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seen Oct 24 at 14:30

Jul
2
awarded  Curious
Mar
19
comment How to verify a number encrypted with an unknown key
Do you have a source for the nth root ZKP?
Mar
18
revised How to verify a number encrypted with an unknown key
Added Link
Mar
18
answered How to verify a number encrypted with an unknown key
Mar
5
comment Zero-Knowledge Challenge-Responce Protocol
I'm sorry but I still don't get why you need this ZK protocol or what it exactly is supposed to do. If an authority signs the one-way-key the voter gets the signature as well as the certificate of the signing key for verification. The voter now sends the polling station his vote, his signed public one-way-key and the certificate. Based on a PKI the polling station is now able to verify the authority's signature. There is no need to contact the authority.
Mar
4
asked Security relevance of random factor in Paillier
Mar
4
comment Zero-Knowledge Challenge-Responce Protocol
I did not have a look at the paper you mentioned but in e-voting a voter usually gets something like an authentication token or a one-way signing key signed by an authority. For privacy reasons these signatures are often blinded.
Mar
4
awarded  Commentator
Mar
4
comment Questions about proof of correct encryption in the Paillier cryptosystem
Assuming "revealing r" would provide any information about the summands of a Paillier homomorphically added sum. Would it help to use primes as random factors for the encryption of the summands? I mean an attacker then would have to find an efficient way to factorize the resulting r.
Mar
4
comment Questions about proof of correct encryption in the Paillier cryptosystem
Now that you mention it I come to realize that the proof can be passed on without loss of authenticity. Its obvious but I did not think of it. As for me this is only partially a problem. Is there a way to turn "revealing r" into an interactive version involving a challenge? Would this solve the problem of transferable proof?
Mar
4
accepted Questions about proof of correct encryption in the Paillier cryptosystem
Feb
27
comment Questions about proof of correct encryption in the Paillier cryptosystem
I understand why revealing r is a correct proof of encryption. Also the ZKP presented in the linked paper seems to be no voodoo. What I don't get is why the authors of the said paper claim that revealing r also reveals useful information. I was afraid I missed anything and decided to ask here before asking the authors.
Feb
25
awarded  Editor
Feb
25
revised Questions about proof of correct encryption in the Paillier cryptosystem
Added probably closely related question
Feb
25
asked Questions about proof of correct encryption in the Paillier cryptosystem
Feb
6
awarded  Supporter
Feb
6
answered Zero-knowledge identification of the majority commitment
Jan
29
comment In the Paillier cryptosystem, is there a method to judge whether an encrypted number is less than 0 (without the private key)
As far as I can judge this ponchos counter-example makes different assumptions. In his case the blackbox is available to anyone and does not require the cooperation of any other party. So an attacker can query the box with any input he likes. However, in case of the Zero Knowledge Proof (ZKP) the proof stringently requires cooperation of the secret-holder. The basic idea of any ZKP is that a prover applying a ZKP can never reveal more to a verifier than what he has already stated.
Jan
27
awarded  Teacher
Jan
26
accepted Why is RSA usually limited to messages up to 1 block