pd.if.org Git - zpackage/blob - 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  *
   6  * The library is free for all purposes without any express
   7  * guarantee it works.
   8  */
   9 #include "tomcrypt.h"
  10
  11 /**
  12   @file base64_decode.c
  13   Compliant base64 code donated by Wayne Scott (wscott@bitmover.com)
  14   base64 URL Safe variant (RFC 4648 section 5) by Karel Miko
  15 */
  16
  17
  18 #if defined(LTC_BASE64) || defined (LTC_BASE64_URL)
  19
  20 #if defined(LTC_BASE64)
  21 static const unsigned char map_base64[256] = {
  22 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  23 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  24 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  25 255, 255, 255, 255, 255, 255, 255,  62, 255, 255, 255,  63,
  26  52,  53,  54,  55,  56,  57,  58,  59,  60,  61, 255, 255,
  27 255, 254, 255, 255, 255,   0,   1,   2,   3,   4,   5,   6,
  28   7,   8,   9,  10,  11,  12,  13,  14,  15,  16,  17,  18,
  29  19,  20,  21,  22,  23,  24,  25, 255, 255, 255, 255, 255,
  30 255,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,
  31  37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48,
  32  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,
  42 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  43 255, 255, 255, 255 };
  44 #endif /* LTC_BASE64 */
  45
  46 static const unsigned char map_base64url[] = {
  47 #if defined(LTC_BASE64_URL)
  48 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  49 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  50 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  51 255, 255, 255, 255, 255, 255, 255, 255, 255,  62, 255, 255,
  52  52,  53,  54,  55,  56,  57,  58,  59,  60,  61, 255, 255,
  53 255, 254, 255, 255, 255,   0,   1,   2,   3,   4,   5,   6,
  54   7,   8,   9,  10,  11,  12,  13,  14,  15,  16,  17,  18,
  55  19,  20,  21,  22,  23,  24,  25, 255, 255, 255, 255,  63,
  56 255,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,
  57  37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48,
  58  49,  50,  51, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  59 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  60 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  61 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  62 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  63 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  64 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  65 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  66 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  67 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  68 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  69 255, 255, 255, 255
  70 #endif /* LTC_BASE64_URL */
  71 };
  72
  73 enum {
  74    relaxed = 0,
  75    strict = 1
  76 };
  77
  78 static int _base64_decode_internal(const unsigned char *in,  unsigned long inlen,
  79                                  unsigned char *out, unsigned long *outlen,
  80                            const unsigned char *map, int is_strict)
  81 {
  82    unsigned long t, x, y, z;
  83    unsigned char c;
  84    int           g;
  85
  86    LTC_ARGCHK(in     != NULL);
  87    LTC_ARGCHK(out    != NULL);
  88    LTC_ARGCHK(outlen != NULL);
  89
  90    g = 0; /* '=' counter */
  91    for (x = y = z = t = 0; x < inlen; x++) {
  92        c = map[in[x]&0xFF];
  93        if (c == 254) {
  94           g++;
  95           continue;
  96        }
  97        else if (is_strict && g > 0) {
  98           /* we only allow '=' to be at the end */
  99           return CRYPT_INVALID_PACKET;
 100        }
 101        if (c == 255) {
 102           if (is_strict)
 103              return CRYPT_INVALID_PACKET;
 104           else
 105              continue;
 106        }
 107
 108        t = (t<<6)|c;
 109
 110        if (++y == 4) {
 111           if (z + 3 > *outlen) return CRYPT_BUFFER_OVERFLOW;
 112           out[z++] = (unsigned char)((t>>16)&255);
 113           out[z++] = (unsigned char)((t>>8)&255);
 114           out[z++] = (unsigned char)(t&255);
 115           y = t = 0;
 116        }
 117    }
 118
 119    if (y != 0) {
 120       if (y == 1) return CRYPT_INVALID_PACKET;
 121       if ((y + g) != 4 && is_strict && map != map_base64url) return CRYPT_INVALID_PACKET;
 122       t = t << (6 * (4 - y));
 123       if (z + y - 1 > *outlen) return CRYPT_BUFFER_OVERFLOW;
 124       if (y >= 2) out[z++] = (unsigned char) ((t >> 16) & 255);
 125       if (y == 3) out[z++] = (unsigned char) ((t >> 8) & 255);
 126    }
 127    *outlen = z;
 128    return CRYPT_OK;
 129 }
 130
 131 #if defined(LTC_BASE64)
 132 /**
 133    Relaxed base64 decode a block of memory
 134    @param in       The base64 data to decode
 135    @param inlen    The length of the base64 data
 136    @param out      [out] The destination of the binary decoded data
 137    @param outlen   [in/out] The max size and resulting size of the decoded data
 138    @return CRYPT_OK if successful
 139 */
 140 int base64_decode(const unsigned char *in,  unsigned long inlen,
 141                         unsigned char *out, unsigned long *outlen)
 142 {
 143     return _base64_decode_internal(in, inlen, out, outlen, map_base64, relaxed);
 144 }
 145
 146 /**
 147    Strict base64 decode a block of memory
 148    @param in       The base64 data to decode
 149    @param inlen    The length of the base64 data
 150    @param out      [out] The destination of the binary decoded data
 151    @param outlen   [in/out] The max size and resulting size of the decoded data
 152    @return CRYPT_OK if successful
 153 */
 154 int base64_strict_decode(const unsigned char *in,  unsigned long inlen,
 155                         unsigned char *out, unsigned long *outlen)
 156 {
 157    return _base64_decode_internal(in, inlen, out, outlen, map_base64, strict);
 158 }
 159 #endif /* LTC_BASE64 */
 160
 161 #if defined(LTC_BASE64_URL)
 162 /**
 163    Relaxed base64 (URL Safe, RFC 4648 section 5) decode a block of memory
 164    @param in       The base64 data to decode
 165    @param inlen    The length of the base64 data
 166    @param out      [out] The destination of the binary decoded data
 167    @param outlen   [in/out] The max size and resulting size of the decoded data
 168    @return CRYPT_OK if successful
 169 */
 170 int base64url_decode(const unsigned char *in,  unsigned long inlen,
 171                            unsigned char *out, unsigned long *outlen)
 172 {
 173     return _base64_decode_internal(in, inlen, out, outlen, map_base64url, relaxed);
 174 }
 175
 176 /**
 177    Strict base64 (URL Safe, RFC 4648 section 5) decode a block of memory
 178    @param in       The base64 data to decode
 179    @param inlen    The length of the base64 data
 180    @param out      [out] The destination of the binary decoded data
 181    @param outlen   [in/out] The max size and resulting size of the decoded data
 182    @return CRYPT_OK if successful
 183 */
 184 int base64url_strict_decode(const unsigned char *in,  unsigned long inlen,
 185                            unsigned char *out, unsigned long *outlen)
 186 {
 187     return _base64_decode_internal(in, inlen, out, outlen, map_base64url, strict);
 188 }
 189 #endif /* LTC_BASE64_URL */
 190
 191 #endif
 192
 193
 194 /* ref:         $Format:%D$ */
 195 /* git commit:  $Format:%H$ */
 196 /* commit time: $Format:%ai$ */