md5crypt.cc

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#include <stdlib.h>
#include "md5.h"
#include "md5crypt.h"

#define Assert(Cond) if (!(Cond)) abort()

static const char Base64[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static const char Pad64 = '=';

//#define u_char unsigned char
int b64_ntop(u_char const *src,
             size_t srclength, char *target, size_t targsize)
{
        size_t datalength = 0;
        u_char input[3];
        u_char output[4];
        size_t i;

        while (2 < srclength) {
                input[0] = *src++;
                input[1] = *src++;
                input[2] = *src++;
                srclength -= 3;

                output[0] = input[0] >> 2;
                output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
                output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
                output[3] = input[2] & 0x3f;
                Assert(output[0] < 64);
                Assert(output[1] < 64);
                Assert(output[2] < 64);
                Assert(output[3] < 64);

                if (datalength + 4 > targsize)
                        return (-1);
                target[datalength++] = Base64[output[0]];
                target[datalength++] = Base64[output[1]];
                target[datalength++] = Base64[output[2]];
                target[datalength++] = Base64[output[3]];
        }

        /* Now we worry about padding. */
        if (0 != srclength) {
                /* Get what's left. */
                input[0] = input[1] = input[2] = '\0';
                for (i = 0; i < srclength; i++)
                        input[i] = *src++;

                output[0] = input[0] >> 2;
                output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
                output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
                Assert(output[0] < 64);
                Assert(output[1] < 64);
                Assert(output[2] < 64);

                if (datalength + 4 > targsize)
                        return (-1);
                target[datalength++] = Base64[output[0]];
                target[datalength++] = Base64[output[1]];
                if (srclength == 1)
                        target[datalength++] = Pad64;
                else
                        target[datalength++] = Base64[output[2]];
                target[datalength++] = Pad64;
        }
        if (datalength >= targsize)
                return (-1);
        target[datalength] = '\0';      /* Returned value doesn't count \0. */
        return (datalength);
}

char *md5crypt(const char *password)
{
        MD5_CTX MD5context;
        unsigned char MD5digest[16];
        char base64digest[25];  /* ceiling(sizeof(input)/3) * 4 + 1 */

        MD5Init(&MD5context);
        MD5Update(&MD5context,
                  (const unsigned char *) password, strlen(password));
        MD5Final(MD5digest, &MD5context);
        if (b64_ntop(MD5digest, sizeof(MD5digest),
                     base64digest, sizeof(base64digest)) < 0) {
                return (NULL);
        }
        return (strdup(base64digest));

}

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