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 Curious
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  • 47 votes cast
Oct
25
accepted Symmetric-like cyphers with several steps
Oct
23
comment Symmetric-like cyphers with several steps
I'm asking for a cypher with an algebraic property of the key material that allows the keys to be split into multiple parts to be used separately. There are several ways to do with with elliptic curves, but one needs something with symmetric-like speed and security, ideally including immunity to quantum computers.
Oct
23
comment Symmetric-like cyphers with several steps
Any cypher I know has the property that identical key material must be used both for encryption and decryption, meaning $k_i$ is a substring of $k_j$ for some $i \ne j$. At a consequence, any system using onion encryption has at most one "cut-out" node : en.wikipedia.org/wiki/Cut-out_%28espionage%29
Oct
23
asked Symmetric-like cyphers with several steps
Oct
13
comment Using a product of a series of curve25519 scalars as a private key
Alright, I suppose that answers everything then. In particular, one should not subtract curve25519 scalars because doing so would wipe out the most significant bit. And multiplication might get tricky too. Although one could protect against this by checking that the implementation does not fuck up and start with the most significant bit.
Oct
13
answered Are there any secure commutative ciphers?
Oct
13
awarded  Curious
Oct
12
revised Using a product of a series of curve25519 scalars as a private key
edited title
Oct
12
comment Why are the lower 3 bits of curve25519/ed25519 secret keys cleared during creation?
Ahh, thanks for the explanation. I just asked a slightly expanded version of this question here : crypto.stackexchange.com/questions/29791/…
Oct
12
revised Using a product of a series of curve25519 scalars as a private key
added 791 characters in body
Oct
12
asked Using a product of a series of curve25519 scalars as a private key
Jun
23
awarded  Caucus
Apr
8
awarded  Critic
Sep
12
awarded  Yearling
Jan
17
comment Information leakage from the ecryptfs filesystem
Is the only big difference between eCryptFS and EncFS that EncFS is userspace with all that entails, and requires users reserve another directory elsewhere for the encrypted files?
Dec
24
comment How does one design a traffic analysis resistant protocol?
Agreed, making the server useless was the whole point talking about "mailboxes". I think what I'd be most interested in is any rigorous analysis of what makes a server useless for traffic analysis while still making ordinary usage reasonable.
Dec
23
revised How does one design a traffic analysis resistant protocol?
added 173 characters in body
Dec
23
comment How does one design a traffic analysis resistant protocol?
I'd consider that "traffic analysis" refers to any attempt to discern the traffic pattern, but especially contacts/friends lists. I suppose one should view this on-server traffic analysis as a completely separate problem form internet traffic analysis.
Dec
23
awarded  Editor
Dec
23
revised How does one design a traffic analysis resistant protocol?
added 136 characters in body