libeot

A small C library (and eot2ttf tool) that unpacks Embedded OpenType fonts into plain TrueType.

Fork note: this is a fork of umanwizard/libeot, written by Brennan T. Vincent with contributions from David Tardon. All credit goes to the original authors; this fork only adds documentation.

Embedded OpenType (.eot) is Microsoft's web-font format from the Internet Explorer era. It wraps a TrueType font with a header (names, permissions, the sites allowed to use it) and can obfuscate and compress the font data. Modern browsers use WOFF/WOFF2 instead, but old sites and documents still carry .eot files.

libeot reads an .eot file, parses its header, undoes the encoding and gives you back a normal .ttf font you can open or convert with any font tool.

• Parses EOT headers, versions 0x00010000, 0x00020001 and 0x00020002 (EOT v1, v2, v3)
• Exposes the metadata: family/style/full/version names, weight, italic, PANOSE, charset, Unicode and code-page ranges, embedding permissions, allowed root URLs, EUDC info
• Removes XOR obfuscation (TTEMBED_XORENCRYPTDATA, key 0x50)
• Decompresses MicroType Express (MTX) fonts: LZCOMP + Compact Font Format (CTF) back to TrueType
• Writes the result to a FILE * or a memory buffer
• eot2ttf command-line converter
• pkg-config file (libeot.pc)

Not supported: AccuType (ACT) compression and writing new .eot files.

Needs a C99 compiler and autotools (autoconf, automake, libtool).

1. autoreconf --install
2. ./configure
3. make

make install installs libeot, the headers under include/libeot/ and the eot2ttf binary.

eot2ttf myfont.eot myfont.ttf

#include <stdio.h>
#include <libeot/libeot.h>

/* eot: the whole .eot file in memory, eotSize: its length in bytes */
int convert(const uint8_t *eot, unsigned eotSize)
{
  struct EOTMetadata meta;
  uint8_t *ttf;
  unsigned ttfSize;

  enum EOTError err = EOT2ttf_buffer(eot, eotSize, &meta, &ttf, &ttfSize);
  if (err != EOT_SUCCESS) {
    EOTprintError(err, stderr);
    return 1;
  }

  /* ... use ttf / ttfSize, read meta.familyName, meta.weight, ... */

  EOTfreeBuffer(ttf);
  EOTfreeMetadata(&meta);
  return 0;
}

Link with $(pkg-config --cflags --libs libeot).

Headers: libeot/libeot.h (conversion), libeot/EOT.h (metadata), libeot/EOTError.h (error codes).

Mozilla Public License 2.0. The MTX decompressor in src/lzcomp comes from Monotype's MTX reference code and was relicensed under the MPL (see the notice at the top of LICENSE). Please also read PATENTS about the Microsoft/Monotype patents around EOT.

• Original author: Brennan T. Vincent (umanwizard/libeot)
• Contributor: David Tardon
• MTX/LZCOMP code: Monotype Imaging