The python-asn1 documentation indicates that end of file may be
detected either by obtaining a True value from .eof() or by obtaining
a None value from .peek(), but does not mention any way to detect the
end of a constructed tag (rather than the end of the overall file).
We currently use .eof() to detect the end of a constructed tag, based
on the observed behaviour of the library.
The behaviour of .eof() changed between versions 2.8.0 and 3.0.0, such
that .eof() no longer returns True at the end of a constructed tag.
Switch to testing for a None value returned from .peek() to determine
when we have reached the end of a constructed tag, since this works on
both newer and older versions.
Continue to treat .eof() as a necessary but not sufficient condition
for reaching the overall end of file, to maintain compatibility with
older versions.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The openssl toolchain does not currently seem to support creating CMS
envelopedData or authEnvelopedData messages with detached encrypted
data.
Add a standalone tool "cmsdetach" that can be used to detach the
encrypted data from a CMS message. For example:
openssl cms -encrypt -binary -aes-256-gcm -recip client.crt \
-in bootfile -outform DER -out bootfile.cms
cmsdetach bootfile.cms --data bootfile.dat --envelope bootfile.env
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown