lib/auth_srp_sb64.c

   1 /*
   2  * Copyright (C) 2001, 2002, 2003, 2004, 2005, 2008, 2010 Free Software
   3  * Foundation, Inc.
   4  *
   5  * Author: Nikos Mavrogiannopoulos
   6  *
   7  * This file is part of GNUTLS.
   8  *
   9  * The GNUTLS library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public License
  11  * as published by the Free Software Foundation; either version 2.1 of
  12  * the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful, but
  15  * WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  22  * USA
  23  *
  24  */
  25
  26 #include <gnutls_int.h>
  27 #include <gnutls_errors.h>
  28 #include <gnutls_datum.h>
  29 #include <auth_srp_passwd.h>
  30
  31 #ifdef ENABLE_SRP
  32
  33 /* this a modified base64 for srp !!!
  34  * It seems that everybody makes an own base64 conversion.
  35  */
  36 static const uint8_t b64table[] =
  37   "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";
  38
  39 static const uint8_t asciitable[128] = {
  40   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  41   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  42   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  43   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  44   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  45   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  46   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  47   0xff, 0xff, 0xff, 0xff, 0x3e, 0x3f,
  48   0x00, 0x01, 0x02, 0x03, 0x04, 0x05,
  49   0x06, 0x07, 0x08, 0x09, 0xff, 0xff,
  50   0xff, 0xff, 0xff, 0xff, 0xff, 0x0a,
  51   0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10,
  52   0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
  53   0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c,
  54   0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22,
  55   0x23, 0xff, 0xff, 0xff, 0xff, 0xff,
  56   0xff, 0x24, 0x25, 0x26, 0x27, 0x28,
  57   0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e,
  58   0x2f, 0x30, 0x31, 0x32, 0x33, 0x34,
  59   0x35, 0x36, 0x37, 0x38, 0x39, 0x3a,
  60   0x3b, 0x3c, 0x3d, 0xff, 0xff, 0xff,
  61   0xff, 0xff
  62 };
  63
  64 inline static int
  65 encode (uint8_t * result, const uint8_t * rdata, int left)
  66 {
  67
  68   int data_len;
  69   int c, ret = 4;
  70   uint8_t data[3];
  71
  72   if (left > 3)
  73     data_len = 3;
  74   else
  75     data_len = left;
  76
  77   data[0] = data[1] = data[2] = 0;
  78   memcpy (data, rdata, data_len);
  79
  80   switch (data_len)
  81     {
  82     case 3:
  83       result[0] = b64table[((data[0] & 0xfc) >> 2)];
  84       result[1] =
  85         b64table[(((((data[0] & 0x03) & 0xff) << 4) & 0xff) |
  86                   ((data[1] & 0xf0) >> 4))];
  87       result[2] =
  88         b64table[((((data[1] & 0x0f) << 2) & 0xff) |
  89                   ((data[2] & 0xc0) >> 6))];
  90       result[3] = b64table[(data[2] & 0x3f) & 0xff];
  91       break;
  92     case 2:
  93       if ((c = ((data[0] & 0xf0) >> 4)) != 0)
  94         {
  95           result[0] = b64table[c];
  96           result[1] =
  97             b64table[((((data[0] & 0x0f) << 2) & 0xff) |
  98                       ((data[1] & 0xc0) >> 6))];
  99           result[2] = b64table[(data[1] & 0x3f) & 0xff];
 100           result[3] = '\0';
 101           ret -= 1;
 102         }
 103       else
 104         {
 105           if ((c = ((data[0] & 0x0f) << 2) | ((data[1] & 0xc0) >> 6)) != 0)
 106             {
 107               result[0] = b64table[c];
 108               result[1] = b64table[data[1] & 0x3f];
 109               result[2] = '\0';
 110               result[3] = '\0';
 111               ret -= 2;
 112             }
 113           else
 114             {
 115               result[0] = b64table[data[0] & 0x3f];
 116               result[1] = '\0';
 117               result[2] = '\0';
 118               result[3] = '\0';
 119               ret -= 3;
 120             }
 121         }
 122       break;
 123     case 1:
 124       if ((c = ((data[0] & 0xc0) >> 6)) != 0)
 125         {
 126           result[0] = b64table[c];
 127           result[1] = b64table[(data[0] & 0x3f) & 0xff];
 128           result[2] = '\0';
 129           result[3] = '\0';
 130           ret -= 2;
 131         }
 132       else
 133         {
 134           result[0] = b64table[(data[0] & 0x3f) & 0xff];
 135           result[1] = '\0';
 136           result[2] = '\0';
 137           result[3] = '\0';
 138           ret -= 3;
 139         }
 140       break;
 141     default:
 142       return -1;
 143     }
 144
 145   return ret;
 146
 147 }
 148
 149 /* encodes data and puts the result into result (locally allocated)
 150  * The result_size is the return value
 151  */
 152 static int
 153 _gnutls_sbase64_encode (uint8_t * data, size_t data_size, uint8_t ** result)
 154 {
 155   unsigned i, j;
 156   int ret, tmp;
 157   opaque tmpres[4];
 158   int mod = data_size % 3;
 159
 160   ret = mod;
 161   if (ret != 0)
 162     ret = 4;
 163   else
 164     ret = 0;
 165
 166   ret += (data_size * 4) / 3;
 167
 168   (*result) = gnutls_calloc (1, ret + 1);
 169   if ((*result) == NULL)
 170     return -1;
 171
 172   i = j = 0;
 173 /* encode the bytes that are not a multiple of 3
 174  */
 175   if (mod > 0)
 176     {
 177       tmp = encode (tmpres, &data[0], mod);
 178       if (tmp < 0)
 179         {
 180           gnutls_free ((*result));
 181           return tmp;
 182         }
 183
 184       memcpy (&(*result)[0], tmpres, tmp);
 185       i = mod;
 186       j = tmp;
 187
 188     }
 189 /* encode the rest
 190  */
 191   for (; i < data_size; i += 3, j += 4)
 192     {
 193       tmp = encode (tmpres, &data[i], data_size - i);
 194       if (tmp < 0)
 195         {
 196           gnutls_free ((*result));
 197           return tmp;
 198         }
 199       memcpy (&(*result)[j], tmpres, tmp);
 200     }
 201
 202   return strlen (*result);
 203 }
 204
 205
 206 /* data must be 4 bytes
 207  * result should be 3 bytes
 208  */
 209 #define TOASCII(c) (c < 127 ? asciitable[c] : 0xff)
 210 inline static int
 211 decode (uint8_t * result, const uint8_t * data)
 212 {
 213   uint8_t a1, a2;
 214   int ret = 3;
 215
 216   memset (result, 0, 3);
 217
 218   a1 = TOASCII (data[3]);
 219   a2 = TOASCII (data[2]);
 220   if (a1 != 0xff)
 221     result[2] = a1 & 0xff;
 222   else
 223     return -1;
 224   if (a2 != 0xff)
 225     result[2] |= ((a2 & 0x03) << 6) & 0xff;
 226
 227   a1 = a2;
 228   a2 = TOASCII (data[1]);
 229   if (a1 != 0xff)
 230     result[1] = ((a1 & 0x3c) >> 2);
 231   if (a2 != 0xff)
 232     result[1] |= ((a2 & 0x0f) << 4);
 233   else if (a1 == 0xff || result[1] == 0)
 234     ret--;
 235
 236   a1 = a2;
 237   a2 = TOASCII (data[0]);
 238   if (a1 != 0xff)
 239     result[0] = (((a1 & 0x30) >> 4) & 0xff);
 240   if (a2 != 0xff)
 241     result[0] |= ((a2 << 2) & 0xff);
 242   else if (a1 == 0xff || result[0] == 0)
 243     ret--;
 244
 245   return ret;
 246 }
 247
 248 /* decodes data and puts the result into result (locally allocated)
 249  * The result_size is the return value.
 250  * That function does not ignore newlines tabs etc. You should remove them
 251  * before calling it.
 252  */
 253 int
 254 _gnutls_sbase64_decode (uint8_t * data, size_t idata_size, uint8_t ** result)
 255 {
 256   unsigned i, j;
 257   int ret, left;
 258   int data_size, tmp;
 259   uint8_t datrev[4];
 260   uint8_t tmpres[3];
 261
 262   data_size = (idata_size / 4) * 4;
 263   left = idata_size % 4;
 264
 265   ret = (data_size / 4) * 3;
 266
 267   if (left > 0)
 268     ret += 3;
 269
 270   (*result) = gnutls_malloc (ret + 1);
 271   if ((*result) == NULL)
 272     return -1;
 273
 274   /* the first "block" is treated with special care */
 275   tmp = 0;
 276   if (left > 0)
 277     {
 278       memset (datrev, 0, 4);
 279       memcpy (&datrev[4 - left], data, left);
 280
 281       tmp = decode (tmpres, datrev);
 282       if (tmp < 0)
 283         {
 284           gnutls_free ((*result));
 285           *result = NULL;
 286           return tmp;
 287         }
 288
 289       memcpy (*result, &tmpres[3 - tmp], tmp);
 290       if (tmp < 3)
 291         ret -= (3 - tmp);
 292     }
 293
 294   /* rest data */
 295   for (i = left, j = tmp; i < idata_size; i += 4)
 296     {
 297       tmp = decode (tmpres, &data[i]);
 298       if (tmp < 0)
 299         {
 300           gnutls_free ((*result));
 301           *result = NULL;
 302           return tmp;
 303         }
 304       memcpy (&(*result)[j], tmpres, tmp);
 305       if (tmp < 3)
 306         ret -= (3 - tmp);
 307       j += 3;
 308     }
 309
 310   return ret;
 311 }
 312
 313 /**
 314   * gnutls_srp_base64_encode - Encode raw data using SRP-Base64
 315   * @data: contain the raw data
 316   * @result: the place where base64 data will be copied
 317   * @result_size: holds the size of the result
 318   *
 319   * This function will convert the given data to printable data, using
 320   * the base64 encoding, as used in the libsrp.  This is the encoding
 321   * used in SRP password files.  If the provided buffer is not long
 322   * enough GNUTLS_E_SHORT_MEMORY_BUFFER is returned.
 323   *
 324   * Warning!  This base64 encoding is not the "standard" encoding, so
 325   * do not use it for non-SRP purposes.
 326   *
 327   * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not
 328   * long enough, or 0 on success.
 329   **/
 330 int
 331 gnutls_srp_base64_encode (const gnutls_datum_t * data, char *result,
 332                           size_t * result_size)
 333 {
 334   opaque *ret;
 335   int size;
 336
 337   size = _gnutls_sbase64_encode (data->data, data->size, &ret);
 338   if (size < 0)
 339     return size;
 340
 341   if (result == NULL || *result_size < (size_t) size)
 342     {
 343       gnutls_free (ret);
 344       *result_size = size;
 345       return GNUTLS_E_SHORT_MEMORY_BUFFER;
 346     }
 347   else
 348     {
 349       memcpy (result, ret, size);
 350       gnutls_free (ret);
 351       *result_size = size;
 352     }
 353
 354   return 0;
 355 }
 356
 357 /**
 358   * gnutls_srp_base64_encode_alloc - encode raw data using SRP-Base64
 359   * @data: contains the raw data
 360   * @result: will hold the newly allocated encoded data
 361   *
 362   * This function will convert the given data to printable data, using
 363   * the base64 encoding.  This is the encoding used in SRP password
 364   * files.  This function will allocate the required memory to hold
 365   * the encoded data.
 366   *
 367   * You should use gnutls_free() to free the returned data.
 368   *
 369   * Warning!  This base64 encoding is not the "standard" encoding, so
 370   * do not use it for non-SRP purposes.
 371   *
 372   * Returns: 0 on success, or an error code.
 373   **/
 374 int
 375 gnutls_srp_base64_encode_alloc (const gnutls_datum_t * data,
 376                                 gnutls_datum_t * result)
 377 {
 378   opaque *ret;
 379   int size;
 380
 381   size = _gnutls_sbase64_encode (data->data, data->size, &ret);
 382   if (size < 0)
 383     return size;
 384
 385   if (result == NULL)
 386     {
 387       gnutls_free (ret);
 388       return GNUTLS_E_INVALID_REQUEST;
 389     }
 390   else
 391     {
 392       result->data = ret;
 393       result->size = size;
 394     }
 395
 396   return 0;
 397 }
 398
 399 /**
 400   * gnutls_srp_base64_decode - decode SRP-base64 encoded data
 401   * @b64_data: contain the encoded data
 402   * @result: the place where decoded data will be copied
 403   * @result_size: holds the size of the result
 404   *
 405   * This function will decode the given encoded data, using the base64
 406   * encoding found in libsrp.
 407   *
 408   * Note that b64_data should be null terminated.
 409   *
 410   * Warning!  This base64 encoding is not the "standard" encoding, so
 411   * do not use it for non-SRP purposes.
 412   *
 413   * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not
 414   * long enough, or 0 on success.
 415   **/
 416 int
 417 gnutls_srp_base64_decode (const gnutls_datum_t * b64_data, char *result,
 418                           size_t * result_size)
 419 {
 420   opaque *ret;
 421   int size;
 422
 423   size = _gnutls_sbase64_decode (b64_data->data, b64_data->size, &ret);
 424   if (size < 0)
 425     return size;
 426
 427   if (result == NULL || *result_size < (size_t) size)
 428     {
 429       gnutls_free (ret);
 430       *result_size = size;
 431       return GNUTLS_E_SHORT_MEMORY_BUFFER;
 432     }
 433   else
 434     {
 435       memcpy (result, ret, size);
 436       gnutls_free (ret);
 437       *result_size = size;
 438     }
 439
 440   return 0;
 441 }
 442
 443 /**
 444   * gnutls_srp_base64_decode_alloc - decode SRP-base64 encoded data
 445   * @b64_data: contains the encoded data
 446   * @result: the place where decoded data lie
 447   *
 448   * This function will decode the given encoded data. The decoded data
 449   * will be allocated, and stored into result.  It will decode using
 450   * the base64 algorithm as used in libsrp.
 451   *
 452   * You should use gnutls_free() to free the returned data.
 453   *
 454   * Warning!  This base64 encoding is not the "standard" encoding, so
 455   * do not use it for non-SRP purposes.
 456   *
 457   * Returns: 0 on success, or an error code.
 458   **/
 459 int
 460 gnutls_srp_base64_decode_alloc (const gnutls_datum_t * b64_data,
 461                                 gnutls_datum_t * result)
 462 {
 463   opaque *ret;
 464   int size;
 465
 466   size = _gnutls_sbase64_decode (b64_data->data, b64_data->size, &ret);
 467   if (size < 0)
 468     return size;
 469
 470   if (result == NULL)
 471     {
 472       gnutls_free (ret);
 473       return GNUTLS_E_INVALID_REQUEST;
 474     }
 475   else
 476     {
 477       result->data = ret;
 478       result->size = size;
 479     }
 480
 481   return 0;
 482 }
 483
 484 #endif /* ENABLE_SRP */