2 * RFC 1521 base64 encoding/decoding
4 * Based on XySSL: Copyright (C) 2006-2008 Christophe Devine
6 * Copyright (C) 2009 Paul Bakker <polarssl_maintainer at polarssl dot org>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License along
19 * with this program; if not, write to the Free Software Foundation, Inc.,
20 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
23 /* $Cambridge: exim/src/src/pdkim/base64.c,v 1.2 2009/06/10 07:34:05 tom Exp $ */
27 static const unsigned char base64_enc_map
[64] =
29 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
30 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
31 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
32 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
33 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
34 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
38 static const unsigned char base64_dec_map
[128] =
40 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
41 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
42 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
43 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
44 127, 127, 127, 62, 127, 127, 127, 63, 52, 53,
45 54, 55, 56, 57, 58, 59, 60, 61, 127, 127,
46 127, 64, 127, 127, 127, 0, 1, 2, 3, 4,
47 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
48 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
49 25, 127, 127, 127, 127, 127, 127, 26, 27, 28,
50 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
51 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
52 49, 50, 51, 127, 127, 127, 127, 127
56 * Encode a buffer into base64 format
58 int base64_encode( unsigned char *dst
, int *dlen
,
59 unsigned char *src
, int slen
)
70 switch( (slen
<< 3) - (n
* 6) )
72 case 2: n
+= 3; break;
73 case 4: n
+= 2; break;
80 return( POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL
);
85 for( i
= 0, p
= dst
; i
< n
; i
+= 3 )
91 *p
++ = base64_enc_map
[(C1
>> 2) & 0x3F];
92 *p
++ = base64_enc_map
[(((C1
& 3) << 4) + (C2
>> 4)) & 0x3F];
93 *p
++ = base64_enc_map
[(((C2
& 15) << 2) + (C3
>> 6)) & 0x3F];
94 *p
++ = base64_enc_map
[C3
& 0x3F];
100 C2
= ((i
+ 1) < slen
) ? *src
++ : 0;
102 *p
++ = base64_enc_map
[(C1
>> 2) & 0x3F];
103 *p
++ = base64_enc_map
[(((C1
& 3) << 4) + (C2
>> 4)) & 0x3F];
106 *p
++ = base64_enc_map
[((C2
& 15) << 2) & 0x3F];
119 * Decode a base64-formatted buffer
121 int base64_decode( unsigned char *dst
, int *dlen
,
122 unsigned char *src
, int slen
)
128 for( i
= j
= n
= 0; i
< slen
; i
++ )
130 if( ( slen
- i
) >= 2 &&
131 src
[i
] == '\r' && src
[i
+ 1] == '\n' )
137 if( src
[i
] == '=' && ++j
> 2 )
138 return( POLARSSL_ERR_BASE64_INVALID_CHARACTER
);
140 if( src
[i
] > 127 || base64_dec_map
[src
[i
]] == 127 )
141 return( POLARSSL_ERR_BASE64_INVALID_CHARACTER
);
143 if( base64_dec_map
[src
[i
]] < 64 && j
!= 0 )
144 return( POLARSSL_ERR_BASE64_INVALID_CHARACTER
);
152 n
= ((n
* 6) + 7) >> 3;
157 return( POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL
);
160 for( j
= 3, n
= x
= 0, p
= dst
; i
> 0; i
--, src
++ )
162 if( *src
== '\r' || *src
== '\n' )
165 j
-= ( base64_dec_map
[*src
] == 64 );
166 x
= (x
<< 6) | ( base64_dec_map
[*src
] & 0x3F );
171 if( j
> 0 ) *p
++ = (unsigned char)( x
>> 16 );
172 if( j
> 1 ) *p
++ = (unsigned char)( x
>> 8 );
173 if( j
> 2 ) *p
++ = (unsigned char)( x
);