--hello-string

#include "crypto-base64.h"

#include <ctype.h>

#include <stdlib.h>

#include <string.h>

#include <stdio.h>

/****************************************************************************

 ****************************************************************************/

size_t

base64_encode(void *vdst, size_t sizeof_dst, const void *vsrc, size_t sizeof_src)

{

    static const char *b64 =

        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

        "abcdefghijklmnopqrstuvwxyz"

        "0123456789"

        "+/";

    size_t i = 0;

    size_t d = 0;

    unsigned char *dst = (unsigned char *)vdst;

    const unsigned char *src = (const unsigned char *)vsrc;

    while (i + 3 <= sizeof_src) {

        unsigned n;

        /* make sure there is enough space */

        if (d + 4 > sizeof_dst)

            return d;

        /* conver the chars */

        n = src[i]<<16 | src[i+1]<<8 | src[i+2];

        dst[d+0] = b64[ (n>>18) & 0x3F ];

        dst[d+1] = b64[ (n>>12) & 0x3F ];

        dst[d+2] = b64[ (n>> 6) & 0x3F ];

        dst[d+3] = b64[ (n>> 0) & 0x3F ];

        i += 3;

        d += 4;

    }

    if (i + 2 <= sizeof_src && d + 4 <= sizeof_dst) {

        unsigned n = src[i]<<16 | src[i+1]<<8;

        dst[d+0] = b64[ (n>>18) & 0x3F ];

        dst[d+1] = b64[ (n>>12) & 0x3F ];

        dst[d+2] = b64[ (n>> 6) & 0x3F ];

        dst[d+3] = '=';

        d += 4;

    } else if (i + 1 <= sizeof_src && d + 4 <= sizeof_dst) {

        unsigned n = src[i]<<16 | src[i+1]<<8;

        dst[d+0] = b64[ (n>>18) & 0x3F ];

        dst[d+1] = b64[ (n>>12) & 0x3F ];

        dst[d+2] = '=';

        dst[d+3] = '=';

        d += 4;

    }

    return d;

}

/****************************************************************************

 ****************************************************************************/

size_t

base64_decode(void *vdst, size_t sizeof_dst, const void *vsrc, size_t sizeof_src)

{

	static const unsigned char rstr[] = {

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,	62,		0xFF,   0xFF,   0xFF,	63,

		52,		53,		54,		55,		56,		57,		58,		59,		60,		61,		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0,		1,		2,		3,		4,		5,		6,		7,		8,		9,		10,		11,		12,		13,		14,

		15,		16,		17,		18,		19,		20,		21,		22,		23,		24,		25,		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,	26,		27,		28,		29,		30,		31,		32,		33,		34,		35,		36,		37,		38,		39,		40,

		41,		42,		43,		44,		45,		46,		47,		48,		49,		50,		51,		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

		0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,   0xFF,

	};

    size_t i = 0;

    size_t d = 0;

    unsigned char *dst = (unsigned char *)vdst;

    const unsigned char *src = (const unsigned char *)vsrc;

	while (i < sizeof_src) {

        unsigned b;

		unsigned c=0;

		/* byte#1 */

		while (i<sizeof_src && (c = rstr[src[i]]) > 64)

			i++;

		if (src[i] == '=' || i++ >= sizeof_src)

			break;

		b = (c << 2) & 0xfc;

		while (i<sizeof_src && (c = rstr[src[i]]) > 64)

			i++;

		if (src[i] == '=' || i++ >= sizeof_src)

			break;

		b |= (c>>4) & 0x03;

		if (d<sizeof_dst)

			dst[d++] = (unsigned char)b;

		if (i>=sizeof_src)

			break;

		/* byte#2 */

		b = (c<<4) & 0xF0;

		while (i<sizeof_src && src[i] != '=' && (c = rstr[src[i]]) > 64)

			;

		if (src[i] == '=' || i++ >= sizeof_src)

			break;

		b |= (c>>2) & 0x0F;

		if (d<sizeof_dst)

			dst[d++] = (unsigned char)b;

		if (i>=sizeof_src)

			break;

		/* byte#3*/

		b = (c<<6) & 0xC0;

		while (i<sizeof_src && src[i] != '=' && (c = rstr[src[i]]) > 64)

			;

		if (src[i] == '=' || i++ >= sizeof_src)

			break;

		b |= c;

		if (d<sizeof_dst)

			dst[d++] = (unsigned char)b;

		if (i>=sizeof_src)

			break;

	}

	if (d<sizeof_dst)

		dst[d] = '\0';

	return d;

}

int

base64_selftest(void)

{

    char buf[100];

    char buf2[100];

    size_t buf_len;

    size_t buf2_len;

    buf_len = base64_encode(buf, sizeof(buf), "hello", 5);

    buf2_len = base64_decode(buf2, sizeof(buf2), buf, buf_len);

    if (buf2_len != 5 && memcmp(buf2, "hello", 5) != 0) {

        fprintf(stderr, "base64: selftest failed\n");

        return 1;

    }

    return 0;

}

#ifndef CRYPTO_BASE64_H

#define CRYPTO_BASE64_H

size_t base64_decode(void *dst, size_t sizeof_dst, const void *src, size_t sizeof_src);

size_t base64_encode(void *dst, size_t sizeof_dst, const void *src, size_t sizeof_src);

int base64_selftest(void);

#endif