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require 'net/ssh/transport/kex/abstract'
module Net
module SSH
module Transport
module Kex
# A key-exchange service implementing the "diffie-hellman-group1-sha1"
# key-exchange algorithm.
class DiffieHellmanGroup1SHA1 < Abstract
# The value of 'P', as a string, in hexadecimal
P_s = "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" +
"C4C6628B" "80DC1CD1" "29024E08" "8A67CC74" +
"020BBEA6" "3B139B22" "514A0879" "8E3404DD" +
"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" +
"4FE1356D" "6D51C245" "E485B576" "625E7EC6" +
"F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED" +
"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" +
"49286651" "ECE65381" "FFFFFFFF" "FFFFFFFF"
# The radix in which P_s represents the value of P
P_r = 16
# The group constant
G = 2
def digester
OpenSSL::Digest::SHA1
end
private
# Returns the DH key parameters for the current connection. [p, q]
def get_parameters
[
OpenSSL::BN.new(self.class::P_s, self.class::P_r),
self.class::G
]
end
# Returns the INIT/REPLY constants used by this algorithm.
def get_message_types
[KEXDH_INIT, KEXDH_REPLY]
end
# Build the signature buffer to use when verifying a signature from
# the server.
def build_signature_buffer(result)
response = Net::SSH::Buffer.new
response.write_string data[:client_version_string],
data[:server_version_string],
data[:client_algorithm_packet],
data[:server_algorithm_packet],
result[:key_blob]
response.write_bignum dh.pub_key,
result[:server_dh_pubkey],
result[:shared_secret]
response
end
# Generate a DH key with a private key consisting of the given
# number of bytes.
def generate_key # :nodoc:
dh = OpenSSL::PKey::DH.new
if dh.respond_to?(:set_pqg)
p, g = get_parameters
dh.set_pqg(p, nil, g)
else
dh.p, dh.g = get_parameters
end
dh.generate_key!
until dh.valid? && dh.priv_key.num_bytes == data[:need_bytes]
if dh.respond_to?(:set_key)
dh.set_key(nil, OpenSSL::BN.rand(data[:need_bytes] * 8))
else
dh.priv_key = OpenSSL::BN.rand(data[:need_bytes] * 8)
end
dh.generate_key!
end
dh
end
# Send the KEXDH_INIT message, and expect the KEXDH_REPLY. Return the
# resulting buffer.
#
# Parse the buffer from a KEXDH_REPLY message, returning a hash of
# the extracted values.
def send_kexinit # :nodoc:
init, reply = get_message_types
# send the KEXDH_INIT message
buffer = Net::SSH::Buffer.from(:byte, init, :bignum, dh.pub_key)
connection.send_message(buffer)
# expect the KEXDH_REPLY message
buffer = connection.next_message
raise Net::SSH::Exception, "expected REPLY" unless buffer.type == reply
result = Hash.new
result[:key_blob] = buffer.read_string
result[:server_key] = Net::SSH::Buffer.new(result[:key_blob]).read_key
result[:server_dh_pubkey] = buffer.read_bignum
result[:shared_secret] = OpenSSL::BN.new(dh.compute_key(result[:server_dh_pubkey]), 2)
sig_buffer = Net::SSH::Buffer.new(buffer.read_string)
sig_type = sig_buffer.read_string
if sig_type != algorithms.host_key_format
raise Net::SSH::Exception,
"host key algorithm mismatch for signature " +
"'#{sig_type}' != '#{algorithms.host_key_format}'"
end
result[:server_sig] = sig_buffer.read_string
return result
end
end
end
end
end
end
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