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Viewing changes to libtomcrypt/src/misc/base64/base64_decode.c

  • Committer: Bazaar Package Importer
  • Author(s): Matt Johnston
  • Date: 2005-12-08 19:20:21 UTC
  • mfrom: (1.2.2 upstream)
  • Revision ID: james.westby@ubuntu.com-20051208192021-nyp9rwnt77nsg6ty
Tags: 0.47-1
* New upstream release.
* SECURITY: Fix incorrect buffer sizing.

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libtomcrypt/src/misc/base64/base64_decode.c
 
1
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 
2
 *
 
3
 * LibTomCrypt is a library that provides various cryptographic
 
4
 * algorithms in a highly modular and flexible manner.
 
5
 *
 
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 * The library is free for all purposes without any express
 
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 * guarantee it works.
 
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 *
 
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 * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.org
 
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 */
 
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#include "tomcrypt.h"
 
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/**
 
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  @file base64_decode.c
 
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  Compliant base64 code donated by Wayne Scott (wscott@bitmover.com)
 
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*/
 
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#ifdef BASE64
 
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static const unsigned char map[256] = {
 
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
25
255, 255, 255, 255, 255, 255, 255,  62, 255, 255, 255,  63,
 
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 52,  53,  54,  55,  56,  57,  58,  59,  60,  61, 255, 255,
 
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255, 254, 255, 255, 255,   0,   1,   2,   3,   4,   5,   6,
 
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  7,   8,   9,  10,  11,  12,  13,  14,  15,  16,  17,  18,
 
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 19,  20,  21,  22,  23,  24,  25, 255, 255, 255, 255, 255,
 
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255,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,
 
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 37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48,
 
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 49,  50,  51, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
33
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
34
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
35
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
36
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
37
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
38
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
39
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
40
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
41
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 
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255, 255, 255, 255 };
 
44
 
 
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/**
 
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   base64 decode a block of memory
 
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   @param in       The base64 data to decode
 
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   @param inlen    The length of the base64 data
 
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   @param out      [out] The destination of the binary decoded data
 
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   @param outlen   [in/out] The max size and resulting size of the decoded data
 
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   @return CRYPT_OK if successful
 
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*/
 
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int base64_decode(const unsigned char *in,  unsigned long inlen, 
 
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                        unsigned char *out, unsigned long *outlen)
 
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{
 
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   unsigned long t, x, y, z;
 
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   unsigned char c;
 
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   int           g;
 
59
 
 
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   LTC_ARGCHK(in     != NULL);
 
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   LTC_ARGCHK(out    != NULL);
 
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   LTC_ARGCHK(outlen != NULL);
 
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   g = 3;
 
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   for (x = y = z = t = 0; x < inlen; x++) {
 
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       c = map[in[x]&0xFF];
 
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       if (c == 255) continue;
 
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       /* the final = symbols are read and used to trim the remaining bytes */
 
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       if (c == 254) { 
 
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          c = 0; 
 
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          /* prevent g < 0 which would potentially allow an overflow later */
 
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          if (--g < 0) {
 
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             return CRYPT_INVALID_PACKET;
 
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          }
 
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       } else if (g != 3) {
 
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          /* we only allow = to be at the end */
 
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          return CRYPT_INVALID_PACKET;
 
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       }
 
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       t = (t<<6)|c;
 
81
 
 
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       if (++y == 4) {
 
83
          if (z + g > *outlen) { 
 
84
             return CRYPT_BUFFER_OVERFLOW; 
 
85
          }
 
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          out[z++] = (unsigned char)((t>>16)&255);
 
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          if (g > 1) out[z++] = (unsigned char)((t>>8)&255);
 
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          if (g > 2) out[z++] = (unsigned char)(t&255);
 
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          y = t = 0;
 
90
       }
 
91
   }
 
92
   if (y != 0) {
 
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       return CRYPT_INVALID_PACKET;
 
94
   }
 
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   *outlen = z;
 
96
   return CRYPT_OK;
 
97
}
 
98
 
 
99
#endif
 
100
 
 
101
 
 
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/* $Source: /cvs/libtom/libtomcrypt/src/misc/base64/base64_decode.c,v $ */
 
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/* $Revision: 1.3 $ */
 
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/* $Date: 2005/05/05 14:35:59 $ */