README

   1 shim is a trivial EFI application that, when run, attempts to open and
   2 execute another application. It will initially attempt to do this via the
   3 standard EFI LoadImage() and StartImage() calls. If these fail (because secure
   4 boot is enabled and the binary is not signed with an appropriate key, for
   5 instance) it will then validate the binary against a built-in certificate. If
   6 this succeeds and if the binary or signing key are not blacklisted then shim
   7 will relocate and execute the binary.
   8
   9 shim will also install a protocol which permits the second-stage bootloader
  10 to perform similar binary validation. This protocol has a GUID as described
  11 in the shim.h header file and provides a single entry point. On 64-bit systems
  12 this entry point expects to be called with SysV ABI rather than MSABI, and
  13 so calls to it should not be wrapped.
  14
  15 To use shim, simply place a DER-encoded public certificate in a file such as
  16 pub.cer and build with "make VENDOR_CERT_FILE=pub.cer".