<s>
In	O
cryptography	O
,	O
residual	B-Algorithm
block	I-Algorithm
termination	I-Algorithm
is	O
a	O
variation	O
of	O
cipher	O
block	O
chaining	O
mode	B-Algorithm
(	O
CBC	O
)	O
that	O
does	O
not	O
require	O
any	O
padding	B-Algorithm
.	O
</s>
<s>
It	O
does	O
this	O
by	O
effectively	O
changing	O
to	O
cipher	O
feedback	O
mode	B-Algorithm
for	O
one	O
block	O
.	O
</s>
<s>
Encrypt	O
the	O
⌊	O
N/L	O
⌋	O
full	O
blocks	O
of	O
plaintext	O
using	O
the	O
cipher	O
block	O
chaining	O
mode	B-Algorithm
;	O
</s>
<s>
XOR	B-Application
the	O
remaining	O
bits	O
of	O
the	O
plaintext	O
with	O
leftmost	O
bits	O
of	O
the	O
re-encrypted	O
block	O
.	O
</s>
<s>
Decrypt	O
the	O
⌊	O
N/L	O
⌋	O
full	O
encrypted	O
blocks	O
using	O
the	O
Cipher	O
Block	O
Chaining	O
mode	B-Algorithm
;	O
</s>
<s>
XOR	B-Application
the	O
remaining	O
bits	O
of	O
the	O
ciphertext	O
with	O
leftmost	O
bits	O
of	O
the	O
re-encrypted	O
block	O
.	O
</s>
<s>
For	O
messages	O
shorter	O
than	O
one	O
block	O
,	O
residual	B-Algorithm
block	I-Algorithm
termination	I-Algorithm
can	O
use	O
an	O
encrypted	O
IV	B-Algorithm
instead	O
of	O
the	O
previously	O
encrypted	O
block	O
.	O
</s>
