<s>
S-63	B-Application
is	O
an	O
International	O
Hydrographic	O
Organization	O
(	O
IHO	O
)	O
standard	O
for	O
encrypting	O
,	O
securing	O
and	O
compressing	O
electronic	B-Application
navigational	I-Application
chart	I-Application
(	O
ENC	O
)	O
data	O
.	O
</s>
<s>
The	O
S-63	B-Application
standard	O
secures	O
data	O
by	O
encrypting	O
the	O
basic	O
transfer	O
database	O
using	O
the	O
Blowfish	B-Algorithm
algorithm	O
,	O
SHA-1-hashing	O
the	O
data	O
based	O
on	O
a	O
random	O
key	O
and	O
adding	O
a	O
CRC32	O
check	O
.	O
</s>
<s>
Compression	O
is	O
achieved	O
by	O
applying	O
the	O
standard	O
ZIP	B-General_Concept
(	O
file	O
format	O
)	O
algorithm	O
to	O
the	O
base	O
and	O
update	O
ENC	O
files	O
,	O
before	O
encryption	O
.	O
</s>
