By default many of the programs used for authoring TrueType fonts set the "allow embedding" bits to false. Because this is an obscure setting it is often overlooked and thus many fonts that were not intended to be restricted have been released with it set. Embed flips these bits so that software which actually pays attention to them (such as Adobe Distiller) will play nice.
See Cracking TrueType Fonts or the official embed site (http://www.andrew.cmu.edu/~twm/embed/) for more information.
This is the source code for the embed utility. The author claims that this requires a 32 bit Windows or a DOS extender (cwsdpmi.exe) to run, but my theory is that it will work flawlessly under WINE or any DOS emulator that supports extenders.
/*
* This program is for setting TTF files to Installable Embedding mode.
*
* Note that using this to embed fonts which you are not licensed to embed
* does not make it legal.
*
* This code was written by Tom Murphy 7, and is public domain. Use at your
* own risk...
*/
#include <stdio.h>
#include <stdlib.h>
void fatal();
int main (int argc, char**argv) {
FILE * inways;
if (argc != 2)
printf("Usage: %s font.ttf\n\nPublic Domain software by Tom 7.
Use at your own risk.\n",argv[0]);
else if (inways = fopen(argv[1],"rb+")) {
int a,x;
char type[5];
type[4]=0;
fseek(inways,12,0);
for (;;) {
for (x=0;x<4;x++) if (EOF == (type[x] = getc(inways))) fatal();
if (!strcmp(type,"OS/2")) {
int length;
unsigned long loc, fstype, sum=0;
loc=ftell(inways); /* location for checksum */
for (x=4;x--;) if (EOF == getc(inways)) fatal();
fstype = fgetc(inways) << 24;
fstype |= fgetc(inways) << 16;
fstype |= fgetc(inways) << 8 ;
fstype |= fgetc(inways) ;
length = fgetc(inways) << 24;
length |= fgetc(inways) << 16;
length |= fgetc(inways) << 8 ;
length |= fgetc(inways) ;
/* printf("fstype: %d length: %d\n",fstype,length);*/
if (fseek(inways,fstype+8,0)) fatal();
fputc(0,inways);
fputc(0,inways);
fseek(inways,fstype,0);
for (x=length;x--;)
sum += fgetc(inways);
fseek(inways,loc,0); /* write checksum */
fputc(sum>>24,inways);
fputc(255&(sum>>16),inways);
fputc(255&(sum>>8), inways);
fputc(255&sum , inways);
fclose(inways);
exit(0);
}
for (x=12;x--;) if (EOF == getc(inways)) fatal();
}
} else
printf("I wasn't able to open the file %s.\n", argv[1]);
}
void fatal() { fprintf(stderr,"Malformed TTF file.\n");
exit(-1); }