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Diffstat (limited to 'manual/qpdf-manual.xml')
| -rw-r--r-- | manual/qpdf-manual.xml | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/manual/qpdf-manual.xml b/manual/qpdf-manual.xml index 13008ef9..98ce8afa 100644 --- a/manual/qpdf-manual.xml +++ b/manual/qpdf-manual.xml @@ -874,6 +874,19 @@ make </listitem> </varlistentry> <varlistentry> + <term><option>--allow-weak-crypto</option></term> + <listitem> + <para> + Starting with version 10.4, qpdf issues warnings when + requested to create files using RC4 encryption. This option + suppresses those warnings. In future versions of qpdf, qpdf + will refuse to create files with weak cryptography when this + flag is not given. See <xref linkend="ref.weak-crypto"/> for + additional details. + </para> + </listitem> + </varlistentry> + <varlistentry> <term><option>--encrypt options --</option></term> <listitem> <para> @@ -3355,6 +3368,43 @@ outfile.pdf</option> </para> </sect1> </chapter> + <chapter id="ref.weak-crypto"> + <title>Weak Cryptography</title> + <para> + Start with version 10.4, qpdf is taking steps to reduce the + likelihood of a user <emphasis>accidentally</emphasis> creating PDF + files with insecure cryptography but will continue to allow + creation of such files indefinitely with explicit acknowledgment. + </para> + <para> + 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 + <option>--allow-weak-crypto</option> option. + </para> + <para> + 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 + <option>--allow-weak-crypto</option> flag and also to require + explicit steps when using the C++ library to enable use of insecure + cryptography. + </para> + <para> + 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. + </para> + </chapter> <chapter id="ref.json"> <title>QPDF JSON</title> <sect1 id="ref.json-overview"> @@ -5072,6 +5122,27 @@ print "\n"; <itemizedlist> <listitem> <para> + Handling of Weak Cryptography Algorithms + </para> + <itemizedlist> + <listitem> + <para> + From the qpdf CLI, the <option>--allow-weak-crypto</option> + is now required to suppress a warning when explicitly + creating PDF files using RC4 encryption. While qpdf will + always retain the ability to read and write such files, + doing so will require explicit acknowledgment moving + forward. For qpdf 10.4, this change only affects the + command-line tool. Starting in qpdf 11, there will be small + API changes to require explicit acknowledgment in those + cases as well. For additional information, see <xref + linkend="ref.weak-crypto"/>. + </para> + </listitem> + </itemizedlist> + </listitem> + <listitem> + <para> Bug Fixes </para> <itemizedlist> |