<s>
The	O
RC	B-Algorithm
algorithms	I-Algorithm
are	O
a	O
set	O
of	O
symmetric-key	B-Algorithm
encryption	I-Algorithm
algorithms	I-Algorithm
invented	O
by	O
Ron	O
Rivest	O
.	O
</s>
<s>
The	O
"	O
RC	O
"	O
may	O
stand	O
for	O
either	O
Rivest	B-Algorithm
's	I-Algorithm
cipher	I-Algorithm
or	O
,	O
more	O
informally	O
,	O
Ron	B-Algorithm
's	I-Algorithm
code	I-Algorithm
.	O
</s>
<s>
There	O
have	O
been	O
six	O
RC	B-Algorithm
algorithms	I-Algorithm
so	O
far	O
:	O
</s>
<s>
RC2	B-Algorithm
was	O
a	O
64-bit	O
block	O
cipher	O
developed	O
in	O
1987	O
.	O
</s>
<s>
RC4	B-Algorithm
is	O
a	O
stream	B-Algorithm
cipher	I-Algorithm
.	O
</s>
<s>
RC5	B-Algorithm
is	O
a	O
32/64/128	O
-bit	O
block	O
cipher	O
developed	O
in	O
1994	O
.	O
</s>
<s>
RC6	B-Algorithm
,	O
a	O
128-bit	O
block	O
cipher	O
based	O
heavily	O
on	O
RC5	B-Algorithm
,	O
was	O
an	O
AES	O
finalist	O
developed	O
in	O
1997	O
.	O
</s>
