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seen Dec 13 '13 at 9:15

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comment How much computing resource is required to brute-force RSA?
Thanks, but I'd really meant that once the factorisation you give has been discovered it can then be applied wherever the given product needs to be factorised. Over forty years with vast computing resources, many such factorisations could be discovered. I find @Maeher's answer more convincing in countering this argument, as it helps me to realise that the number of such factorisations required to be generated and stored even for 1024-bit RSA moduli is so vast that it is simply not reasonable even to hope for a collision with a known key.
Jun
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accepted How much computing resource is required to brute-force RSA?
Jun
25
comment How much computing resource is required to brute-force RSA?
Thank you for all of the additional links - lots of very useful reading! I suppose my perspective was whether due consideration had been given not only to the challenge of breaking RSA today from a zero-starting point, but had also factored in 40 years of effort?
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25
accepted Incorporating known ciphertext into new message
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25
accepted How can I encrypt + authenticate short strings into similar short ciphertexts?
Jun
25
asked How much computing resource is required to brute-force RSA?
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Jun
12
comment Incorporating known ciphertext into new message
@mikeazo: Trent will not know $p_1$, that's correct (it would otherwise be a trivial problem, I think?); however he will know (indeed, he will generate) $p_2$ as that would be the HTTP headers and/or other application-layer encapsulation of Alice's message. Alice and Bob do indeed have public/private key pairs.
Jun
12
comment Incorporating known ciphertext into new message
Okay, this was a dumb question as the actual session key negotiated between Trent and Bob won't be known by Alice in advance of that session. I presume therefore that there will need to be a higher encryption layer between Alice and Bob; it is simply not possible for Trent to store and forward HTTPS messages?
Jun
11
comment Incorporating known ciphertext into new message
What if the two messages are of different lengths? In my case, $p_2$ would be HTTP headers (generated by Trent) whilst $p_1$ is some arbitrary length message... Alice could inform Trent of its length if that wouldn't impair secrecy.
Jun
11
comment Incorporating known ciphertext into new message
@poncho: Duh, good point! Assume asymmetric cipher where only public key is known. I'm trying to devise means for Alice to store with Trent a message destined for Bob; Trent will later forward that message to Bob over pure HTTPS.
Jun
11
asked Incorporating known ciphertext into new message
Oct
18
comment How can I encrypt + authenticate short strings into similar short ciphertexts?
@PaĆ­loEbermann: Agreed. I have started a new question on SO seeking suggestions for excellent compression rates given the particular structure of domain names - see stackoverflow.com/questions/7801753/…