1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis */
2 /* SPDX-License-Identifier: Unlicense */
3 #include "tomcrypt_private.h"
4
5 /**
6 @file base64_decode.c
7 Compliant base64 code donated by Wayne Scott (wscott@bitmover.com)
8 base64 URL Safe variant (RFC 4648 section 5) by Karel Miko
9 */
10
11
12 #if defined(LTC_BASE64) || defined (LTC_BASE64_URL)
13
14 /* 253 - ignored in "relaxed" + "insane" mode: TAB(9), CR(13), LF(10), space(32)
15 * 254 - padding character '=' (allowed only at the end)
16 * 255 - ignored in "insane" mode, but not allowed in "relaxed" + "strict" mode
17 */
18
19 #if defined(LTC_BASE64)
20 static const unsigned char map_base64[256] = {
21 255, 255, 255, 255, 255, 255, 255, 255, 255, 253, 253, 255,
22 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
23 255, 255, 255, 255, 255, 255, 255, 255, 253, 255, 255, 255,
24 255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63,
25 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255,
26 255, 254, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6,
27 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
28 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255,
29 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
30 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
31 49, 50, 51, 255, 255, 255, 255, 255, 255, 255, 255, 255,
32 255, 255, 255, 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 };
43 #endif /* LTC_BASE64 */
44
45 static const unsigned char map_base64url[] = {
46 #if defined(LTC_BASE64_URL)
47 255, 255, 255, 255, 255, 255, 255, 255, 255, 253, 253, 255,
48 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
49 255, 255, 255, 255, 255, 255, 255, 255, 253, 255, 255, 255,
50 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 255,
51 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255,
52 255, 254, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6,
53 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
54 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 63,
55 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
56 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
57 49, 50, 51, 255, 255, 255, 255, 255, 255, 255, 255, 255,
58 255, 255, 255, 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
69 #endif /* LTC_BASE64_URL */
70 };
71
72 enum {
73 insane = 0,
74 strict = 1,
75 relaxed = 2
76 };
77
s_base64_decode_internal(const char * in,unsigned long inlen,unsigned char * out,unsigned long * outlen,const unsigned char * map,int mode)78 static int s_base64_decode_internal(const char *in, unsigned long inlen,
79 unsigned char *out, unsigned long *outlen,
80 const unsigned char *map, int mode)
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 if ((in[x] == 0) && (x == (inlen - 1)) && (mode != strict)) {
93 continue; /* allow the last byte to be NUL (relaxed+insane) */
94 }
95 c = map[(unsigned char)in[x]&0xFF];
96 if (c == 254) {
97 g++;
98 continue;
99 }
100 if (c == 253) {
101 if (mode == strict) {
102 return CRYPT_INVALID_PACKET;
103 }
104 continue; /* allow to ignore white-spaces (relaxed+insane) */
105 }
106 if (c == 255) {
107 if (mode == insane) {
108 continue; /* allow to ignore invalid garbage (insane) */
109 }
110 return CRYPT_INVALID_PACKET;
111 }
112 if ((g > 0) && (mode != insane)) {
113 /* we only allow '=' to be at the end (strict+relaxed) */
114 return CRYPT_INVALID_PACKET;
115 }
116
117 t = (t<<6)|c;
118
119 if (++y == 4) {
120 if (z + 3 > *outlen) return CRYPT_BUFFER_OVERFLOW;
121 out[z++] = (unsigned char)((t>>16)&255);
122 out[z++] = (unsigned char)((t>>8)&255);
123 out[z++] = (unsigned char)(t&255);
124 y = t = 0;
125 }
126 }
127
128 if (y != 0) {
129 if (y == 1) return CRYPT_INVALID_PACKET;
130 if (((y + g) != 4) && (mode == strict) && (map != map_base64url)) return CRYPT_INVALID_PACKET;
131 t = t << (6 * (4 - y));
132 if (z + y - 1 > *outlen) return CRYPT_BUFFER_OVERFLOW;
133 if (y >= 2) out[z++] = (unsigned char) ((t >> 16) & 255);
134 if (y == 3) out[z++] = (unsigned char) ((t >> 8) & 255);
135 }
136 *outlen = z;
137 return CRYPT_OK;
138 }
139
140 #if defined(LTC_BASE64)
141 /**
142 Dangerously relaxed base64 decode a block of memory
143 @param in The base64 data to decode
144 @param inlen The length of the base64 data
145 @param out [out] The destination of the binary decoded data
146 @param outlen [in/out] The max size and resulting size of the decoded data
147 @return CRYPT_OK if successful
148 */
base64_decode(const char * in,unsigned long inlen,unsigned char * out,unsigned long * outlen)149 int base64_decode(const char *in, unsigned long inlen,
150 unsigned char *out, unsigned long *outlen)
151 {
152 return s_base64_decode_internal(in, inlen, out, outlen, map_base64, insane);
153 }
154
155 /**
156 Strict base64 decode a block of memory
157 @param in The base64 data to decode
158 @param inlen The length of the base64 data
159 @param out [out] The destination of the binary decoded data
160 @param outlen [in/out] The max size and resulting size of the decoded data
161 @return CRYPT_OK if successful
162 */
base64_strict_decode(const char * in,unsigned long inlen,unsigned char * out,unsigned long * outlen)163 int base64_strict_decode(const char *in, unsigned long inlen,
164 unsigned char *out, unsigned long *outlen)
165 {
166 return s_base64_decode_internal(in, inlen, out, outlen, map_base64, strict);
167 }
168
169 /**
170 Sane base64 decode a block of memory
171 @param in The base64 data to decode
172 @param inlen The length of the base64 data
173 @param out [out] The destination of the binary decoded data
174 @param outlen [in/out] The max size and resulting size of the decoded data
175 @return CRYPT_OK if successful
176 */
base64_sane_decode(const char * in,unsigned long inlen,unsigned char * out,unsigned long * outlen)177 int base64_sane_decode(const char *in, unsigned long inlen,
178 unsigned char *out, unsigned long *outlen)
179 {
180 return s_base64_decode_internal(in, inlen, out, outlen, map_base64, relaxed);
181 }
182 #endif /* LTC_BASE64 */
183
184 #if defined(LTC_BASE64_URL)
185 /**
186 Dangerously relaxed base64 (URL Safe, RFC 4648 section 5) decode a block of memory
187 @param in The base64 data to decode
188 @param inlen The length of the base64 data
189 @param out [out] The destination of the binary decoded data
190 @param outlen [in/out] The max size and resulting size of the decoded data
191 @return CRYPT_OK if successful
192 */
base64url_decode(const char * in,unsigned long inlen,unsigned char * out,unsigned long * outlen)193 int base64url_decode(const char *in, unsigned long inlen,
194 unsigned char *out, unsigned long *outlen)
195 {
196 return s_base64_decode_internal(in, inlen, out, outlen, map_base64url, insane);
197 }
198
199 /**
200 Strict base64 (URL Safe, RFC 4648 section 5) decode a block of memory
201 @param in The base64 data to decode
202 @param inlen The length of the base64 data
203 @param out [out] The destination of the binary decoded data
204 @param outlen [in/out] The max size and resulting size of the decoded data
205 @return CRYPT_OK if successful
206 */
base64url_strict_decode(const char * in,unsigned long inlen,unsigned char * out,unsigned long * outlen)207 int base64url_strict_decode(const char *in, unsigned long inlen,
208 unsigned char *out, unsigned long *outlen)
209 {
210 return s_base64_decode_internal(in, inlen, out, outlen, map_base64url, strict);
211 }
212
213 /**
214 Sane base64 (URL Safe, RFC 4648 section 5) decode a block of memory
215 @param in The base64 data to decode
216 @param inlen The length of the base64 data
217 @param out [out] The destination of the binary decoded data
218 @param outlen [in/out] The max size and resulting size of the decoded data
219 @return CRYPT_OK if successful
220 */
base64url_sane_decode(const char * in,unsigned long inlen,unsigned char * out,unsigned long * outlen)221 int base64url_sane_decode(const char *in, unsigned long inlen,
222 unsigned char *out, unsigned long *outlen)
223 {
224 return s_base64_decode_internal(in, inlen, out, outlen, map_base64url, relaxed);
225 }
226 #endif /* LTC_BASE64_URL */
227
228 #endif
229
230