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  • 8 votes cast
Mar
21
comment Which algorithm can be performed by humans?
I dont think its mono-alphabetic, because with my brother I would take the key on the left. And with my mother the upper key. Or would it still be mono-alphabetic in this case?
Mar
20
comment Are factorization algorithms parallelizable?
Im asking if the process of factoring an integer can be done in parallel? For example, in audio or video decoding its very easy to split the job across threads/processes or even machines. Bruteforcing a hash can also be split across multiple machines. But some tasks are hard to split the work, and I want to know which category this falls in.
Mar
19
comment What happens when a RC4 stream gets corrupted?
I just consider it, I dont have to do nothing
Mar
19
comment What happens when a RC4 stream gets corrupted?
The problem is that the secret is easily predictable (you add known bytes to the key). And the reset is kind of expensive, i wish I could keep the state and still be able to do random reads
Mar
19
comment What happens when a RC4 stream gets corrupted?
I write the 200 MB file in 2 KB blocks. Does it make sense to reset the keystate for every block? Or is it better to initialize it only once for the whole file?
Mar
19
comment What is the most light-weight symmetric cipher thats still usefull?
@cpast I mean power+memory requirements. Decryption can be very slow, but encryption (which is done on the device) must almost be costless like Virgene cipher.
Mar
19
comment What is the most light-weight symmetric cipher thats still usefull?
@LightBit Yes, but I underclocked to 12 Mhz instead of 48, and Im not running from RAM but from FLASH, so I will never reach those numbers.
Mar
18
comment Reusing a one-time pad?
@MaartenBodewes The max clock for a Cortex M0 is 48Mhz, and I underclocked 4 times. The device is a batterypowered sleeprecorder so it doesnt need to be fast as long as it can do its job.
Mar
17
comment Reusing a one-time pad?
@CodesInChaos I picked RC4 because it looks so simple. So can you add your comment as an answer so I can accept it.
Mar
17
comment Reusing a one-time pad?
Is TripleDES faster or slower than RC4?, because I picked RC4 now.
Mar
17
comment Reusing a one-time pad?
@MaartenBodewes Its an Cortex M0 running at 12Mhz, so its not so fast. And I need to save battery. I was in doubt between RC4 and XXTEA and I picked RC4 now. It seems good enough.
Mar
16
comment Reusing a one-time pad?
@CodesInChaos If RC4 is more light-weight than AES, I will accept your answer. I also find some other algorithms (LED, PRESENT, Piccolo) but I dont know how they compare to RC4, and I dont want to do a whole comperative study.
Mar
16
comment Reusing a one-time pad?
It's an ARM Cortex M0, so I may be able to find a AES implemenatation, but I want to save battery on the device as much as possible and security is not so important.
Mar
16
comment Reusing a one-time pad?
@Thomas The data are brainwave signals, so they are pretty random, And I know its not fool proof, but it must be the best it can be given the restrictions. Can I not shift the XOR array one position to the right after each XOR for example? That would be a simple improvement
May
14
comment Is there a way to do fair exchange between two parties who don't trust each other?
@HenrickHellström The exchanged message would be a private key of cryptocurrency, so both parties are actually exchanging something of value, and aborting would be too late. Ill guess its just not possible without trusted mediator.
May
14
comment Is there a way to do fair exchange between two parties who don't trust each other?
I've read the references you gave, but it seems there has been done very little research in this area. I cannot find any well-known protocol or implementation.
Jul
13
comment Signatures: RSA compared to ECDSA
@DavidSchwartz To verify the signature I need the full public key, how would this function with only a secure hash in the mail-headers?
Jul
12
comment Signatures: RSA compared to ECDSA
@poncho Unfortunately not, because it's a decentral system (like email), so having a central authority where users would need to sign up to have their identifiers mapped to keys, will undermine the whole concept.
Jul
12
comment Signatures: RSA compared to ECDSA
"Does that mean that the verifier uses that public key to verify the message?" It is used to identify the senders, so you can add them to a white-list. If someone else signs the same (or a new) message, you can see that it wasn't from the same person you whitelisted.
Jul
12
comment Signatures: RSA compared to ECDSA
It seems that ECC requires less space, but this paper (nicj.net/files/…) states "Thus, for applications requiring message verification more often than signature generation, RSA may be the better choice." And verification performance is critical in my case, so I will have to research how big the difference is.