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Feb
12
revised Safe and computationally efficient way to verify a curve25519 identity?
deleted 145 characters in body
Feb
12
comment Safe and computationally efficient way to verify a curve25519 identity?
@CodesInChaos, transmitted messages are encrypted and authenticated end to end using standard NaCl boxing. What the server does is relaying messages through the connection it thinks belongs to the destination of the message. An attacker could pretend to be someone else, and messages would be redirected to it, effectively preventing the actual destination to receive messages (DoS). If a man in the middle can effectively alter messages over the tcp connection, then all communications with the server should indeed be encrypted and authenticated as well.
Feb
12
comment Safe and computationally efficient way to verify a curve25519 identity?
@RickyDemer, It is used for end to end encryption, so ECDH shared keys should definitely not be shared. The other end is another client, not the server itself.
Feb
12
comment Safe and computationally efficient way to verify a curve25519 identity?
Also, I do not need encryption in this setting.
Feb
12
comment Safe and computationally efficient way to verify a curve25519 identity?
1) It is bound to a tcp connection. If arbitrary data is needed, the server can send a nonce. 2) how about a hash of the shared key ?
Feb
12
revised Safe and computationally efficient way to verify a curve25519 identity?
added 155 characters in body
Feb
12
asked Safe and computationally efficient way to verify a curve25519 identity?
Feb
2
awarded  Supporter
Jan
12
asked Is OCB with short MAC malleable?
Dec
26
awarded  Editor
Dec
26
revised Proof of shared secret through key derivation
added 164 characters in body
Dec
26
asked Proof of shared secret through key derivation
Dec
26
comment EC ElGamal versus static+ephemeral ECDH
What I referred to as static-ephemeral ECDH is effectively what is called ECIES. Thanks @DrLecter for clarifying. I still cannot find much benefit in using ElGamal for key sharing. I see mentions of homomorphism and malleability, which are of little use for this purpose.
Dec
26
awarded  Student
Dec
26
asked EC ElGamal versus static+ephemeral ECDH