mirror of
https://github.com/qpdf/qpdf.git
synced 2024-11-18 02:25:08 +00:00
34 lines
1.5 KiB
ReStructuredText
34 lines
1.5 KiB
ReStructuredText
.. _weak-crypto:
|
|
|
|
Weak Cryptography
|
|
=================
|
|
|
|
Start with version 10.4, qpdf is taking steps to reduce the likelihood
|
|
of a user *accidentally* creating PDF files with insecure cryptography
|
|
but will continue to allow creation of such files indefinitely with
|
|
explicit acknowledgment.
|
|
|
|
The PDF file format makes use of RC4, which is known to be a weak
|
|
cryptography algorithm, and MD5, which is a weak hashing algorithm. In
|
|
version 10.4, qpdf generates warnings for some (but not all) cases of
|
|
writing files with weak cryptography when invoked from the command-line.
|
|
These warnings can be suppressed using the
|
|
:samp:`--allow-weak-crypto` option.
|
|
|
|
It is planned for qpdf version 11 to be stricter, making it an error to
|
|
write files with insecure cryptography from the command-line tool in
|
|
most cases without specifying the
|
|
:samp:`--allow-weak-crypto` flag and also to require
|
|
explicit steps when using the C++ library to enable use of insecure
|
|
cryptography.
|
|
|
|
Note that qpdf must always retain support for weak cryptographic
|
|
algorithms since this is required for reading older PDF files that use
|
|
it. Additionally, qpdf will always retain the ability to create files
|
|
using weak cryptographic algorithms since, as a development tool, qpdf
|
|
explicitly supports creating older or deprecated types of PDF files
|
|
since these are sometimes needed to test or work with older versions of
|
|
software. Even if other cryptography libraries drop support for RC4 or
|
|
MD5, qpdf can always fall back to its internal implementations of those
|
|
algorithms, so they are not going to disappear from qpdf.
|