BrowserUk:

A relatively simple C program to do the task:

roboticus@Boink~
$ cat 876421.cpp
#include <stdio.h>

unsigned char inbuf[]="Now is the time for all ";
unsigned char outbuf[50];

void hexdump(unsigned char *p, int n) {
    for (int i=0; i<n; i++) {
        printf("%02x ", *p++);
    }
    puts("\n");
}

int main(int, char **) {
    unsigned char *src = inbuf;
    unsigned char *srcEnd = src + sizeof(inbuf);
    unsigned char *dst = outbuf;
    hexdump(src, sizeof(inbuf));
    int rem = 0;
    int st = 0;
    while (src != srcEnd) {
        switch (st) {
            case 0:
                rem = *src >> 6;
                *dst++ = *src++ & 0x3f;
                st = 1;
                break;
            case 1:
                *dst++ = ((*src&0x0f)<<2)  | rem;
                rem = *src++>>4;
                st = 2;
                break;
            case 2:
                *dst++ = ((*src&0x03)<<4) | rem;
                *dst++ = *src++>>2;
                st = 0;
                break;
        }
    }

    hexdump(outbuf, dst-outbuf);
}

roboticus@Boink~marco@Boink:~
$ gcc 876421.cpp -lstdc++

roboticus@Boink:~
$ ./a.out 
4e 6f 77 20 69 73 20 74 68 65 20 74 69 6d 65 20 66 6f 72 20 61 6c 6c 2
+0 00 

0e 3d 36 1d 20 24 36 1c 20 10 07 1a 25 01 02 1d 29 35 16 19 20 18 36 1
+b 32 01 12 18 2c 31 06 08 00
[download]

...roboticus

When your only tool is a hammer, all problems look like your thumb.