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-rw-r--r--libqpdf/qpdf/auto_job_help.hh6
1 files changed, 4 insertions, 2 deletions
diff --git a/libqpdf/qpdf/auto_job_help.hh b/libqpdf/qpdf/auto_job_help.hh
index 71e49f3c..e3759115 100644
--- a/libqpdf/qpdf/auto_job_help.hh
+++ b/libqpdf/qpdf/auto_job_help.hh
@@ -397,8 +397,10 @@ ap.addHelpTopic("encryption", "create encrypted files", R"(Create encrypted file
--encrypt user-password owner-password key-length [options] --
Either or both of user-password and owner-password may be empty
-strings. key-length may be 40, 128, or 256. Encryption options are
-terminated by "--" by itself.
+strings, though setting either to the empty string enables the file
+to be opened and decrpyted without a password. key-length may be
+40, 128, or 256. Encryption options are terminated by "--" by
+itself.
40-bit encryption is insecure, as is 128-bit encryption without
AES. Use 256-bit encryption unless you have a specific reason to