Perhaps it relies on using obscure information that the messenger already knows, but not telling the messenger which random fact will be the significant one.
For example, you could authenticate my brother by asking him to complete this song title: "Fleshy _______". Yet without knowing what question he was to answer, he could never retrieve the password.
I suppose it's not exactly true that he couldn't remember it-- it's in his memory, but he doesn't know where to look. Actually, the idea is basically asking someone to dereference a pointer to their childhood. Most people will segfault.
So essentially we're relying on a one-way hash function, which is what I am thinking too. (In Quantum Information Theory, the question whether or not there exists true one-way hash functions is still unanswered, but for the time being, current cryptographic functions are obviously working well enough).
I feel like this wouldn't work with humans though. For instance, if I was torturing you and knew that your brother was the other agent, I might think to ask you for any inside jokes between you and your brother. There's a chance you wouldn't think of the right one (i.e. segfault analogy), but also a chance that you might, so you haven't really "forgotten" the answer.
On top of that, I feel like something straight out of Harry Potter probably isn't the answer :)
I like the idea (in the comments on OP's blog) of using a very unique smell. You can explain what's happening in a picture or hum a melody, but maybe a smell is more difficult to describe.
I was thinking something similar, maybe it was a common sequence like Supercalifragi___icexpialidocious or the alphabet (with a letter missing) where when asked, the user could fill in the part of the sequence, but would later forget the exact offset for.
Someone posted on the original article that "You cannot recall smells..." That is one possibility. Pandarus could give Manelaus a bottle of a very specific perfume that Pandarus was familiar with. If Pandarus smelled the perfume in the future, he would know it was Manelaus. But if captured, he would not be able to remember the perfume's smell -- at least not in a specific enough way to reproduce it.
I agree. Actually, the secret needs to be something that can be remembered well but not described well. Smell and maybe taste are very well suited for this.
Anecdotal evidence: I recently learned how a dead mouse smells but cannot think of any way to describe this smell. However, I could definitely identify this smell again.
I have a question - what does 'give an identity check' actually mean? Does it mean that Pandarus has to give Menaleus a means of verifying that Pandarus really is Pandarus in the future, or does it mean that Pandarus has to verify Menaleus' identity?
Ya, I'm wondering that myself. Or it could mean that Pandarus gave Menaleus a way for Menaleus to identify himself (Menaleus) to others. If so, then it could be something unique to Menaleus such as his finger print. Menaleus could use his finger print as an identity check and Pandarus would have no way to remember Menaleus' finger print.
The picture thing got me thinking. Perhaps PANDARUS had an eidetic memory. He had studied a picture that MANELAUS had access to. MANELAUS could simply ask a question about some minor detail in the picture. The picture would be selected such that there are too many such details to communicate a substantial fraction of them.
If asked the question "what is your identity" and you were told to reply "I am unable to remember it" under all circumstances, or a variation on that - would that work?
Not really, because while you are being tortured you would explain in detail "I am supposed to repeat the exact following phrase 'I am unable to remember it'". It's not like torture just makes you answer only technically correct but able to withhold actually giving them what they want.
What you are describing would probably work in a sitcom, but it makes no sense in real life.
I think the photograph idea gives a hint (though is unlikely to be unique), say there was a picture of the Queen/President in some recognisable location in their office. They could be asked, "where is the xxx standing in the portrait in your office". This may be what the linked article says, don't know, haven't read that (yet).
EDIT on thinking about it, a password is an answer to a question (what is the shared secret?), it's not the password they don't know, it's the question.
It seems to me that if I were doing something like this, I'd have some way of indoctrinating people without them knowing it. Some information or phrases that seem very commonplace and non-important, but will trigger certain responses when they're seen or heard again.
We've already got quite a few that are easily spotted by an enemy. When the national anthem plays, what do you do? It's pretty easy to spot people who don't know.
In fact, we already use this to spot enemy agents. They will react in odd ways to things that we think of as commonplace... Words and phrases that mean something in the culture, but on their own are meaningless... Or just have changed usage.
The only thing that makes me think the above is NOT what they used is that they said they would have to find a way to vary it. It takes time to make the above happen, but varying it isn't a problem other than that.
This has happened to British Agents before in WWII. I remember seeing a documentary about training British agents to infiltrate France. While in France one agent got caught out by asking for a black coffee. This was the default coffee at the time in France, people would just ask for a coffee and expect a black coffee. This made him stand out.
There are similar stories like this in movies, such as the Great Escape, when one of the escaping prisoners is dressed as a civilian and is boarding a bus in town. A German Officer says in English "Good luck", the prisoner replies in English "thank you" and is caught.
> In fact, we already use this to spot enemy agents. They will react in odd ways to things that we think of as commonplace...
This is used in Inglorious Basterds, where an American agent is found out because he counts to three with his three middle fingers instead of his three first fingers (including the thumb).
Asimov, I think it was, wrote a short story where the German spy during WWII was identified "or the gloom of the grave" as the words following "From the terror of flight." Those being from the third verse of the US National Anthem.
Of course, few Americans know anything other than the first verse, but the over-prepared German didn't know that.
What if the messenger was Anosmic, and the person verifying his identity had a very strong odor. He would never be able to identify the other person by that trait.
Basically, the second person had to have some sort of trait that was easy for other people to see, but not for the messenger. Perhaps colorblindness could have been a factor.
Interesting. I've read a few stories about spies being discovered due to their habits, so this is somewhat related. For example, table manners are different in Europe and the US (the way you hold and use a knife and fork especially). Also, since people in the uk drive on the left the way they look for cars before crossing a road is opposite the norm in countries where they drive on the right. Apparently Americans will rotate a piece of pie or cake so the point faces them before eating it.
It should be possible to specifically train some habit or combination of habits that is within the norm but notable enough to use as an identifier if known (much like baseball signals).
You might be interested in this interview which came out just yesterday [1] about techniques for detecting people by the way they walk (apparently, throughpressure point patterns in a digital footprint) with (IIRC) 99.6% precision.
Regional identification through manners and/or phonology goes back to the concept of a shibboleth [2]. This is used rather wonderfully as a turning point in many stories (without spoiling too much, I should mention that Tarantino pulled this off nicely in one of his films).
Maybe he has a scar on his face and the password is "how did you get that scar?". Has the text says, the scheme cannot be used with other people so it's probably something specific with the agent.
The text says unless they can think of a way to vary the scheme, it can't be re-used, presumably because it's not useful as an identity check if it cannot uniquely identify a single person.
[+] [-] pingswept|14 years ago|reply
For example, you could authenticate my brother by asking him to complete this song title: "Fleshy _______". Yet without knowing what question he was to answer, he could never retrieve the password.
I suppose it's not exactly true that he couldn't remember it-- it's in his memory, but he doesn't know where to look. Actually, the idea is basically asking someone to dereference a pointer to their childhood. Most people will segfault.
[+] [-] dcosson|14 years ago|reply
I feel like this wouldn't work with humans though. For instance, if I was torturing you and knew that your brother was the other agent, I might think to ask you for any inside jokes between you and your brother. There's a chance you wouldn't think of the right one (i.e. segfault analogy), but also a chance that you might, so you haven't really "forgotten" the answer.
On top of that, I feel like something straight out of Harry Potter probably isn't the answer :)
I like the idea (in the comments on OP's blog) of using a very unique smell. You can explain what's happening in a picture or hum a melody, but maybe a smell is more difficult to describe.
[+] [-] kgen|14 years ago|reply
[+] [-] unknown|14 years ago|reply
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[+] [-] rottendoubt|14 years ago|reply
[+] [-] raphman|14 years ago|reply
[+] [-] demallien|14 years ago|reply
[+] [-] rottendoubt|14 years ago|reply
[+] [-] amalcon|14 years ago|reply
[+] [-] chris_dcosta|14 years ago|reply
[+] [-] esrauch|14 years ago|reply
What you are describing would probably work in a sitcom, but it makes no sense in real life.
[+] [-] highjeep|14 years ago|reply
(...Pandarus who'd blasphemed so frequently...)
Clever but weak, there is plenty of blasphemers in the world.
[+] [-] epo|14 years ago|reply
EDIT on thinking about it, a password is an answer to a question (what is the shared secret?), it's not the password they don't know, it's the question.
[+] [-] wccrawford|14 years ago|reply
We've already got quite a few that are easily spotted by an enemy. When the national anthem plays, what do you do? It's pretty easy to spot people who don't know.
In fact, we already use this to spot enemy agents. They will react in odd ways to things that we think of as commonplace... Words and phrases that mean something in the culture, but on their own are meaningless... Or just have changed usage.
The only thing that makes me think the above is NOT what they used is that they said they would have to find a way to vary it. It takes time to make the above happen, but varying it isn't a problem other than that.
[+] [-] hasslblad|14 years ago|reply
There are similar stories like this in movies, such as the Great Escape, when one of the escaping prisoners is dressed as a civilian and is boarding a bus in town. A German Officer says in English "Good luck", the prisoner replies in English "thank you" and is caught.
[+] [-] bambax|14 years ago|reply
This is used in Inglorious Basterds, where an American agent is found out because he counts to three with his three middle fingers instead of his three first fingers (including the thumb).
[+] [-] dalke|14 years ago|reply
Of course, few Americans know anything other than the first verse, but the over-prepared German didn't know that.
[+] [-] pepsi|14 years ago|reply
Basically, the second person had to have some sort of trait that was easy for other people to see, but not for the messenger. Perhaps colorblindness could have been a factor.
[+] [-] keenerd|14 years ago|reply
[+] [-] InclinedPlane|14 years ago|reply
It should be possible to specifically train some habit or combination of habits that is within the norm but notable enough to use as an identifier if known (much like baseball signals).
In short: behavioral steganography.
[+] [-] michaelbuckbee|14 years ago|reply
Finger Counting: http://en.wikipedia.org/wiki/Finger_counting - this is what caught up Tarantino's Inglorious Basterds.
Cash Counting: http://www.youtube.com/watch?v=g87HVlu55mQ
[+] [-] rufibarbatus|14 years ago|reply
Regional identification through manners and/or phonology goes back to the concept of a shibboleth [2]. This is used rather wonderfully as a turning point in many stories (without spoiling too much, I should mention that Tarantino pulled this off nicely in one of his films).
[1] http://www.cbc.ca/spark/2011/10/todd-pataky/
[2] http://duckduckgo.com/shibboleth
[+] [-] mhb|14 years ago|reply
[+] [-] unknown|14 years ago|reply
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[+] [-] shin_lao|14 years ago|reply
Maybe he has a scar on his face and the password is "how did you get that scar?". Has the text says, the scheme cannot be used with other people so it's probably something specific with the agent.
[+] [-] eridius|14 years ago|reply
[+] [-] palish|14 years ago|reply
[+] [-] unknown|14 years ago|reply
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[+] [-] unknown|14 years ago|reply
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[+] [-] gcb|14 years ago|reply
Make a clown delivers the mission, and not mention any identity check procedure.
If caught, he will not even know about id check to give out.
If reach destination, he may be asked something about the clown costume. Which he would never forget because of the out of placeness of the thing.