Hi--
the serpent cipher is unusable at the moment in sid.
Linux pharoah 4.14.0-3-amd64 #1 SMP Debian 4.14.13-1 (2018-01-14) x86_64 GNU/Linux
# modprobe serpent
modprobe: ERROR: could not insert 'serpent_sse2_x86_64': Unknown symbol in module, or unknown parameter (see dmesg)
modprobe: ERROR: could not insert 'serpent_avx_x86_64': Unknown symbol in module, or unknown parameter (see dmesg)
modprobe: ERROR: could not insert 'serpent_avx2': Unknown symbol in module, or unknown parameter (see dmesg)
syslog has:
Feb 16 10:18:44 pharoah kernel: [16131.500226] ablk_helper: Unknown symbol __x86_indirect_thunk_rax (err 0)
Feb 16 10:18:44 pharoah kernel: [16131.520670] ablk_helper: Unknown symbol __x86_indirect_thunk_rax (err 0)
Feb 16 10:18:44 pharoah kernel: [16131.548529] ablk_helper: Unknown symbol __x86_indirect_thunk_rax (err 0)