The only user of PCBC mode (Propagating Cipher Block Chaining mode) was
net/rxrpc/rxkad.c, which now uses local code instead.
While PCBC was an interesting cryptographic experiment, it has largely
been relegated to the history books and academic exercises. It is
non-parallelizable (i.e., very slow) and doesn't actually achieve the
integrity properties it was apparently intended to achieve.
Remove support for it from the crypto API.
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Tested-by: Marc Dionne <marc.dionne@auristor.com>
Link: https://patch.msgid.link/20260522050740.84561-6-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>