lib/auth/srp_sb64.c

   1 /*
   2  * Copyright (C) 2001-2012 Free Software Foundation, Inc.
   3  *
   4  * Author: Nikos Mavrogiannopoulos
   5  *
   6  * This file is part of GnuTLS.
   7  *
   8  * The GnuTLS is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public License
  10  * as published by the Free Software Foundation; either version 3 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program.  If not, see <http://www.gnu.org/licenses/>
  20  *
  21  */
  22
  23 #include <gnutls_int.h>
  24 #include <gnutls_errors.h>
  25 #include <gnutls_datum.h>
  26 #include <auth/srp_passwd.h>
  27
  28 #ifdef ENABLE_SRP
  29
  30 /* this is a modified base64 for srp !!!
  31  * It seems that everybody makes their own base64 conversion.
  32  */
  33 static const uint8_t b64table[] =
  34   "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";
  35
  36 static const uint8_t asciitable[128] = {
  37   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  38   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  39   0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  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, 0x3e, 0x3f,
  45   0x00, 0x01, 0x02, 0x03, 0x04, 0x05,
  46   0x06, 0x07, 0x08, 0x09, 0xff, 0xff,
  47   0xff, 0xff, 0xff, 0xff, 0xff, 0x0a,
  48   0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10,
  49   0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
  50   0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c,
  51   0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22,
  52   0x23, 0xff, 0xff, 0xff, 0xff, 0xff,
  53   0xff, 0x24, 0x25, 0x26, 0x27, 0x28,
  54   0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e,
  55   0x2f, 0x30, 0x31, 0x32, 0x33, 0x34,
  56   0x35, 0x36, 0x37, 0x38, 0x39, 0x3a,
  57   0x3b, 0x3c, 0x3d, 0xff, 0xff, 0xff,
  58   0xff, 0xff
  59 };
  60
  61 inline static int
  62 encode (uint8_t * result, const uint8_t * rdata, int left)
  63 {
  64
  65   int data_len;
  66   int c, ret = 4;
  67   uint8_t data[3];
  68
  69   if (left > 3)
  70     data_len = 3;
  71   else
  72     data_len = left;
  73
  74   data[0] = data[1] = data[2] = 0;
  75   memcpy (data, rdata, data_len);
  76
  77   switch (data_len)
  78     {
  79     case 3:
  80       result[0] = b64table[((data[0] & 0xfc) >> 2)];
  81       result[1] =
  82         b64table[(((((data[0] & 0x03) & 0xff) << 4) & 0xff) |
  83                   ((data[1] & 0xf0) >> 4))];
  84       result[2] =
  85         b64table[((((data[1] & 0x0f) << 2) & 0xff) |
  86                   ((data[2] & 0xc0) >> 6))];
  87       result[3] = b64table[(data[2] & 0x3f) & 0xff];
  88       break;
  89     case 2:
  90       if ((c = ((data[0] & 0xf0) >> 4)) != 0)
  91         {
  92           result[0] = b64table[c];
  93           result[1] =
  94             b64table[((((data[0] & 0x0f) << 2) & 0xff) |
  95                       ((data[1] & 0xc0) >> 6))];
  96           result[2] = b64table[(data[1] & 0x3f) & 0xff];
  97           result[3] = '\0';
  98           ret -= 1;
  99         }
 100       else
 101         {
 102           if ((c = ((data[0] & 0x0f) << 2) | ((data[1] & 0xc0) >> 6)) != 0)
 103             {
 104               result[0] = b64table[c];
 105               result[1] = b64table[data[1] & 0x3f];
 106               result[2] = '\0';
 107               result[3] = '\0';
 108               ret -= 2;
 109             }
 110           else
 111             {
 112               result[0] = b64table[data[0] & 0x3f];
 113               result[1] = '\0';
 114               result[2] = '\0';
 115               result[3] = '\0';
 116               ret -= 3;
 117             }
 118         }
 119       break;
 120     case 1:
 121       if ((c = ((data[0] & 0xc0) >> 6)) != 0)
 122         {
 123           result[0] = b64table[c];
 124           result[1] = b64table[(data[0] & 0x3f) & 0xff];
 125           result[2] = '\0';
 126           result[3] = '\0';
 127           ret -= 2;
 128         }
 129       else
 130         {
 131           result[0] = b64table[(data[0] & 0x3f) & 0xff];
 132           result[1] = '\0';
 133           result[2] = '\0';
 134           result[3] = '\0';
 135           ret -= 3;
 136         }
 137       break;
 138     default:
 139       return -1;
 140     }
 141
 142   return ret;
 143
 144 }
 145
 146 /* encodes data and puts the result into result (locally allocated)
 147  * The result_size is the return value
 148  */
 149 static int
 150 _gnutls_sbase64_encode (uint8_t * data, size_t data_size, char ** result)
 151 {
 152   unsigned i, j;
 153   int ret, tmp;
 154   uint8_t tmpres[4];
 155   int mod = data_size % 3;
 156
 157   ret = mod;
 158   if (ret != 0)
 159     ret = 4;
 160   else
 161     ret = 0;
 162
 163   ret += (data_size * 4) / 3;
 164
 165   (*result) = gnutls_calloc (1, ret + 1);
 166   if ((*result) == NULL)
 167     return -1;
 168
 169   i = j = 0;
 170 /* encode the bytes that are not a multiple of 3
 171  */
 172   if (mod > 0)
 173     {
 174       tmp = encode (tmpres, &data[0], mod);
 175       if (tmp < 0)
 176         {
 177           gnutls_free ((*result));
 178           return tmp;
 179         }
 180
 181       memcpy (&(*result)[0], tmpres, tmp);
 182       i = mod;
 183       j = tmp;
 184
 185     }
 186 /* encode the rest
 187  */
 188   for (; i < data_size; i += 3, j += 4)
 189     {
 190       tmp = encode (tmpres, &data[i], data_size - i);
 191       if (tmp < 0)
 192         {
 193           gnutls_free ((*result));
 194           return tmp;
 195         }
 196       memcpy (&(*result)[j], tmpres, tmp);
 197     }
 198
 199   return strlen (*result);
 200 }
 201
 202
 203 /* data must be 4 bytes
 204  * result should be 3 bytes
 205  */
 206 #define TOASCII(c) (c < 127 ? asciitable[c] : 0xff)
 207 inline static int
 208 decode (uint8_t * result, const uint8_t * data)
 209 {
 210   uint8_t a1, a2;
 211   int ret = 3;
 212
 213   memset (result, 0, 3);
 214
 215   a1 = TOASCII (data[3]);
 216   a2 = TOASCII (data[2]);
 217   if (a1 != 0xff)
 218     result[2] = a1 & 0xff;
 219   else
 220     return -1;
 221   if (a2 != 0xff)
 222     result[2] |= ((a2 & 0x03) << 6) & 0xff;
 223
 224   a1 = a2;
 225   a2 = TOASCII (data[1]);
 226   if (a1 != 0xff)
 227     result[1] = ((a1 & 0x3c) >> 2);
 228   if (a2 != 0xff)
 229     result[1] |= ((a2 & 0x0f) << 4);
 230   else if (a1 == 0xff || result[1] == 0)
 231     ret--;
 232
 233   a1 = a2;
 234   a2 = TOASCII (data[0]);
 235   if (a1 != 0xff)
 236     result[0] = (((a1 & 0x30) >> 4) & 0xff);
 237   if (a2 != 0xff)
 238     result[0] |= ((a2 << 2) & 0xff);
 239   else if (a1 == 0xff || result[0] == 0)
 240     ret--;
 241
 242   return ret;
 243 }
 244
 245 /* decodes data and puts the result into result (locally allocated)
 246  * The result_size is the return value.
 247  * That function does not ignore newlines tabs etc. You should remove them
 248  * before calling it.
 249  */
 250 int
 251 _gnutls_sbase64_decode (char * data, size_t idata_size, uint8_t ** result)
 252 {
 253   unsigned i, j;
 254   int ret, left;
 255   int data_size, tmp;
 256   uint8_t datrev[4];
 257   uint8_t tmpres[3];
 258
 259   data_size = (idata_size / 4) * 4;
 260   left = idata_size % 4;
 261
 262   ret = (data_size / 4) * 3;
 263
 264   if (left > 0)
 265     ret += 3;
 266
 267   (*result) = gnutls_malloc (ret + 1);
 268   if ((*result) == NULL)
 269     return -1;
 270
 271   /* the first "block" is treated with special care */
 272   tmp = 0;
 273   if (left > 0)
 274     {
 275       memset (datrev, 0, 4);
 276       memcpy (&datrev[4 - left], data, left);
 277
 278       tmp = decode (tmpres, datrev);
 279       if (tmp < 0)
 280         {
 281           gnutls_free ((*result));
 282           *result = NULL;
 283           return tmp;
 284         }
 285
 286       memcpy (*result, &tmpres[3 - tmp], tmp);
 287       if (tmp < 3)
 288         ret -= (3 - tmp);
 289     }
 290
 291   /* rest data */
 292   for (i = left, j = tmp; i < idata_size; i += 4)
 293     {
 294       tmp = decode (tmpres, (uint8_t*)&data[i]);
 295       if (tmp < 0)
 296         {
 297           gnutls_free ((*result));
 298           *result = NULL;
 299           return tmp;
 300         }
 301       memcpy (&(*result)[j], tmpres, tmp);
 302       if (tmp < 3)
 303         ret -= (3 - tmp);
 304       j += 3;
 305     }
 306
 307   return ret;
 308 }
 309
 310 /**
 311  * gnutls_srp_base64_encode:
 312  * @data: contain the raw data
 313  * @result: the place where base64 data will be copied
 314  * @result_size: holds the size of the result
 315  *
 316  * This function will convert the given data to printable data, using
 317  * the base64 encoding, as used in the libsrp.  This is the encoding
 318  * used in SRP password files.  If the provided buffer is not long
 319  * enough GNUTLS_E_SHORT_MEMORY_BUFFER is returned.
 320  *
 321  * Warning!  This base64 encoding is not the "standard" encoding, so
 322  * do not use it for non-SRP purposes.
 323  *
 324  * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not
 325  * long enough, or 0 on success.
 326  **/
 327 int
 328 gnutls_srp_base64_encode (const gnutls_datum_t * data, char *result,
 329                           size_t * result_size)
 330 {
 331   char *res;
 332   int size;
 333
 334   size = _gnutls_sbase64_encode (data->data, data->size, &res);
 335   if (size < 0)
 336     return size;
 337
 338   if (result == NULL || *result_size < (size_t) size)
 339     {
 340       gnutls_free (res);
 341       *result_size = size;
 342       return GNUTLS_E_SHORT_MEMORY_BUFFER;
 343     }
 344   else
 345     {
 346       memcpy (result, res, size);
 347       gnutls_free (res);
 348       *result_size = size;
 349     }
 350
 351   return 0;
 352 }
 353
 354 /**
 355  * gnutls_srp_base64_encode_alloc:
 356  * @data: contains the raw data
 357  * @result: will hold the newly allocated encoded data
 358  *
 359  * This function will convert the given data to printable data, using
 360  * the base64 encoding.  This is the encoding used in SRP password
 361  * files.  This function will allocate the required memory to hold
 362  * the encoded data.
 363  *
 364  * You should use gnutls_free() to free the returned data.
 365  *
 366  * Warning!  This base64 encoding is not the "standard" encoding, so
 367  * do not use it for non-SRP purposes.
 368  *
 369  * Returns: 0 on success, or an error code.
 370  **/
 371 int
 372 gnutls_srp_base64_encode_alloc (const gnutls_datum_t * data,
 373                                 gnutls_datum_t * result)
 374 {
 375   char *res;
 376   int size;
 377
 378   size = _gnutls_sbase64_encode (data->data, data->size, &res);
 379   if (size < 0)
 380     return size;
 381
 382   if (result == NULL)
 383     {
 384       gnutls_free (res);
 385       return GNUTLS_E_INVALID_REQUEST;
 386     }
 387   else
 388     {
 389       result->data = (uint8_t*)res;
 390       result->size = size;
 391     }
 392
 393   return 0;
 394 }
 395
 396 /**
 397  * gnutls_srp_base64_decode:
 398  * @b64_data: contain the encoded data
 399  * @result: the place where decoded data will be copied
 400  * @result_size: holds the size of the result
 401  *
 402  * This function will decode the given encoded data, using the base64
 403  * encoding found in libsrp.
 404  *
 405  * Note that @b64_data should be null terminated.
 406  *
 407  * Warning!  This base64 encoding is not the "standard" encoding, so
 408  * do not use it for non-SRP purposes.
 409  *
 410  * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the buffer given is not
 411  * long enough, or 0 on success.
 412  **/
 413 int
 414 gnutls_srp_base64_decode (const gnutls_datum_t * b64_data, char *result,
 415                           size_t * result_size)
 416 {
 417   uint8_t *res;
 418   int size;
 419
 420   size = _gnutls_sbase64_decode ((char*)b64_data->data, b64_data->size, &res);
 421   if (size < 0)
 422     return size;
 423
 424   if (result == NULL || *result_size < (size_t) size)
 425     {
 426       gnutls_free (res);
 427       *result_size = size;
 428       return GNUTLS_E_SHORT_MEMORY_BUFFER;
 429     }
 430   else
 431     {
 432       memcpy (result, res, size);
 433       gnutls_free (res);
 434       *result_size = size;
 435     }
 436
 437   return 0;
 438 }
 439
 440 /**
 441  * gnutls_srp_base64_decode_alloc:
 442  * @b64_data: contains the encoded data
 443  * @result: the place where decoded data lie
 444  *
 445  * This function will decode the given encoded data. The decoded data
 446  * will be allocated, and stored into result.  It will decode using
 447  * the base64 algorithm as used in libsrp.
 448  *
 449  * You should use gnutls_free() to free the returned data.
 450  *
 451  * Warning!  This base64 encoding is not the "standard" encoding, so
 452  * do not use it for non-SRP purposes.
 453  *
 454  * Returns: 0 on success, or an error code.
 455  **/
 456 int
 457 gnutls_srp_base64_decode_alloc (const gnutls_datum_t * b64_data,
 458                                 gnutls_datum_t * result)
 459 {
 460   uint8_t *ret;
 461   int size;
 462
 463   size = _gnutls_sbase64_decode ((char*)b64_data->data, b64_data->size, &ret);
 464   if (size < 0)
 465     return size;
 466
 467   if (result == NULL)
 468     {
 469       gnutls_free (ret);
 470       return GNUTLS_E_INVALID_REQUEST;
 471     }
 472   else
 473     {
 474       result->data = ret;
 475       result->size = size;
 476     }
 477
 478   return 0;
 479 }
 480
 481 #endif /* ENABLE_SRP */