1 /*!
2 \file b64.c
3 \brief This file contains some simple 8bit-to-6bit encoding/deconding routines
4
5 Most of these routines are outdated and should be converted using glibc's equivalent
6 routines.
7
8 \date Started 2/22/05
9 \author George
10 \version\verbatim $Id: b64.c 10711 2011-08-31 22:23:04Z karypis $ \endverbatim
11
12 \verbatim
13 $Copyright$
14 $License$
15 \endverbatim
16
17 */
18
19
20 #include "GKlib.h"
21
22 #define B64OFFSET 48 /* This is the '0' number */
23
24
25 /******************************************************************************
26 * Encode 3 '8-bit' binary bytes as 4 '6-bit' characters
27 *******************************************************************************/
encodeblock(unsigned char * in,unsigned char * out)28 void encodeblock(unsigned char *in, unsigned char *out)
29 {
30 out[0] = (in[0] >> 2);
31 out[1] = (((in[0] & 0x03) << 4) | (in[1] >> 4));
32 out[2] = (((in[1] & 0x0f) << 2) | (in[2] >> 6));
33 out[3] = (in[2] & 0x3f);
34
35 out[0] += B64OFFSET;
36 out[1] += B64OFFSET;
37 out[2] += B64OFFSET;
38 out[3] += B64OFFSET;
39
40 // printf("%c %c %c %c %2x %2x %2x %2x %2x %2x %2x\n", out[0], out[1], out[2], out[3], out[0], out[1], out[2], out[3], in[0], in[1], in[2]);
41 }
42
43 /******************************************************************************
44 * Decode 4 '6-bit' characters into 3 '8-bit' binary bytes
45 *******************************************************************************/
decodeblock(unsigned char * in,unsigned char * out)46 void decodeblock(unsigned char *in, unsigned char *out)
47 {
48 in[0] -= B64OFFSET;
49 in[1] -= B64OFFSET;
50 in[2] -= B64OFFSET;
51 in[3] -= B64OFFSET;
52
53 out[0] = (in[0] << 2 | in[1] >> 4);
54 out[1] = (in[1] << 4 | in[2] >> 2);
55 out[2] = (in[2] << 6 | in[3]);
56 }
57
58
59 /******************************************************************************
60 * This function encodes an input array of bytes into a base64 encoding. Memory
61 * for the output array is assumed to have been allocated by the calling program
62 * and be sufficiently large. The output string is NULL terminated.
63 *******************************************************************************/
GKEncodeBase64(int nbytes,unsigned char * inbuffer,unsigned char * outbuffer)64 void GKEncodeBase64(int nbytes, unsigned char *inbuffer, unsigned char *outbuffer)
65 {
66 int i, j;
67
68 if (nbytes%3 != 0)
69 gk_errexit(SIGERR, "GKEncodeBase64: Input buffer size should be a multiple of 3! (%d)\n", nbytes);
70
71 for (j=0, i=0; i<nbytes; i+=3, j+=4)
72 encodeblock(inbuffer+i, outbuffer+j);
73
74 //printf("%d %d\n", nbytes, j);
75 outbuffer[j] = '\0';
76 }
77
78
79
80 /******************************************************************************
81 * This function decodes an input array of base64 characters into their actual
82 * 8-bit codes. Memory * for the output array is assumed to have been allocated
83 * by the calling program and be sufficiently large. The padding is discarded.
84 *******************************************************************************/
GKDecodeBase64(int nbytes,unsigned char * inbuffer,unsigned char * outbuffer)85 void GKDecodeBase64(int nbytes, unsigned char *inbuffer, unsigned char *outbuffer)
86 {
87 int i, j;
88
89 if (nbytes%4 != 0)
90 gk_errexit(SIGERR, "GKDecodeBase64: Input buffer size should be a multiple of 4! (%d)\n", nbytes);
91
92 for (j=0, i=0; i<nbytes; i+=4, j+=3)
93 decodeblock(inbuffer+i, outbuffer+j);
94 }
95
96