The Security Vulnerabilities of Message Interoperability

Jenny Blessing and Ross Anderson have evaluated the security of systems designed to allow the various Internet messaging platforms to interoperate with each other:

The Digital Markets Act ruled that users on different platforms should be able to exchange messages with each other. This opens up a real Pandora’s box. How will the networks manage keys, authenticate users, and moderate content? How much metadata will have to be shared, and how?

In our latest paper, One Protocol to Rule Them All? On Securing Interoperable Messaging, we explore the security tensions, the conflicts of interest, the usability traps, and the likely consequences for individual and institutional behaviour.

Interoperability will vastly increase the attack surface at every level in the stack ­ from the cryptography up through usability to commercial incentives and the opportunities for government interference.

It’s a good idea in theory, but will likely result in the overall security being the worst of each platform’s security.

Posted on March 29, 2023 at 7:03 AM30 Comments


Andy March 29, 2023 10:07 AM

A weakened security is what the governments want anyway, don’t they? And now they’ll credit themselves for helping the consumer

Clive Robinson March 29, 2023 11:35 AM

@ Bruce, ALL,

Re : Is a message defined by content?

As Prof Ross Anderson notes,

“The Digital Markets Act ruled that users on different platforms should be able to exchange messages with each other.”

That is ambiguous because a “message” is not defined.

A message at it’s lowest level just a communication, that is it does not have to have any content in it.

Such messages are seen in “keep alives” and “anti-brownout” systems, the actual transfer of the communication is the message, not anything the message might contain.

At the next level up a message can be saod to consist of a “Bag of Bits”(BoB) with or without any meya data that might make it understandable in some way. In this respect it is now like a file contents, but without any file meta-information.

And so on up, each layer defined by a new standard and meta-data and meta-meta-data.

When you think about it eqch layer can be viewed as a Shannon Channel, and as such can be within another Shannon Channel and contain further Shannon Channels. So in effect just like a Russian Matryoshka doll.

Leaving the question,

“Which doll is the doll? And how do you decide?”.

In short the law, it’s self to work in one way has to fail in a different way.

This is a problem that arises when you treat “information objects” as though they are “physical objects” they are not the same, not even close.

So any system that can connect to another system both passes and fails the same legal test… And whilst it can always be said “It will fail” the test, you can never with any ceryainty say “It will pass the test” because that is a logical imposibility…

Not that this appears to concern the legislators or legal bretherin. The Legislators claim they have acted, and the legal bretherin just see endless billable hours to argue…

Clive Robinson March 29, 2023 11:59 AM

@ ALL,

Re : EU DMA Perspective,

For those who need to considet the EU DMA in a different way, “The Conversation” gave a perspective view,

Importantly note the failure of current “take over” legislation brought in back in the “Bricks and Mortar Business Days”.

Likewise how online businesses in particular could simply re-form themselves around the legislation to negate it’s effectiveness.

Oh and it also has some quite useful links on the subject…

Winter March 29, 2023 12:01 PM


That is ambiguous because a “message” is not defined.

I think judges will have absolutely no problem in deciding this: If A sends a message (text/speech/picture) to B, then be must receive the text/speech/picture in a legible form. Period.

iAPX March 29, 2023 12:09 PM


I could not wait to see that in action, with the receiver using a dumb phone and thus limited to SMS…

RealFakeNews March 29, 2023 12:42 PM

Making them interoperable is easy. The catch is where is the plaintext handled?

This is just another way to break message security.

As always, seperate the security from the transmission system.

Renee W March 29, 2023 12:57 PM

@ Clive Robinson,

That is ambiguous because a “message” is not defined.

I find the use of the word “should” a bigger problem. Laws are generally written as “shall” and “shall not”, not “should” (which almost contradicts the idea of a “rule”). It seems to just be a bad summary, though. The terms “mandate” and “requires” are used at the end of page 1, with the caveat that only “the largest” platforms are affected.

Here’s the actual regulation. “The gatekeeper shall make at least the following basic functionalities referred to in paragraph 1 interoperable where the gatekeeper itself provides those functionalities to its own end users: … end-to-end text messaging … sharing of images, voice messages, videos and other attached files”. “[W]ithin 2 years…: end-to-end text messaging within groups … sharing of images, voice messages, videos and other attached files in end-to-end communication between a group chat and an individual end user”. “[W]ithin 4 years…: end-to-end voice[/video] calls [between users, and between groups and individuals]”.

It also says: “The level of security, including the end-to-end encryption, where applicable, that the gatekeeper provides to its own end users shall be preserved across the interoperable services”—which the paper quotes and says “raises as many questions as it answers”, because it may be impossible: for example, what if some service without perfect forward secrecy wishes to interoperate with a service that has this feature? That might just be a mistake, a shibboleth indicating that “security people” were not involved in the drafting. A sane interpretation would be that communication between a user on service A and one on service B would, at minimum, have the security of either A-to-A or B-to-B communication. Which may still be difficult, and still mean that adding one “less secure” user to a group chat degrades the security of the whole thing. On the other hand, it could go the other way, with services having to be made more secure before being allowed to interoperate. That would be a good thing overall; but it goes against the EU’s own ideas of message filtering, lawful access, etc., which suggests it may not be the intent.

Ray Dillinger March 29, 2023 1:26 PM

The Digital Markets Act is the latest in a long line of legal demands for things which, somehow, are never quite satisfactory until security is weakened just enough to covertly eavesdrop on.

Interoperating is going to require the platforms either having the plaintext, or using some central repository or server for keys, and either way it’s going to be something that can be routinely harvested.

Or if it manages not to be something that can be routinely harvested there’ll be some other afterthought of a requirement that refines the result until it can be.

modem phonemes March 29, 2023 3:28 PM

All messages shall go through the big secur-y-go-round in the sky (cloud).

In this way the N(N-1)/2 converter explosion is avoided.

vas pup March 29, 2023 5:25 PM

The danger for privacy is always exists when xref against different private DBases, platforms as well as private and government data bases and within government against data bases assigned for separate agencies and different purposes.

Closely related to te subject:

Clearview AI used nearly 1m times by US police, it tells the BBC

“Facial recognition firm Clearview has run nearly a million searches for US police, its founder has told the BBC.

CEO Hoan Ton-That also revealed Clearview now has 30bn images scraped from platforms such as Facebook, taken without users’ permissions.

The company has been repeatedly fined millions of dollars in Europe and Australia for breaches of privacy.

Critics argue that the police’s use of Clearview puts everyone into a “perpetual police line-up”.

“Whenever they have a photo of a suspect, they will compare it to your face,” says Matthew Guariglia from the Electronic Frontier Foundation says. “It’s far too invasive.”

Clearview’s system allows a law enforcement customer to upload a photo of a face and find matches in a database of billions of images it has collected.

It then provides links to where matching images appear online. It is considered one of the most powerful and accurate facial recognition companies in the world.

The company is banned from selling its services to most US companies, after the American Civil Liberties Union (ACLU) took Clearview AI to court in Illinois for breaking privacy law.

But there is an exemption for police, and Mr Ton-That says his software is used by hundreds of police forces across the US.

Police in the US do not routinely reveal whether they use the software, and it is banned in several US cities including Portland, San Francisco and Seattle.

The use of facial recognition by the police is often sold to the public as only being used for serious or violent crimes.

In a rare interview with law enforcement about the effectiveness of Clearview, Miami Police said they used the software for every type of crime, from murders to shoplifting.

==>Mr Aguilar says Miami police treats facial recognition like a tip. “We don’t make an arrest because an algorithm tells us to,” he says. “We either put that name in a photographic line-up or we go about solving the case through traditional means.” [agree 100%].

Mr Ton-That says he has recently given Clearview’s system to defence lawyers in specific cases. He believes that both prosecutors and defenders should have the same access to the technology.

Last year, Andrew Conlyn from Fort Myers, Florida, had charges against him dropped after Clearview was used to find a crucial witness.

Mr Conlyn was the passenger in a friend’s car in March 2017 when it crashed into palm trees at high speed.

The driver was ejected from the car and killed. A passer-by pulled Mr Conlyn from the wreckage, but left without making a statement.

Although Mr Conlyn said he was the passenger, police suspected he had been driving and he he was charged with vehicular homicide.

His lawyers had an image of the passer-by from police body cam footage. Just before his trial, Mr Ton-That allowed Clearview to be used in the case.

“This AI popped him up in like, three to five seconds,” Mr Conlyn’s defense lawyer, Christopher O’Brien, told the BBC. “It was phenomenal.”

The witness, Vince Ramirez, made a statement that he had taken Mr Conlyn out of the passenger’s seat. Shortly after, the charges were dropped.”

SpaceLifeForm March 29, 2023 5:32 PM

@ iAPX

I must be misunderstanding your point.

You can not send an SMS to a POTS line.

lurker March 29, 2023 8:20 PM

@SpaceLifeForm, iAPX, Winter

For many years (certainly before the advent of “feature” phones) “dumb” (cell) phones have been able to send and receive TXT, aka SMS.

The trick is whether the judge can get both A and B to stand up in court and say, yes they fully understood the capability of each other’s phone.

ResearcherZero March 30, 2023 2:30 AM

“A blueprint for repression around the world.”

The European Parliament is debating a proposal that, if it passes, could be disastrous for privacy worldwide. Every message, photo, or hosted file could be scanned, with the results sent to government agencies.

Chat Control Bill

On 11 May 2022 the European Commission presented a proposal which would make chat control searching mandatory for all e-mail and messenger providers and would even apply to so far securely end-to-end encrypted communication services.

The European Data Protection Board: “Raises serious concerns of the fundamental rights to privacy and the protection of personal data”

State powers to control and surveil all users’ communications and information.

There is no backdoor to encryption that won’t be exploited by bad actors, including cyber criminals, rogue employees, domestic abusers, and authoritarian governments.

Clause 110 (Online Safety Bill)

ResearcherZero March 30, 2023 2:31 AM

“When the United States repealed net neutrality, they created an environment in which it would be easy, from a technical standpoint, for internet service providers to interfere with or block internet traffic. The architecture for greater censorship is already in place and we should all be concerned about heading down a slippery slope.”

“Remote censorship measurements of a certain country can be affected by policies in a different country on the path, which has significant implications for censorship measurement research. In Belarus, our measurements found that devices are deployed closer to the user, and they are deployed off the path injecting reset packets. We also observed specialized behavior of some devices in Russia that made them harder to detect.”

Network Responses to Russia’s Invasion of Ukraine in 2022: A Cautionary Tale for Internet Freedom

Global Online Censorship

Censorship and enhanced surveillance are used by the same authoritarian regimes and bodies, and they generally serve the same purposes. If a government is engaging in one, there is no reason to assume they are not engaging in the other.

Clive Robinson March 30, 2023 2:33 AM

@ Winter,

Re : Laws of Nature -v- Man again?

“then be must receive the text/speech/picture in a legible form. Period.”

Any judge decreeing that would quite rightly get treated with contempt and derision and rightly so.

Have a little think on it as you would be trying to “square the circle” yet again.

But it’s a more subtle problem than just a hand wave response.

To see why, an easy little test for you,

Q: If you increment by one 1,999 what is the result?

We all know how to add one so, you should be able to come up with thr correct answer in just a couple of seconds, Yes?

ResearcherZero March 30, 2023 2:35 AM


Security properties of MLS include message confidentiality, message integrity and authentication, membership authentication, asynchronicity, forward secrecy, post-compromise security, and scalability.

Messaging Layer Security: Towards a New Era of Secure Group Messaging

Asynchronous Ratcheting Tree

“Politicians can whine all they want, but they can’t change standards as easily.” <- but they can change laws to insert backdoors.


Clive Robinson March 30, 2023 3:25 AM

@ Renee W,

Re : Lost in translation.

“I find the use of the word “should” a bigger problem. Laws are generally written as “shall” and “shall not”, not “should” (which almost contradicts the idea of a “rule”).”

I very rarely “go to thr source” with EU proposed legislation and dirrctives.

Because the process has a problem that I once saw very nearly go wrong, and could have had life endangering consequences as a result.

Put simply the process is,

1, The draft is done in Language A.
2, The draft in Language A is approved.
3, Member nations are given a fixed time period to implement the legislation / directive in languagr A into their national statutes.

Sounds easy but it’s not.

Because most nations do not have their law written in Language A but some other language, say B.

This gives rise to all sorts of translation issues, especially with words like “secure” that have multiple meanings in both languages A and B so you have an “imperfect many to many translation” issue at best. But what do you do when language A has a legal meaning / definition / use that is not in language B?

We’ve seen enough legal nonsence over the “Oxford Comma”[1], trust me when I say there is worse just waiting…

As an overview to the trouble with “meanings” there are the troubles in the US with people in Government agencies redefining or assigning new meanings to words, so they can lie, cheat, and steal. We’ve seen it with the NSA redefining words so they can do what others would rightly consider things they had been clearly prohibited from doing, and a lot worse (which I won’t mention due to moderation issues).

[1] The “Oxford” or “serial” even sometimes “hanging” comma appears in a list after the penultimate item in a list of three or more items and preceeds the logical AND or OR indicating the list type.

It causes ambiguity as a legal case in Maine highlighted,

Unfortunately the article only goes to cover the issue partially. With the form,

“My parents, Alice and Bob”

The argument they are effectively making is that the lack of the Oxford comma makes Alice and Bob your parents. Well that is one interpretation of the Oxford Comma issue… but you can see a second raise when you say,

“My parents, Alice and Bob Smith”

That is are Alice and Bob Smith being treated as two list items “alice” and “bob smith” or as one list item “alice and bob smith”. Usually it does not have ambiguity as

“Use the washer, nut and bolt”

Does not… But,

“Use the bolt, nut and washer”

Can with there now being the availability of “nuts” with attached “washers” as single items.

Lists are never supposed to be treated in this way, as they in effect start becoming trees, but humans are lazy and the English language positively revels in lazy usage… And just one of many reasons “language warps the way you think”.

Clive Robinson March 30, 2023 4:13 AM

@ lurker, iAPX, SpaceLifeForm, Winter,

Re : It’s Three party not two.

“The trick is whether the judge can get both A and B to stand up in court and say, yes they fully understood the capability of each other’s phone.”

That is not what the legislation is about… The legislation cares not a jot about the end users A and B or their equipment compatability.

The legislation forces a “gatekeeper” in between the two of them and makes it the legal responsability of the “gatekeeper” not the “Users” not just to know the capabilities of the users equipment and software but also be able to “transcode” the data from one format to the other under all circumstances even when it is not possible[1].

Now consider just how much information each user would have to hand over to the “gatekeeper” about their devices, software, revisions, dates and times of updates etc. More than sufficient to “uniquely fingerprint” thus identify a device and so the user.

And that’s before also having to hand over all encryption keys etc to get the message content in a format that can be transcoded… Which currently means that the plaintext will be revealed.

So in effect this legislation is forcing on users a system for monitoring and censorship, that is actually worse than the “on device” system Apple tried to implement on the pretence it was only to catch CSAM, which we all know was “An abusable nonsense” as in reality it was “A wide opening unlocked back door”.

Remember under US and other jurisdictions legislation authorities obtaining access to all of this as it’s “third party business records” requires no warrent and is not subject to any oversight legal or political.

It does not matter how “shallow” you make the information on file formats etc, each piece of information is a piece of your “Privacy Leaked” with each piece striping you more and more naked infront of malevolent eyes you can not see…

Thus this legislation is worse than alowing anyone to do “up skirt video recording” and then make as much profit or other benifit as they can from it.

[1] There are known ambiguities that can not be resolved with something as simple as “colour”. That is RGBi does not map to CYMK either uniquely or in some cases at all… Which is made worse by applying certain statistics flattrning tricks to acomplish a form of “data compression” much like is done with telephones and aLaw and ulaw encoding that gives a crude aproximation to logrithmic compression. Then there are “internationalisation issues” as an example with dates,

Q: What is 10122022?

The 10th of December or the 12th of October last year, or could it be a Julian style date as a count from an unspecified epoch using an unspecified count step size? All of those and more are valid in CSV format files…

Winter March 30, 2023 4:48 AM


But what do you do when language A has a legal meaning / definition / use that is not in language B?

The EU and predecessors have now existed for ~70 years and have drafted more laws than anyone would care to count. They employ an army of translated especially for legal translations.

They do know how to handle a simple requirement to interoperate in all the EUs languages.

Peter A. March 30, 2023 4:53 AM

@SpaceLifeForm: You can not send an SMS to a POTS line.

Sometimes you can.

I still keep a POTS line (mostly for a better reliability in case of a power outage – however I can’t by sure these days). Quite some time (years?) ago, while sending an SMS to a family member, I have selected a wrong entry in the phonebook, which contained our land line number, then put my phone down. A couple of seconds later the landline phone started ringing. “Why the person is calling me back on the landline?” – was my first thought. I picked up and had my SMS read back to me… Later, I’ve spotted an extra item on my mobile phone bill 🙂 Not a significant sum, of course, but it stood out as a paid SMS, while normally all my SMSses were not billed, as there was a pool of N free SMSes per month in my plan. Apparently, it was a special text-to-speech service by my mobile provider. I am not sure if it is offered still.

I can’t wait till I can send an MMS to the landline and have some AI paraphrase the picture or video… (just kidding)

Winter March 30, 2023 5:01 AM


I could not wait to see that in action, with the receiver using a dumb phone and thus limited to SMS…

This does not sound like a genuine objection. Courts are very experienced in handling obstinate parties. If a platform accepts a certain type of messages, it should accept them from everyone. If it doesn’t accept a certain type of messages from anyone, it won’t be forced to do so.

The same type of objections were fielded against “source code” as used in the GNU GPL. They don’t fly there either.

As for E2E encryption, that is at the risk of the sender. If a platform warns about confidentiality crossing applications, the sender should make a decision. Not much different from messaging to SMS as is already done in Apple message (which Apple seems to make as painful as possible for the receiver).

But these regulations will apply to big platforms, not something you conjured up for your model train LUG. As for different modalities, every big platform supports UTF and ASCII/Latin in some form, they all support jpeg, gif, png, wav, mp4, and mp4 (all international standards). If they don’t, there is already something fishy.

In short, every objection I have seen is about obstructing interoperability, not impossibility of interoperating.

Winter March 30, 2023 5:15 AM


Any judge decreeing that would quite rightly get treated with contempt and derision and rightly so.

I would like to remind you how the EU handled interoperability in cell phones (cf, USA), and power plugs. There were a lot of objections there too that did not make much hay. Interoperability has been at the heart of EU policies from the start as every country was trying to game the system.

Q: If you increment by one 1,999 what is the result?

Depends, it can be 2,000.000 or 2,999.

That already affects users of the same platform. I have to deal with this in spreadsheets all the time. There are good international standards in how to solve this. As platforms already deal with this for their own customers, there should be no legal valid reason not to deal with it for users of other platforms.

The really easy part for judges is that platforms should not treat messages from other platforms differently from those on their own. And if platforms refuse to use international standards outright for no valid reason, then, maybe, they should be forced to do anyway?

lurker March 30, 2023 2:27 PM

@Clive Robinson

Of course its a three party problem, but if A and B agree, then the judge can flick the problem straight onto the gatekeeper, which is what this thread is about.

Clive Robinson March 30, 2023 8:00 PM

@ SpaceLifeForm, modem phonemes, ALL,

Re: railway gauges

“IIRC, courses for horses.”

Actually “Roman courses” to stop chariots and wagons getting stuck. Julius Ceaser passed the 4 ft 8 & 1⁄2 in track width into law.

It’s actually a “usefull trade off” on the graph curve between turning circle and stability, at what ever speed you can reach.

As a very rough rule of thumb the width of the track is about half that of the pulling shaft end and the wheel hub. As speed increases so does the length of the shafts thus the size of the turning circle. Which is why horse drawn coaches in Europe were almost never above “two pair” except for “ceremonial and heavy load drafts, where the shafts were often segmented.

But the wider the width of the track the faster you can safely go, so…

Brunel for his Great West route used a very wide track giving not just speed but comfort. He could only do that as the run to Bristol was nearly flat and straight all the way.

When you have mountains with twisty paths and ledges to run on or holes in the ground with coal or rock being extracted speed and comfort are not criteria that are important thus you had 15inch “narrow gauge” as opposed to Brunel’s 7ft “broad gauge” or one of the many “standard gauges” based close to Gerorge “Stephenson gauge” at 4 ft 8 & 1⁄2 in, which was actually Julius Cesar’s legal guage (It’s said Stephenson just measured the ruts in the Roman Road flag stones, though it’s more likely it was an “artisanal norm” for coach builders of the time that he just followed for convenience and lower cost).

Some “wide guages” were “as big as a house” at nearly 30ft wide, but they were not usually for trains, you can still see them on some older docksides where they were used by the very large steam and later electric cranes used for loading and unloading ships prior to “container vessels” becoming a norm.

ResearcherZero March 30, 2023 10:27 PM

No one thinks about the profit model of the poor old commercial spyware and surveillance industry. Instead they only worry about themselves.

“…most spyware vendors offer SS7 spying, which takes advantage of vulnerabilities in the mobile network.”

Clive Robinson March 31, 2023 12:31 AM

@ ResearcherZero, SpaceLifeForm, ALL,

Re : Profit and loss privacy.

I know this is ‘tongue in cheek’,

“No one thinks about the profit model of the poor old commercial spyware and surveillance industry.”

But three points to note,

1, Some here do care how the profit is made.
2, We know the business models are technically illegal.
3, We know the companies are protected by nation states.

Oh and as the money comes from the “tax payers pocket” these less than lawfuly behaved companies are in no way “poor”.

Think of the companies and especially their seniors sucking on the teats of billions of dollars of state handouts/subsadies… With we assume as is normally the case some kind of “kick-back” to the political and legaslitive representatives as a mininum… with we can also safely assume “nest feathering” of those who have, or still do, receive salary direct from the public purse (civil servants, guard labour, etc).

But there are three asspects that have to be considered,

1, For a market to exist there has to be customers for it’s services.
2, To be able to provide these services systems have to be exploited.
3, For the services to be exploited they have to be vulnerable in some way.

Kick away any one of those three legs and either the market will topple or be at best dangerously unstable.

As an engineer I know the best leg to kick away to ensure the market topples compleatly is the third one.

That is if the services are not vulnerable, then they can not be exploited.

The problem with this is that the entire ICT industry is set up to encorage vulnerabilities to be permanently embedded at the lowest levels. This is not helped by those behind Elected Governments deliberatly trying to make ICT and associated systems as insecure as possible “for their own benifit”. A look at the history of the US FBI should make that abundently clear, even though so many still want to stick their heads in the sand, thus leaving themselves in an ass-up vulnerable position open to a sense of intrusion few would want to suffer, but one that the likes of the FBI happily take advantage of over and over.

One of the reasons “the technology is broken” is due to history. I and several other readers here were alive and had an interest in what we now call electronics or communications before semiconductors had got as far as “Medium Scale Integration”(MSI) chips[1].

The problem was the resources were increadibly expensive and an almost infitesimal fraction of the cost/capability you can get today (you can get a 20cent chip that can act just like a Micro-Vax CPU and Memory systems).

Thus “bang had to happen for the buck” so for the same reason we had Y2K we have no real security. Worse unlike Y2K that had to be fixed, nobody realy cares about fixing security. So we are running highly insecure systems like SS7 that started their life over half a century ago and were never designed to be secure in any way. And nobody is going to make them secure because they dare not, as even looking to hard at the standards would break them. And with that the worlds largest machine of the telecoms network would break with them probably unfixably… The only way to fix the security is,

“To start again”

They tried this with IPv6 and IPsec in the 1990’s and I think you can see how far that has come near a third of a century later (more correctly ‘has NOT come’).

Most is not all the low level protocols based around IP networking are not just “insecure” but actually “broken” thus known to be vulnerable in some way… Have a look at the software that manages switches and routers every so often another “bug that’s been there for more than 20years” pops up, and it’s a certain bet there are not just more to be found, but some are actively being used in exploits as “zero days” for APT and similar.

So if we can not fix the technology, we need to fix the law, and make the activities of these companies actually a crime, with hard jail sentances for top level executives and those that reward them (Venture Capitalism is currently the biggest security threat enabler as they see it as a more profitable place to play than rigging the finance markets).

But realistically nobody with the ability to change the legislation will do so, because there is way to much “Dark benifits” incentivising the opposite behaviour.

As for killing the market by killing off customers, any legislation that might act as such an enabler will be hobbled in some way. Probably to make legitimate security research that outs Zero Days and similar vulnarabilities illegal in some way.

So untill sufficient people pull their head out of the sand and put legislators in fear of their political lives that any incentives this nefarious industry can offer will be insufficient, it won’t happen…

I hate to say it but people need to look at how the anti-abortion cultists currently work in the US, and repurpose their techniques to get legislative change, that will have the same effect as Dec 1999 did for Y2K. Then maybe we will have a chance of getting Privacy secured so that society as we want it can survive.

[1] That is before calculator chips and the later first 16bit bitslice ALU chips that became the core of computers and eventually CPU chips in the 1970’s. In my case I was a licenced amateur/ham in the 1970’s before the boom in 8bit and later 16bit desktop computers of the 80’s. My interest in the early 70’s had made me a keen “satellite tracker”, in part having started “doing Pirate Radio” all whilst still at school. Then studied electronics and communications professionaly having started being a design engineer in time to ride the leading edge of the computer boom. I’d even written my first non trivial computer program before the mid 70’s and had written for that time proffessional grade satellite tracking software just after the mid 70’s that also produced a world map with an orbital overlay on high end Tektronix graphics terminals and chart plotters, that gave not just the “Subsatellite Path” ground track but the “Aquisition Of Signal”(AOS) tracks and time/inclination “web” lines. A later version output data to drive a “servo system” to control an antenna array (it ended up being used for a while at a University that had it’s own “ground station”).

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