“Some are worried it signals that North Korean might be planning some type of operation, alerting its spies by sending the coded broadcast. But for that to be true, North Korean agents would have had to have been listening at the right time to take down the message, and how would they have known it was coming?
Numbers haven’t been broadcast for 16 years, so have agents really spent the last decade and a half listening just in case something came across? It is possible they could have been alerted that such a message was about to be broadcast, but then when why not send the message contents over whatever communications channel was used for such an alert?”
Martyn Williams — 38 North
July 23 2016 — The broadcast on July 15 2016 was the first number sequence aired by Pyongyang in over 16 years. Follow us on Twitter: @INTEL_TODAY
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UPDATE (July 24 2021) — Quick note about KRYPTOS K4
In my last update, I suggested that the method described in this post may have been used to encrypt the last part of the CIA Kryptos?
Of course, that would make sense only if the information needed to decode K4 was provided in the previous sections. Or else, K4 could not be deciphered at all!
However, it has been reported that Jim Sanborn was asked if K4 can be solved without solving K1-K3 first? And his answer was: “Yes, but K5 cannot be solved without K4.”
Therefore, I no longer believe that this method was used to encrypt K4. And no one knows what K5 is anyway? K4 remains a complete mystery!
UPDATE (July 23 2020) — What do the numbers mean? How does one decode such messages? That is actually quite simple.
[Perhaps, this method was used to encrypt the last part of the CIA Kryptos?]
The agent is equipped with a key and a ‘book’ of cypher pads. Then, he receives a message such as this one:
64056
92478
14417
23755
The first 5 digits tells him which pad to use. So in this case: ‘pad’ 64056.
64056
34589
56780
06653
…
Now, the agent must subtract the message from the pad.
64056 34589 56780 06653
64056 92478 14417 23755
The result is:
00000 42111 42373 83908
Now the agent has the real, but coded, message. [Please, note that only a person having access to this unique cypher pad can access the message.]
Now, how to decode the message? Here is the ‘common’ key provided to the agent.
According to the table of the key, the digits 2, 3, and 4 are matched with the digits following them. So the message actually reads:
00000 42 111 42 37 38 39 0 8
which the agent decodes as:
00000 42 111 42 37 38 39 0 8
00000 Y 111 Y P R S Z E
Now, the numbers or names are repeated three times and are clasped in between two Y.
So the message is :
1 PRSZE
Which a person familiar with the language (PROSZE means Please in Polish) readily understands as : “N°1 , Please.”
NB: This is actually a real common key code used by the BND (and thus the Americans) to communicate with their (non-German speaking) agents in Poland during the cold war.
Notice a ‘mistake’ in the key. The letter ‘U’ is missing. This is probably a typing mistake. They were not at all uncommon.
END of UPDATE
The 12-minute broadcast began shortly after midnight on 15 July 2016, with a female voice saying:
“I will give review work to No. 27 exploration agents.”
The announcer then read:
“On page 459 number 35, on page 913 number 55, on page 135 number 86, on page 257 number 2,” and so on.
The technique described above is informally known as ‘numbers stations’, and was extensively used by both Western and communist countries during the Cold War to send operational instructions to their intelligence personnel stationed abroad.
“Armed with a shortwave radio, an intelligence officer would turn to the right frequency on a pre-determined date and time, write down the numbers read out and proceed to decrypt them using a ‘number pad’, a tiny book that contained the key to deciphering the secret message aired on the radio.
But the era of the Internet, mobile phones and microwave communications has caused the demise of ‘numbers stations’.
The latter are rarely heard nowadays, though a number of nations, including Cuba, South Korea and Israel, are believed to still use them.” [Joseph Fitsanakis – IntelNews]
Yonhap quoted an unnamed South Korean government source as saying that last Friday’s broadcast was the first number sequence aired by Pyongyang in over 16 years. But a similar two-minute broadcast took place on 24 June 2019.
In any case, Seoul should be worried about “possible provocations” that may be planned by North Korean spies living secretly in the south.
Then again, it may just be psychological warfare.
So why the sudden restart of broadcasts?
Martyn Williams has published a good piece on the 38 North Website: Cold War Communications: The Two Koreas Resume Coded Radio Broadcasts.
Some are worried it signals that North Korean might be planning some type of operation, alerting its spies by sending the coded broadcast. But for that to be true, North Korean agents would have had to have been listening at the right time to take down the message, and how would they have known it was coming?
Numbers haven’t been broadcast for 16 years, so have agents really spent the last decade and a half listening just in case something came across? It is possible they could have been alerted that such a message was about to be broadcast, but then when why not send the message contents over whatever communications channel was used for such an alert?
Had this been a real broadcast, interpreting the message would have relied on code books that are probably years out of date, making the whole thing all the more unlikely.
There is also a possibility the broadcast really was some sort of remote mathematics course, but that seems equally unlikely given its sudden and unexplained start.
Perhaps the most credible theory says that North Korea is trying to cause a bit of panic and confusion in Seoul. If that’s true, then mission accomplished—at least for a day or two.
But the fuss in Seoul about the return of North Korean numbers on the airwave misses an important point: South Korea itself resumed its own numbers broadcasts back in February, although the National Intelligence Service isn’t as keen to talk about those.
South Korea has a much richer recent history of using numbers stations than its northern neighbor. After all, while the Internet and digital communications have made the radio stations obsolete in the rest of the world, North Korea stands alone in the almost complete absence of technological progress. So radio remains the best and safest way for South Korea to contact its agents in the north.
South Korea’s broadcasts ran for years with the same format: a Korean song and numbers: “Attention number 521, attention number 521, please receive a telegram…”
Here’s one such broadcast:
Popular culture
The Numbers Station is a 2013 action thriller film, starring John Cusack and Malin Akerman, about a burned-out CIA black ops agent assigned to protect the code operator at a secret American numbers station somewhere in the British countryside.
Cuban Numbers Stations
In the age of Internet, one would think that “Numbers Stations” are things of the past. One would be wrong.
For instance, Cuba was using them ‘recently’ to communicate to its agents inside the United States, as demonstrated by the Anna Montes’ story.
RELATED POST: The Queen of Cuba: The two stories of Ana Montes
Ana Belén Montes (born February 28, 1957) is a former American senior analyst at the Defense Intelligence Agency in the United States and convicted spy.
On September 21, 2001, she was arrested and subsequently charged with conspiracy to commit espionage for the government of Cuba.
Montes eventually pleaded guilty to spying and in October 2002, was sentenced to a 25-year prison term followed by five years’ probation.
“Montes communicated with the Cuban Intelligence Service through encrypted messages and received her instructions through shortwave encrypted transmissions from Cuba.
In addition, Montes communicated by coded numeric pager messages with the Cuban Intelligence Service by public telephones located in the District of Columbia and Maryland.” [US Federal prosecutors]
North Korean Numbers Station V15 ‘Radio Pyongyang’ 6400kHz
Transmitting via an international broadcaster, Pyongyang Broadcasting Station 6400khz.
After the transmission the station returned to its regular programming.
REFERENCES
North Korea is criticised by South Korea for ‘spy broadcasts’ BBC 20 July 2016
North Korea resumes Cold-War-era radio broadcasts for its spies abroad IntelNews
The spooky world of the ‘numbers stations’
North Korea’s radio broadcast of string of mysterious numbers is possible code The Guardian 19 July 216
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Radio Pyongyang resurrects ‘NUMBERS STATION’
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