In Radix-64 data, characters other than those in the table, line breaks, and other white space probably indicate a transmission error, about which a warning message or even a message rejection might be appropriate under some circumstances. Decoding software must ignore all white space.
GnuPG ignores all white space, so it is able to successfully decrypt this unusual-but-compliant message (password is "test"):
RFC4880 section 6.4 states:
GnuPG ignores all white space, so it is able to successfully decrypt this unusual-but-compliant message (password is "test"):
However, pgpdump currently cannot parse it. This patch changes pgpdump to ignore spaces and tabs, which fixes the problem.