Extract the IDC-parsing code from IDC_check_hash, and use it to
initialise a BIO. This BIO can then be used to perform the PKCS7
verification.
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Add a check to match the calculated image's hash against the one found
in the PKCS7 IndirectDataContext
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
GPLv3; the sources include parts of binutils, include parts of ccan,
and have been partially based of osslsigntool.
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
