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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: $Format:%ai$ */