<s>
Cryptographic	B-Algorithm
agility	I-Algorithm
(	O
also	O
referred	O
to	O
as	O
crypto-agility	B-Algorithm
)	O
is	O
a	O
practice	O
paradigm	O
in	O
designing	O
information	O
security	O
protocols	O
and	O
standards	O
in	O
a	O
way	O
so	O
that	O
they	O
can	O
support	O
multiple	O
cryptographic	O
primitives	O
and	O
algorithms	O
at	O
the	O
same	O
time	O
.	O
</s>
<s>
The	O
primary	O
goal	O
of	O
cryptographic	B-Algorithm
agility	I-Algorithm
was	O
to	O
enable	O
rapid	O
adaptations	O
of	O
new	O
cryptographic	O
primitives	O
and	O
algorithms	O
without	O
making	O
disruptive	O
changes	O
to	O
the	O
systems	O
 '	O
infrastructure	O
.	O
</s>
<s>
Cryptographic	B-Algorithm
agility	I-Algorithm
acts	O
as	O
a	O
safety	O
measure	O
or	O
an	O
incident	O
response	O
mechanism	O
when	O
a	O
cryptographic	O
primitive	O
of	O
a	O
system	O
is	O
discovered	O
to	O
be	O
vulnerable	O
.	O
</s>
<s>
The	O
impending	O
arrival	O
of	O
a	O
quantum	B-Architecture
computer	I-Architecture
that	O
can	O
break	O
existing	O
asymmetric	O
cryptography	O
is	O
raising	O
awareness	O
of	O
the	O
importance	O
of	O
cryptographic	B-Algorithm
agility	I-Algorithm
.	O
</s>
<s>
The	O
X.509	O
public	O
key	O
certificate	O
illustrates	O
crypto-agility	B-Algorithm
.	O
</s>
<s>
A	O
public	O
key	O
certificate	O
has	O
cryptographic	O
parameters	O
including	O
key	O
type	O
,	O
key	O
length	O
,	O
and	O
a	O
hash	B-Error_Name
algorithm	I-Error_Name
.	O
</s>
<s>
X.509	O
version	O
v.3	O
,	O
with	O
key	O
type	O
RSA	B-Architecture
,	O
a	O
1024-bit	O
key	O
length	O
,	O
and	O
the	O
SHA-1	O
hash	B-Error_Name
algorithm	I-Error_Name
were	O
found	O
by	O
NIST	O
to	O
have	O
a	O
key	O
length	O
that	O
made	O
it	O
vulnerable	O
to	O
attacks	O
,	O
thus	O
prompting	O
the	O
transition	O
to	O
SHA-2	O
.	O
</s>
<s>
With	O
the	O
rise	O
of	O
secure	B-Protocol
transport	I-Protocol
layer	I-Protocol
communication	I-Protocol
in	O
the	O
end	O
of	O
the	O
1990s	O
,	O
cryptographic	O
primitives	O
and	O
algorithms	O
have	O
been	O
increasingly	O
more	O
popular	O
;	O
as	O
an	O
example	O
,	O
by	O
2019	O
more	O
than	O
80%	O
of	O
all	O
website	O
employed	O
some	O
form	O
of	O
security	O
measures	O
.	O
</s>
<s>
Crypto-agility	B-Algorithm
tries	O
to	O
tackle	O
the	O
implied	O
threat	O
to	O
information	O
security	O
by	O
allowing	O
swift	O
deprecation	O
of	O
vulnerable	O
primitives	O
and	O
replacement	O
by	O
new	O
ones	O
.	O
</s>
<s>
This	O
threat	O
is	O
not	O
merely	O
theoretical	O
;	O
many	O
algorithms	O
that	O
were	O
once	O
considered	O
secure	O
(	O
DES	B-Algorithm
,	O
512	O
bit	O
RSA	B-Architecture
,	O
RC4	B-Algorithm
)	O
are	O
now	O
known	O
to	O
be	O
vulnerable	O
,	O
some	O
even	O
to	O
amateur	O
attackers	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
new	O
algorithms	O
(	O
AES	B-Algorithm
,	O
Elliptic	O
Curve	O
Cryptography	O
)	O
are	O
often	O
both	O
more	O
secure	O
and	O
faster	O
in	O
comparison	O
to	O
old	O
ones	O
.	O
</s>
<s>
Systems	O
designed	O
to	O
meet	O
crypto-agility	B-Algorithm
criteria	O
are	O
expected	O
to	O
be	O
less	O
affected	O
should	O
current	O
primitives	O
are	O
found	O
vulnerable	O
,	O
and	O
may	O
enjoy	O
better	O
latency	O
or	O
battery	O
usage	O
by	O
using	O
new	O
and	O
improved	O
primitives	O
.	O
</s>
<s>
As	O
an	O
example	O
,	O
quantum	B-Architecture
computing	I-Architecture
,	O
if	O
feasible	O
,	O
is	O
expected	O
to	O
be	O
able	O
to	O
defeat	O
existing	O
public	O
key	O
cryptography	O
algorithms	O
.	O
</s>
<s>
Quantum	B-Architecture
computers	I-Architecture
running	O
Shor	B-Algorithm
's	I-Algorithm
algorithm	I-Algorithm
can	O
solve	O
these	O
problems	O
exponentially	O
faster	O
than	O
the	O
best	O
known	O
algorithms	O
for	O
conventional	O
computers	O
.	O
</s>
<s>
Post-quantum	O
cryptography	O
is	O
the	O
subfield	O
of	O
cryptography	O
that	O
aims	O
to	O
replace	O
algorithms	O
broken	O
with	O
new	O
ones	O
that	O
are	O
believed	O
hard	O
to	O
break	O
even	O
for	O
a	O
quantum	B-Architecture
computer	I-Architecture
.	O
</s>
<s>
The	O
main	O
families	O
of	O
post-quantum	O
alternatives	O
to	O
factoring	O
and	O
discrete	O
logarithm	O
include	O
lattice-based	O
cryptography	O
,	O
multivariate	O
cryptography	O
,	O
hash-based	O
cryptography	O
and	O
code-based	O
cryptography	O
.	O
</s>
<s>
System	O
evolution	O
and	O
crypto-agility	B-Algorithm
are	O
not	O
the	O
same	O
.	O
</s>
<s>
Crypto-agility	B-Algorithm
is	O
related	O
instead	O
to	O
computing	O
infrastructure	O
and	O
requires	O
consideration	O
by	O
security	O
experts	O
,	O
system	O
designers	O
and	O
application	O
developers	O
.	O
</s>
<s>
Best	O
practices	O
about	O
dealing	O
with	O
crypto-agility	B-Algorithm
include	O
:	O
</s>
<s>
Crypto-agility	B-Algorithm
requirements	O
must	O
be	O
disseminated	O
to	O
all	O
hardware	O
,	O
software	O
and	O
service	O
suppliers	O
,	O
who	O
must	O
comply	O
on	O
a	O
timely	O
basis	O
;	O
suppliers	O
who	O
cannot	O
address	O
these	O
requirements	O
must	O
be	O
replaced	O
.	O
</s>
<s>
Symmetric-key	B-Algorithm
algorithm	I-Algorithm
should	O
be	O
flexible	O
in	O
their	O
key	O
lengths	O
.	O
</s>
<s>
Hash	B-Error_Name
algorithms	I-Error_Name
should	O
support	O
different	O
lengths	O
of	O
outputs	O
.	O
</s>
