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Quasars Used for Encryption
space_mongoose writes "According to this NewScientistTech story, intergalactic radio signals from quasars could emerge as an exotic but effective new tool for securing terrestrial communications against eavesdropping"
There doesn't seem to be anything special about a quasar here... essentially all they are saying is that large amounts of random data can be used for quick and easy one time pad encryption, which to my knowledge is unbreakable, although I am not particularly well versed in cryptography...
For those that don't know, the idea behind a one time pad is that your key is random, and the same size as the data being sent. For example, if binary data is sent, simple xor encryption can be used as follows
unencrypted data: 10110000
pad data : 10111001
xor the pad against the key and you get
encrypted data : 00001001
xor the same pad against the *encrypted* key again to get
original data : 10110001
tada
One time pads have two major problems
1. Both parties need the key.
2. The key is large, thus cumbersome to carry around and likely to be discovered.
Problem 2 can be solved, while losing some randomness, by using a popular book as the pad. Then you could just head down to the library and check out catcher in the rye, or whatever book you agreed upon beforehand, and begin decoding.
I suppose that this could be used in conjunction with public key cryptography, so that public key cryptography is used to encrypt the coordinates of the quasar you want to use... but I really don't see why you need the quasar at all. Also, aren't there only 12,000 of them visible? If this technology became widespread and quasars were persistently used as sources of random data... someone with enough resources could just monitor them all and decrypt any data transmitted by checking it against all the data received from pulsars at that time.
the length of the "one time pad" is large, but the number of them available? I mean the number of quasars that are good enough receivable to use for this purpose. I have no idea, but I doubt if its more than 2^32. In that case, brute force would be quite easy: just try each of the available quasar signals.:
Record the signal of each of them at time T, also record the encrypted message at time T, and try them all out in a fast computer. Then you'll know which one you need to use for the rest of the encypted source.
The number of real "one time pads" is much larger, given a decent random generator. But indeed their length is shorter, which is also good since using a one time pad for a very long time is not good if the one time pad somehow leaks.
...than using the noise from your soundcard disconnected mic?
It is just as random and does not require a radiotelescope the size of a small house...