Industrial and military cryptography should follow the same basic rules, but what does make them different is:

  • Higher key length, protocols unknown to the civilian world, and perhaps unique methods of transferring media

Are there other fundamental differences that make military encryption safer?

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – e-sushi Sep 23 '18 at 3:29

10 Answers 10


Clearly there is a difference between military grade encryption and civilian encryption. One of them is for use strictly by the military. That's probably the main difference, although no one herein is qualified to answer definitively.

There is a common list floating on the Interweb showing the alleged contents of Suite A. Algorithms include:-



  • CDL 1

  • CDL 2

  • FFC










Two alternatives face us. One, this is just a joke list or a feint put about by the security services as a means of disinformation. It's what I'd do. Two, it has some elements of truth. The latter seems more convincing in that it ties in with other independent evidence. Although the best lies are those that are partly true.

Looking at BATTON, FIREFLY and SAVILLE, they are old. SAVILLE is from the 1960s. It is unlikely to be faster/more secure/better than AES or SHA3. There is speculation that it uses a 120 bit key. The KYK-13 Electronic Transfer Device certainly exists as I've seen one. That's decades old too. It's like a military USB key that doesn't fit on a necklace.

FIREFLY was used in STU-III secure phones from the 1980s. Newer ones use civilian Diffie-Hellman key exchange.

BATON may be an unbalanced Feistel network that only runs faster than a Dodo Clipper chip from the 1990s. Hardly impressive.

Reiterating, this could all be balderdash put about to keep us guessing. However it has the smell of truth when you consider the military obsession with secrecy. And a very good reason to keep it all secret would be that it's mainly rubbish by current civilian standards. Look at Britain's nuclear deterrent powered by Windows for Submarines. If suite A has really been upgraded, it's probably the best kept secret in the world. And given that people like Snowden / Assange exist, and that many secrets have been released to the public, this seems unlikely.

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – e-sushi Sep 23 '18 at 3:28
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    $\begingroup$ you forgot rot13 - military grade encryption used by Julius Caesar around 100BC (a bigtime Roman military general) $\endgroup$ – hanshenrik Sep 23 '18 at 6:38
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    $\begingroup$ "it's mainly rubbish by current civilian standards" - Which can be strategically useful. As in, fake some seemingly high-value intel, encrypt it with one of your weaker algorithms, and then broadcast it somewhere that you know it will be intercepted and decoded by your enemy. Then wait for them to take the bait and fall into your trap. $\endgroup$ – aroth Sep 24 '18 at 14:27
  • $\begingroup$ The source of much of the list in that answer is this archived General Dynamics document. $\endgroup$ – fgrieu Sep 26 '18 at 6:31

There’s no difference except for marketing. Neither of the terms has a meaningful technical definition on which a substantial share of experts in the field can agree.

Historically there was a difference in permissible key length due to U. S. export restrictions but those stopped a long time ago except for a few countries that are under broader embargo (e. g. North Korea, Iran, Syria).

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – e-sushi Sep 23 '18 at 3:29

The main difference between industrial and military cryptography is the key-length, or difficulty in decryption in general.

Everybody should rely on Kerckhoffs's principle, which states:

A cryptosystem should be secure even if everything about the system, except the key, is public knowledge.

You should never rely on secret algorithms because it would need only one person (i.e. a spy) who can reveal the secret algorithm to the enemy.

In the past, the military often used Steganography to communicate in secret, but as far as we know this trend has come to an end by using reliable cryptography.

One option for today's military security may also be secure channels because they can establish a separate infrastructure that isn't available to the public, but even this isn't used in a large scale.


The term "military grade encryption" is often just thrown around in movies, but usually, there's no difference because in the end, everyone relies on Kerckhoffs's principle by using known cryptosystems with large keys.

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    $\begingroup$ I had to -1 for the first sentence, because it implies something labeled "military grade" encryption will be more resistant to brute force/cryptanalysis or that "regular" encryption is somehow weaker. (impossible is impossible, there's no such thing as "more impossible"). Also, "difficulty in decryption" would be a very poor feature to have, considering that decryption is something almost always performed by an honest party. If CTR mode is being used, then the decryption process is identical to the encryption process. $\endgroup$ – Ella Rose Sep 20 '18 at 14:06
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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – e-sushi Sep 23 '18 at 3:32
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    $\begingroup$ There is a difference. The industrial cryptography can be investigated by far more people than the military. $\endgroup$ – kelalaka Sep 24 '18 at 8:57

As having some experience on military crypto, as Aleksander Rassasse said, everybody relies on Kerckhoffs's principle. Yes, everybody relies on.

However, there are some differences. Militaries still think that even we relay on the Kerckhoffs's principle, as a security measure, we will not release our cryptographic algorithms, Error-Correcting Codes, protocols, key distribution systems, etc, and the crypto devices to 3rd party investigation.

Instead, closed communities try to imitate the open community. That is; setting up groups that have different aims as algorithm designer group and analyzer group. Former group design and the latter requires some time to analyze. The reason is simple; the path of wisdom is unique.

This is completely personal taught; (Also, I believe that NSA or other agencies, try to outsource some of their problems so that they can use the result in their problem)

As a consequence of this kind of restrictions, fewer minds analyze and see the problems. Whereas, in industrial, at least somebody can buy the device and reverse engineer it, as in A5/1, and finally show that it is breakable.

Military actually benefit from these restrictions. As an example, when you listen over a radio channel, one cannot distinguish whether the signal just an open message+ECC or message+zip+ECC+encryption, etc.

One interesting example of fewer mind analyze is the SIMON cipher by NSA. Now, it is almost broken.

One interesting example is in OpenSSL, Dual_EC_DRBG. This is missed 7 years from the open community.

Conclusion; let them play their games, and let play ours.

I was once part of a closed one.

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    $\begingroup$ how exactly is Simon almost broken? The best attack I have seen only gets about 24 rounds in with significant time and data requirements $\endgroup$ – Richie Frame Sep 27 '18 at 2:46
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    $\begingroup$ eprint.iacr.org/2018/699, almost broken comes from Daniel J. Bernstein's tweet. The attack is for 27 round. $\endgroup$ – kelalaka Sep 27 '18 at 7:49
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    $\begingroup$ I had not seen that, only the 24 rd integral, although it still requires $2^{63}$ time for a 64-bit key, along with over a million gigabytes of working memory. Even if they could extent to 32 rounds, I would not consider that a practical break (like the AES related key attacks) $\endgroup$ – Richie Frame Sep 27 '18 at 23:54

The main differences would be that the underlying mechanisms in which Suite A crypto functions is not known to the general civilian population. Whereas the mechanics and algorithms used in 'industrial' crypto are mostly available for anyone to inspect. For example check out GNU libgcrypt Another difference would be that one cipher would be guaranteed to not be decrypted.


The difference between military and civilian anything is that the military version must be usable by a poorly educated youngster who is stuck in a ditch with gunfire around him. On the other hand, military stuff is used by people who have been drilled to follow the rules exactly.

So military encryption must be designed to be set up and used easily by someone who is not incredibly smart but drilled to follow clear instructions. And the military can and will protect their physical hardware with men with guns, which protects them from certain attacks.

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – e-sushi Sep 23 '18 at 3:31

Auguste Kerckhoffs said it all in his La Cryptographie militaire (1881). David Kahn, speaking of Kerckhoffs in The Codebreakers, says that he:

...made the requirements that have come to be demanded of systems of military cryptography, requirements such as simplicity, reliability, rapidity, and so on. This clear recognition of the new order constitutes Kerckhoffs' first great contribution to cryptology.

Kerckhoffs revolutionized military telegraphy and set it apart from the rest.

Much more recently, Bruce Schneier made an interesting distinction between academic and military cryptography--and their courses of development:

"Academic cryptography is mostly based on Feistel's work in the mid-1970s at IBM: SP-networks and Feistel networks. Military cryptography started with rotor machines, and then generalized into shift registers... I find it fascinating that the two different design paths are converging." [1]

What Mr. Schneier meant was that modern military cryptography developed out of rotor devices such as the Hagelin machines (for example, the M-209) which were replacements for earlier systems such as the M-94 cylinder. This cylinder and the M-138 strip ciphers saw extensive use during the 1930's and all of World War II, but they are seldom discussed today. Incredibly important traffic-- that of the Manhattan Project-- was encrypted with the M-94. What is it the distinguishing feature of these systems? They are portable and lightweight.

Being lightweight was, and still is, extremely important for military cryptographic systems. The German Schlüsselgerät 41 (SG41) was superior to Engima, but it weighed about 30 pounds, and was therefore too heavy to deploy for frontline use.

Modern military encryption often focuses on radio and satellite communications, but it depends on what country one is talking about. For some it might just be radio. Encrypted military radio systems tend to send traffic via some method of spread-spectrum transmission such as frequency hopping. This is sometimes done to prevent jamming (denial).

Authentication is extremely important; metacontent is too. Plaintexts are usually highly structured, and acronyms are very common. The best encryption a country has in stock will probably be used for command and control by senior leaders. A lot is at stake.

The adversarial nature of cryptography, its essence, is clearly seen in military information security.

Compromise can have immediate catastrophic results. Military encryption is often done as half of a skill set, the other half being cryptanalysis. The viewpoint of the attacker can be developed, which is precious. In very general terms, military encryption today is surprisingly aware of the history of cryptography because of what one might encounter or need to use downrange--most of today's conflicts are asymmetrical. Classical cryptography is still being used by certain groups.

Military encryption usually takes place in a wider security context that is very substantial and includes strong physical security, careful key management, and counter-intelligence.

If we include the encryption methods of insurgents, paramilitaries, and other such actors under military encryption, then we see a reliance on classical methods such as code books. Serious people such as NVA Special Forces were known to use one-time pads and HF radio. In military matters what is often needed for immediate success is just something simple and dependable--and that applies to encryption too. Forward secrecy may not always be the biggest concern, especially at the squad/platoon/company levels, and it has to be fast and simple (not a VIC cipher, for example).

  • $\begingroup$ Finding a weakness in military-grade encryption it will cause a disaster like the Enigma machine, it is vital for every country to have secure communication in the military, it is always possible to capture radio transmission in the field and analyzing it to find vital result, is it method like FHSS or etc helping in this issue or it is not important if data is being captured ? $\endgroup$ – R1w Jul 16 '19 at 15:41
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    $\begingroup$ @R1w At the squad or platoon levels, the value of information may be high, but for a very short time. If you were to break it six months later, it might not mean much at all. $\endgroup$ – Patriot Jul 16 '19 at 15:47
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    $\begingroup$ An interesting point to all of this is that Allied encryption efforts were actually shoddy at the beginning of World War II, and both the Japanese and the Germans enjoyed significant success against the Allies. However, the cryptographic tide would turn. $\endgroup$ – Patriot Aug 8 '19 at 13:31

While the military may have a hidden encryption protocol it really wouldn't make much sense to develop one, an open source system has the advantages that:

A)It already has implementations that you can base yours off of, making it cheaper to develop.
B)It has been tested by hundreds or even thousands of people, think how many companies and organizations have an interest in AES being secure and would check that it is, especially when it was in it's infancy.
C)You don't need to pay someone to develop it (cost is always a consideration).

While it is possible that a government has found some security exploit within modern encryption and developed one without that flaw it is likely that any exploit within the algorithm would have been found and published by now.
As mentioned by Aleksander Rassasse they likely just use large keys. The main advantage the military have is their experience in physical security (someone stealing the keys is always a risk) but no software can provide that.


Military apply the concept “security through obscurity” and the key length is important but it is not always the case, for example:

  1. Chiasmus cipher (secret German cipher leaked by reverse engineering) used 64-bit plaintext ,160-bit key length and ECB mode.
  2. Red pike block cipher uses  64-bit block size and 64-bit key length (leaked on Cypherpunk)

Industry tend to use standards mainly AES (highly respected as a strong cipher and received many public analysis) especially when cryptography is not their core business.


Ignoring marketing material that throws terms like "military grade" around without any real meaning...

The stuff the military are allowed to use is stronger than the stuff allowed to be sold commercially, and commercially there are restrictions on who you can sell different strengths of encryption to (EG only "friends" of the USA can buy equipment with certain grades of crypto in).

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    $\begingroup$ While the "stronger stuff allowed" may be true in some jurisdictions, this does not at all imply that everything "military grade" will be "stronger stuff". $\endgroup$ – rackandboneman Sep 21 '18 at 16:00

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