<s>
Blocknots	B-Algorithm
were	O
random	O
sequences	O
of	O
numbers	O
contained	O
in	O
a	O
book	O
and	O
organized	O
by	O
numbered	O
rows	O
and	O
columns	O
and	O
were	O
used	O
as	O
additives	O
in	O
the	O
recyphering	O
of	O
Soviet	O
Union	O
codes	O
,	O
during	O
World	O
War	O
II	O
.	O
</s>
<s>
The	O
Blocknot	B-Algorithm
consisted	O
of	O
fifty	O
sheets	O
of	O
5-figure	O
random	O
additive	O
,	O
100	O
additive	O
groups	O
to	O
a	O
sheet	O
.	O
</s>
<s>
No	O
sheet	O
was	O
used	O
more	O
than	O
once	O
,	O
thus	O
the	O
blocknots	B-Algorithm
were	O
in	O
effect	O
a	O
form	O
of	O
one-time	B-Algorithm
pad	I-Algorithm
.	O
</s>
<s>
The	O
Soviet	O
Unions	O
highest	O
grade	O
ciphers	O
that	O
were	O
used	O
in	O
the	O
East	O
,	O
were	O
the	O
5-figure	O
codebook	O
enciphered	O
with	O
the	O
Blocknot	B-Algorithm
book	O
,	O
and	O
were	O
generally	O
considered	O
unbreakable	O
.	O
</s>
<s>
Blocknots	B-Algorithm
were	O
distributed	O
centrally	O
from	O
an	O
office	O
in	O
Moscow	O
.	O
</s>
<s>
Every	O
Blocknot	B-Algorithm
contained	O
5-figure	O
groups	O
in	O
a	O
number	O
of	O
sheets	O
,	O
for	O
the	O
enciphering	O
of	O
5-figure	O
messages	O
.	O
</s>
<s>
The	O
General	O
in	O
which	O
each	O
page	O
of	O
the	O
Blocknot	B-Algorithm
was	O
valid	O
for	O
one	O
day	O
.	O
</s>
<s>
In	O
5-figure	O
messages	O
,	O
the	O
blocknot	B-Algorithm
was	O
one	O
of	O
the	O
first	O
10	O
Groups	O
in	O
the	O
message	O
.	O
</s>
<s>
Blocknot	B-Algorithm
used	O
for	O
passing	O
on	O
traffic	O
.	O
</s>
<s>
The	O
distribution	O
of	O
Blocknots	B-Algorithm
was	O
carried	O
out	O
centrally	O
from	O
Moscow	O
to	O
Army	O
Groups	O
then	O
to	O
Armies	O
.	O
</s>
<s>
Occasionally	O
the	O
same	O
blocknot	B-Algorithm
was	O
distributed	O
to	O
two	O
units	O
on	O
different	O
parts	O
of	O
the	O
front	O
,	O
which	O
enabled	O
Depth	O
to	O
be	O
established	O
.	O
</s>
<s>
Records	O
of	O
all	O
Blocknots	B-Algorithm
used	O
were	O
kept	O
in	O
Berlin	O
and	O
when	O
a	O
repeat	O
was	O
noticed	O
a	O
BLOCKNOT	B-Algorithm
ANGEBOT	O
message	O
was	O
sent	O
out	O
to	O
all	O
German	O
Signals	O
units	O
,	O
to	O
indicate	O
that	O
it	O
may	O
have	O
been	O
possible	O
to	O
break	O
the	O
code	O
using	O
it	O
.	O
</s>
<s>
One	O
indicator	O
was	O
the	O
Blocknot	B-Algorithm
number	O
and	O
the	O
consisted	O
of	O
two	O
random	O
figures	O
,	O
the	O
figure	O
representing	O
the	O
type	O
,	O
and	O
the	O
remaining	O
two	O
,	O
the	O
page	O
of	O
the	O
Blocknot	B-Algorithm
being	O
used	O
.	O
</s>
<s>
Blocknots	B-Algorithm
were	O
tracked	O
in	O
a	O
card	O
index	O
,	O
that	O
was	O
maintained	O
by	O
the	O
Signal	O
Intelligence	O
Evaluation	O
Centre	O
(	O
NAAS	O
)	O
.	O
</s>
<s>
Search	O
card	O
index	O
,	O
contained	O
all	O
blocknots	B-Algorithm
and	O
chi-numbers	O
whether	O
or	O
not	O
they	O
were	O
known	O
.	O
</s>
<s>
The	O
Blocknots	B-Algorithm
were	O
also	O
used	O
in	O
the	O
Stationary	O
Intercept	O
Company	O
(	O
Feste	O
)	O
,	O
the	O
military	O
unit	O
that	O
were	O
designed	O
to	O
work	O
at	O
a	O
lower	O
level	O
to	O
the	O
NAAS	O
,	O
at	O
the	O
Army	O
level	O
and	O
were	O
semi-motorized	O
,	O
and	O
closer	O
to	O
the	O
front	O
.	O
</s>
<s>
The	O
Feste	O
used	O
the	O
Blocknot	B-Algorithm
value	O
along	O
with	O
several	O
other	O
parameters	O
to	O
build	O
a	O
network	O
diagram	O
.	O
</s>
<s>
Marquart	O
was	O
assigned	O
the	O
study	O
of	O
the	O
Soviet	O
Union	O
Blocknot	B-Algorithm
traffic	O
.	O
</s>
<s>
All	O
the	O
counts	O
which	O
they	O
made	O
,	O
however	O
,	O
failed	O
to	O
reveal	O
any	O
non-random	O
characteristics	O
in	O
the	O
design	O
of	O
the	O
tables	O
,	O
and	O
while	O
they	O
thought	O
the	O
Blocknots	B-Algorithm
must	O
have	O
been	O
generated	O
by	O
machine	O
,	O
they	O
were	O
never	O
able	O
to	O
draw	O
any	O
concrete	O
deductions	O
as	O
a	O
result	O
of	O
their	O
research	O
.	O
</s>
<s>
The	O
Soviet	O
3rd	O
Guard	O
Tank	O
Army	O
transmits	O
a	O
5-figure	O
message	O
with	O
the	O
Blocknot	B-Algorithm
of	O
37581	O
(	O
one	O
of	O
the	O
first	O
10	O
groups	O
in	O
the	O
message	O
)	O
.	O
</s>
<s>
After	O
a	O
few	O
days	O
,	O
an	O
unidentified	O
net	O
with	O
the	O
Blocknot	B-Algorithm
37588	O
is	O
picked	O
up	O
.	O
</s>
<s>
The	O
missing	O
Blocknots	B-Algorithm
84-87	O
were	O
presumably	O
used	O
in	O
telegraphic	O
,	O
telephonic	O
or	O
courier	O
communications	O
.	O
</s>
<s>
The	O
Chi	O
number	O
provides	O
confirmation	O
of	O
the	O
first	O
assumption	O
,	O
based	O
on	O
proximity	O
of	O
blocknots	B-Algorithm
in	O
most	O
cases	O
.	O
</s>
