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gem 'x25519' # raise if the gem x25519 is not installed
require 'x25519'
require 'net/ssh/transport/constants'
require 'net/ssh/transport/kex/abstract5656'
module Net
module SSH
module Transport
module Kex
# A key-exchange service implementing the "curve25519-sha256@libssh.org"
# key-exchange algorithm. (defined in https://tools.ietf.org/html/draft-ietf-curdle-ssh-curves-06)
class Curve25519Sha256 < Abstract5656
def digester
OpenSSL::Digest::SHA256
end
private
def generate_key #:nodoc:
::X25519::Scalar.generate
end
## string Q_C, client's ephemeral public key octet string
def ecdh_public_key_bytes
ecdh.public_key.to_bytes
end
# compute shared secret from server's public key and client's private key
def compute_shared_secret(server_ecdh_pubkey)
pk = ::X25519::MontgomeryU.new(server_ecdh_pubkey)
OpenSSL::BN.new(ecdh.diffie_hellman(pk).to_bytes, 2)
end
end
end
end
end
end
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