
 133                         // calculate the CRT factors
 134                         dp = d % pSub1;
 135                         dq = d % qSub1;
 136                         qInv = q.ModInverse (p);
 137
 138                         keypairGenerated = true;
 139                         isCRTpossible = true;
 140
 141                         if (KeyGenerated != null)
 142                                 KeyGenerated (this, null);
 143                 }
 144
 145                 // overrides from RSA class
 146
 147                 public override int KeySize {
 148                         get {
 149                                 // in case keypair hasn't been (yet) generated
 150                                 if (keypairGenerated) {
 151                                         int ks = n.BitCount ();
 152                                         if ((ks & 7) != 0)
 153                                                 ks = ks + (8 - (ks & 7));
 154                                         return ks;
 155                                 }
 156                                 else
 157                                         return base.KeySize;
 158                         }
 159                 }
 160                 public override string KeyExchangeAlgorithm {
 161                         get { return "RSA-PKCS1-KeyEx"; }
 162                 }
 163
 164                 // note: when (if) we generate a keypair then it will have both
 165                 // the public and private keys
 166                 public bool PublicOnly {
 167                         get { return (keypairGenerated && ((d == null) || (n == null))); }
 168                 }
 169
 170                 public override string SignatureAlgorithm {
 171                         get { return "http://www.w3.org/2000/09/xmldsig#rsa-sha1"; }
 172                 }
 173
 174                 public override byte[] DecryptValue (byte[] rgb)
 175                 {
 176                         if (m_disposed)
 177                                 throw new ObjectDisposedException ("private key");
 178
 179                         // decrypt operation is used for signature
 180                         if (!keypairGenerated)
 181                                 GenerateKeyPair ();
 182
 183                         BigInteger input = new BigInteger (rgb);
 184                         BigInteger r = null;
 185
 186                         // we use key blinding (by default) against timing attacks
 187                         if (keyBlinding) {
 188                                 // x = (r^e * g) mod n
 189                                 // *new* random number (so it's timing is also random)
 190                                 r = BigInteger.GenerateRandom (n.BitCount ());
 191                                 input = r.ModPow (e, n) * input % n;
 192                         }
 193
 194                         BigInteger output;
 195                         // decrypt (which uses the private key) can be
 196                         // optimized by using CRT (Chinese Remainder Theorem)
 197                         if (isCRTpossible) {
 198                                 // m1 = c^dp mod p
 199                                 BigInteger m1 = input.ModPow (dp, p);
 200                                 // m2 = c^dq mod q
 201                                 BigInteger m2 = input.ModPow (dq, q);
 202                                 BigInteger h;
 203                                 if (m2 > m1) {
 204                                         // thanks to benm!
 205                                         h = p - ((m2 - m1) * qInv % p);
 206                                         output = m2 + q * h;
 207                                 } else {
 208                                         // h = (m1 - m2) * qInv mod p
 209                                         h = (m1 - m2) * qInv % p;
 210                                         // m = m2 + q * h;
 211                                         output = m2 + q * h;
 212                                 }
 213                         } else if (!PublicOnly) {
 214                                 // m = c^d mod n
 215                                 output = input.ModPow (d, n);
 216                         } else {
 217                                 throw new CryptographicException (Locale.GetText ("Missing private key to decrypt value."));
 218                         }
 219
 220                         if (keyBlinding) {
 221                                 // Complete blinding
 222                                 // x^e / r mod n
 223                                 output = output * r.ModInverse (n) % n;
 224                                 r.Clear ();
 225                         }
 226
 227                         // it's sometimes possible for the results to be a byte short
 228                         // and this can break some software (see #79502) so we 0x00 pad the result
 229                         byte[] result = GetPaddedValue (output, (KeySize >> 3));
 230                         // zeroize values
 231                         input.Clear ();
 232                         output.Clear ();
 233                         return result;
 234                 }
 235
 236                 public override byte[] EncryptValue (byte[] rgb)
 237                 {
 238                         if (m_disposed)
 239                                 throw new ObjectDisposedException ("public key");
 240
 241                         if (!keypairGenerated)
 242                                 GenerateKeyPair ();
 243
 244                         BigInteger input = new BigInteger (rgb);
 245                         BigInteger output = input.ModPow (e, n);
 246                         // it's sometimes possible for the results to be a byte short
 247                         // and this can break some software (see #79502) so we 0x00 pad the result
 248                         byte[] result = GetPaddedValue (output, (KeySize >> 3));
 249                         // zeroize value
 250                         input.Clear ();
 251                         output.Clear ();
 252                         return result;
 253                 }
 254
 255
 256
 257                 public override RSAParameters ExportParameters (bool includePrivateParameters)
 258                 {
 259                         if (m_disposed)
 260                                 throw new ObjectDisposedException (Locale.GetText ("Keypair was disposed"));
 261
 262                         if (!keypairGenerated)
 263                                 GenerateKeyPair ();
 264
 265                         RSAParameters param = new RSAParameters ();
 266                         param.Exponent = e.GetBytes ();
 267                         param.Modulus = n.GetBytes ();
 268                         if (includePrivateParameters) {
 269                                 // some parameters are required for exporting the private key
 270                                 if (d == null)
 271                                         throw new CryptographicException ("Missing private key");
 272                                 param.D = d.GetBytes ();
 273                                 // hack for bugzilla #57941 where D wasn't provided
 274                                 if (param.D.Length != param.Modulus.Length) {
 275                                         byte[] normalizedD = new byte [param.Modulus.Length];
 276                                         Buffer.BlockCopy (param.D, 0, normalizedD, (normalizedD.Length - param.D.Length), param.D.Length);
 277                                         param.D = normalizedD;
 278                                 }
 279                                 // but CRT parameters are optionals
 280                                 if ((p != null) && (q != null) && (dp != null) && (dq != null) && (qInv != null)) {
 281                                         // and we include them only if we have them all
 282                                         int length = (KeySize >> 4);
 283                                         param.P = GetPaddedValue (p, length);
 284                                         param.Q = GetPaddedValue (q, length);
 285                                         param.DP = GetPaddedValue (dp, length);
 286                                         param.DQ = GetPaddedValue (dq, length);
 287                                         param.InverseQ = GetPaddedValue (qInv, length);
 288                                 }
 289                         }
 290                         return param;
 291                 }
 292
 293                 public override void ImportParameters (RSAParameters parameters)
 294                 {
 295                         if (m_disposed)
 296                                 throw new ObjectDisposedException (Locale.GetText ("Keypair was disposed"));
 297
 298                         // if missing "mandatory" parameters
 299                         if (parameters.Exponent == null)
 300                                 throw new CryptographicException (Locale.GetText ("Missing Exponent"));
 301                         if (parameters.Modulus == null)
 302                                 throw new CryptographicException (Locale.GetText ("Missing Modulus"));
 303
 304                         e = new BigInteger (parameters.Exponent);
 305                         n = new BigInteger (parameters.Modulus);
 306                         // only if the private key is present
 307                         if (parameters.D != null)
 308                                 d = new BigInteger (parameters.D);
 309                         if (parameters.DP != null)
 310                                 dp = new BigInteger (parameters.DP);
 311                         if (parameters.DQ != null)
 312                                 dq = new BigInteger (parameters.DQ);
 313                         if (parameters.InverseQ != null)
 314                                 qInv = new BigInteger (parameters.InverseQ);
 315                         if (parameters.P != null)
 316                                 p = new BigInteger (parameters.P);
 317                         if (parameters.Q != null)
 318                                 q = new BigInteger (parameters.Q);
 319
 320                         // we now have a keypair
 321                         keypairGenerated = true;
 322                         bool privateKey = ((p != null) && (q != null) && (dp != null));
 323                         isCRTpossible = (privateKey && (dq != null) && (qInv != null));
 324
 325                         // check if the public/private keys match
 326                         // the way the check is made allows a bad D to work if CRT is available (like MS does, see unit tests)
 327                         if (!privateKey)
 328                                 return;
 329
 330                         // always check n == p * q
 331                         bool ok = (n == (p * q));
 332                         if (ok) {
 333                                 // we now know that p and q are correct, so (p - 1), (q - 1) and phi will be ok too
 334                                 BigInteger pSub1 = (p - 1);
 335                                 BigInteger qSub1 = (q - 1);
 336                                 BigInteger phi = pSub1 * qSub1;
 337                                 // e is fairly static but anyway we can ensure it makes sense by recomputing d
 338                                 BigInteger dcheck = e.ModInverse (phi);
 339
 340                                 // now if our new d(check) is different than the d we're provided then we cannot
 341                                 // be sure if 'd' or 'e' is invalid... (note that, from experience, 'd' is more
 342                                 // likely to be invalid since it's twice as large as DP (or DQ) and sits at the
 343                                 // end of the structure (e.g. truncation).
 344                                 ok = (d == dcheck);
 345
 346                                 // ... unless we have the pre-computed CRT parameters
 347                                 if (!ok && isCRTpossible) {
 348                                         // we can override the previous decision since Mono always prefer, for
 349                                         // performance reasons, using the CRT algorithm
 350                                         ok = (dp == (dcheck % pSub1)) && (dq == (dcheck % qSub1)) &&
 351                                                 (qInv == q.ModInverse (p));
 352                                 }
 353                         }
 354
 355                         if (!ok)
 356                                 throw new CryptographicException (Locale.GetText ("Private/public key mismatch"));
 357                 }
 358
 359                 protected override void Dispose (bool disposing)
 360                 {
 361                         if (!m_disposed) {
 362                                 // Always zeroize private key
 363                                 if (d != null) {
 364                                         d.Clear ();
 365                                         d = null;
 366                                 }
 367                                 if (p != null) {
 368                                         p.Clear ();
 369                                         p = null;
 370                                 }
 371                                 if (q != null) {
 372                                         q.Clear ();
 373                                         q = null;
 374                                 }
 375                                 if (dp != null) {
 376                                         dp.Clear ();
 377                                         dp = null;
 378                                 }
 379                                 if (dq != null) {
 380                                         dq.Clear ();
 381                                         dq = null;
 382                                 }
 383                                 if (qInv != null) {
 384                                         qInv.Clear ();
 385                                         qInv = null;
 386                                 }
 387
 388                                 if (disposing) {
 389                                         // clear public key
 390                                         if (e != null) {
 391                                                 e.Clear ();
 392                                                 e = null;
 393                                         }
 394                                         if (n != null) {
 395                                                 n.Clear ();
 396                                                 n = null;
 397                                         }
 398                                 }
 399                         }
 400                         // call base class
 401                         // no need as they all are abstract before us
 402                         m_disposed = true;
 403                 }
 404
 405                 public delegate void KeyGeneratedEventHandler (object sender, EventArgs e);
 406
 407                 public event KeyGeneratedEventHandler KeyGenerated;
 408
 409                 public override string ToXmlString (bool includePrivateParameters)
 410                 {
 411                         StringBuilder sb = new StringBuilder ();
 412                         RSAParameters rsaParams = ExportParameters (includePrivateParameters);
 413                         try {
 414                                 sb.Append ("<RSAKeyValue>");
 415
 416                                 sb.Append ("<Modulus>");
 417                                 sb.Append (Convert.ToBase64String (rsaParams.Modulus));
 418                                 sb.Append ("</Modulus>");
 419
 420                                 sb.Append ("<Exponent>");
 421                                 sb.Append (Convert.ToBase64String (rsaParams.Exponent));
 422                                 sb.Append ("</Exponent>");
 423
 424                                 if (includePrivateParameters) {
 425                                         if (rsaParams.P != null) {
 426                                                 sb.Append ("<P>");
 427                                                 sb.Append (Convert.ToBase64String (rsaParams.P));
 428                                                 sb.Append ("</P>");
 429                                         }
 430                                         if (rsaParams.Q != null) {
 431                                                 sb.Append ("<Q>");
 432                                                 sb.Append (Convert.ToBase64String (rsaParams.Q));
 433                                                 sb.Append ("</Q>");
 434                                         }
 435                                         if (rsaParams.DP != null) {
 436                                                 sb.Append ("<DP>");
 437                                                 sb.Append (Convert.ToBase64String (rsaParams.DP));
 438                                                 sb.Append ("</DP>");
 439                                         }
 440                                         if (rsaParams.DQ != null) {
 441                                                 sb.Append ("<DQ>");
 442                                                 sb.Append (Convert.ToBase64String (rsaParams.DQ));
 443                                                 sb.Append ("</DQ>");
 444                                         }
 445                                         if (rsaParams.InverseQ != null) {
 446                                                 sb.Append ("<InverseQ>");
 447                                                 sb.Append (Convert.ToBase64String (rsaParams.InverseQ));
 448                                                 sb.Append ("</InverseQ>");
 449                                         }
 450                                         sb.Append ("<D>");
 451                                         sb.Append (Convert.ToBase64String (rsaParams.D));
 452                                         sb.Append ("</D>");
 453                                 }
 454
 455                                 sb.Append ("</RSAKeyValue>");
 456                         }
 457                         catch {
 458                                 if (rsaParams.P != null)
 459                                         Array.Clear (rsaParams.P, 0, rsaParams.P.Length);
 460                                 if (rsaParams.Q != null)
 461                                         Array.Clear (rsaParams.Q, 0, rsaParams.Q.Length);
 462                                 if (rsaParams.DP != null)
 463                                         Array.Clear (rsaParams.DP, 0, rsaParams.DP.Length);
 464                                 if (rsaParams.DQ != null)
 465                                         Array.Clear (rsaParams.DQ, 0, rsaParams.DQ.Length);
 466                                 if (rsaParams.InverseQ != null)
 467                                         Array.Clear (rsaParams.InverseQ, 0, rsaParams.InverseQ.Length);
 468                                 if (rsaParams.D != null)
 469                                         Array.Clear (rsaParams.D, 0, rsaParams.D.Length);
 470                                 throw;
 471                         }
 472
 473                         return sb.ToString ();
 474                 }
 475
 476                 // internal for Mono 1.0.x in order to preserve public contract
 477                 // they are public for Mono 1.1.x (for 1.2) as the API isn't froze ATM
 478
 479                 public bool UseKeyBlinding {
 480                         get { return keyBlinding; }
 481                         // you REALLY shoudn't touch this (true is fine ;-)
 482                         set { keyBlinding = value; }
 483                 }
 484
 485                 public bool IsCrtPossible {
 486                         // either the key pair isn't generated (and will be
 487                         // generated with CRT parameters) or CRT is (or isn't)
 488                         // possible (in case the key was imported)
 489                         get { return (!keypairGenerated || isCRTpossible); }
 490                 }
 491
 492                 private byte[] GetPaddedValue (BigInteger value, int length)
 493                 {
 494                         byte[] result = value.GetBytes ();
 495                         if (result.Length >= length)
 496                                 return result;
 497
 498                         // left-pad 0x00 value on the result (same integer, correct length)
 499                         byte[] padded = new byte[length];
 500                         Buffer.BlockCopy (result, 0, padded, (length - result.Length), result.Length);
 501                         // temporary result may contain decrypted (plaintext) data, clear it
 502                         Array.Clear (result, 0, result.Length);
 503                         return padded;
 504                 }
 505         }
 506 }