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2

I'm not fully sure if this paper about time-lock encryption has been inspired by this discussion but it would be the most formal solution to the question "How to build time-lock encryption?", which is a reformulation of "How to protect data so that it can only be decrypted after a specific date?" But now let's get into the details on how this works. One ...


0

It could be possible to build a blockchain based system that gives every block in the future additional payload that the miner of that block has to solve. Every block could create a private key for a public key that's known in advance. You encrypt your message with a symmetric key and then encrypt that key with the known public keys of the next 10000 ...


0

Encrypt with a one-time XOR pad and have some kind of automation to send the cipher stream at the appointed hour. One time XOR pads are completely resistant to pattern attacks because there's no pattern. For this to succeed you must produce the key yourself and not share it with anyone build tamper-proof timed delivery automation conceal the true ...


0

Ultimately, the second law of thermodynamics gets in your way. Look at your plaintext as a closed system; it can only ever increase in entropy. Encrypting information increases its entropy, but having the key compensates for it. The total entropy of key+ciphertext is the same as the entropy of the plain text. When you destroy the key, the overall entropy ...


4

If the only trusted party is yourself, and you can't guarantee being available when the message contents are to be made public, then what you can do instead is to build a device (physical or virtual) that will automatically make the key public at the required time, and then hide the device. An easy way would be to buy a virtual server from Amazon or any of ...


0

Like others said, one cannot provide decryption by a specific date, but by a specific effort. As for a single purpose algorithm the effort is strongly related to the interest of the partys trying to unlock it earlier and thus quite unknown. So the best solution may involve linking the puzzle to a much larger and inert interest. The most feasable that came ...


16

Use secret sharing to split a private encryption key into N parts, parameterized to allow reconstruction of the key with K or more parts, where K <= N. Best done using CRM, as described on the following page: http://en.wikipedia.org/wiki/Secret_sharing Then send each part to independent services that agree to publish at a given date in the future. Up ...


43

Carefully place a spaceship broadcasting the decryption key in orbit around a black hole. The pull of gravity will delay the message until the appropriate time. Or you could just do like normal people and place the key broadcasting spaceship an appropriate number of light years away from the intended audience.


-1

The only way you can do this is to ensure that a) you control the code that performs the decryption, and b) that you are getting the date from an immutable source. For example, if you include as part of your decryption a call to an atomic clock web service (ideally a secure one that couldn't be spoofed). At that point, you just check the date and if it's ...


1

A hypothetical approach is given in the paper cited in the question (which is very interesting BTW, despite the occasional clumsy grammar) which is to use a software containing an encrypted payload, triggering off of some outside value like a news story, and have people around the world run it until such time as the payload is executed. This fails to meet ...


1

Encrypt the file with a very long key, split it up into parts, and give each part to a trusted person along with instructions not to surrender said part until the given date. You may add some redundancy by giving each part out to more people, in case one of them were to be hit by a bus. Of course, a network of computers could do this just as humans can. In ...


7

I believe that in order to properly design your system, you need to define what "time" means in your context, and why you chose a specific time. Assuming that your message is to be decrypted on the 29th of August 1997 at 02:14 AM, what is difference between the moment before and the moment after the deadline? Why specifically this date? You may be able to ...


66

Time is relative. Cryptography lives in the ethereal world of abstract computing machines: there are machines that can do operations. Bigger machines can do operations faster. There is no clock that you can enforce; physical time has no meaning. In other words, if an attacker wants to get your file earlier, he just has to buy a faster computer. Now one can ...


55

If you do not want to involve a third party, you (the party encrypting the file) could simply release the key to decrypt the file on the target date. I have seen this done for video game releases. Customers are allowed to download an encrypted copy of the game in advance. Then, when the release time comes, the game company simply releases the key. That way, ...


2

Your protocol is not safe by any means! Example for MitM: A sends random nonce G1 to B C intercepts and sends nonce G1c to B B sends back hash_k(G1c) and random nonce G2 C intercepts and sends hash_k(G1) and nonce G2c to A A verifies hash_k(G1) (is OK), then sends back hash_k(G1 | G2c) C intercepts and sends back hash_k(G1c | G2) B verifies and a ...


1

No. Stick to known protocols such as TLS, Kerberos, SSH & IPSec for key exchanges. Try researching Diffie-Hellman key exchanges and ECDH (Elliptical Curve Diffie-Hellman, the new method of key exchanges like your example).


1

CAN is designed to be relatively simple and is often implemented between microcontrollers with very little processing power (that are busy doing stuff where timings are important), and is used to relay messages in real time. Adding some encryption and DoS protection would introduce too much complexity and given that it's just two wires shared by all ...



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