fix for hmac key deriving bug

2 files changed, 43 insertions, 7 deletions

diff --git a/lib/net/ssh/transport/algorithms.rb b/lib/net/ssh/transport/algorithms.rb
index 9c7f8d0..004a82b 100644
--- a/lib/net/ssh/transport/algorithms.rb
+++ b/lib/net/ssh/transport/algorithms.rb
@@ -28,7 +28,9 @@ module Net; module SSH; module Transport
       :encryption  => %w(aes128-cbc 3des-cbc blowfish-cbc cast128-cbc
                          aes192-cbc aes256-cbc rijndael-cbc@lysator.liu.se
                          idea-cbc none arcfour128 arcfour256),
-      :hmac        => %w(hmac-sha1 hmac-md5 hmac-sha1-96 hmac-md5-96 none),
+      :hmac        => %w(hmac-sha1 hmac-md5 hmac-sha1-96 hmac-md5-96
+                         hmac-sha2-256 hmac-sha2-512 hmac-sha2-256-96
+                         hmac-sha2-512-96 none),
       :compression => %w(none zlib@openssh.com zlib),
       :language    => %w() 
     }
@@ -351,8 +353,8 @@ module Net; module SSH; module Transport
         cipher_client = CipherFactory.get(encryption_client, parameters.merge(:encrypt => true))
         cipher_server = CipherFactory.get(encryption_server, parameters.merge(:iv => iv_server, :key => key_server, :decrypt => true))
 
-        mac_client = HMAC.get(hmac_client, mac_key_client)
-        mac_server = HMAC.get(hmac_server, mac_key_server)
+        mac_client = HMAC.get(hmac_client, mac_key_client, parameters)
+        mac_server = HMAC.get(hmac_server, mac_key_server, parameters)
 
         session.configure_client :cipher => cipher_client, :hmac => mac_client,
           :compression => normalize_compression_name(compression_client),
@@ -381,4 +383,4 @@ module Net; module SSH; module Transport
         end
       end
   end
-end; end; end
\ No newline at end of file
+end; end; end
diff --git a/lib/net/ssh/transport/hmac.rb b/lib/net/ssh/transport/hmac.rb
index 262db73..c2a79f4 100644
--- a/lib/net/ssh/transport/hmac.rb
+++ b/lib/net/ssh/transport/hmac.rb
@@ -2,6 +2,10 @@ require 'net/ssh/transport/hmac/md5'
 require 'net/ssh/transport/hmac/md5_96'
 require 'net/ssh/transport/hmac/sha1'
 require 'net/ssh/transport/hmac/sha1_96'
+require 'net/ssh/transport/hmac/sha2_256'
+require 'net/ssh/transport/hmac/sha2_256_96'
+require 'net/ssh/transport/hmac/sha2_512'
+require 'net/ssh/transport/hmac/sha2_512_96'
 require 'net/ssh/transport/hmac/none'
 
 # Implements a simple factory interface for fetching hmac implementations, or
@@ -16,11 +20,19 @@ module Net::SSH::Transport::HMAC
     'none'         => None
   }
 
+  # add mapping to sha2 hmac algorithms if they're available
+  MAP['hmac-sha2-256']    = SHA2_256    if defined?(::Net::SSH::Transport::HMAC::SHA2_256)
+  MAP['hmac-sha2-256-96'] = SHA2_256_96 if defined?(::Net::SSH::Transport::HMAC::SHA2_256_96)
+  MAP['hmac-sha2-512']    = SHA2_512    if defined?(::Net::SSH::Transport::HMAC::SHA2_512)
+  MAP['hmac-sha2-512-96'] = SHA2_512_96 if defined?(::Net::SSH::Transport::HMAC::SHA2_512_96)
+
   # Retrieves a new hmac instance of the given SSH type (+name+). If +key+ is
   # given, the new instance will be initialized with that key.
-  def self.get(name, key="")
+  def self.get(name, key="", parameters = {})
+    puts "digest key len: " + key.length.to_s
     impl = MAP[name] or raise ArgumentError, "hmac not found: #{name.inspect}"
-    impl.new(key)
+
+    impl.new(make_key(impl.key_length, key, parameters))
   end
 
   # Retrieves the key length for the hmac of the given SSH type (+name+).
@@ -28,4 +40,26 @@ module Net::SSH::Transport::HMAC
     impl = MAP[name] or raise ArgumentError, "hmac not found: #{name.inspect}"
     impl.key_length
   end
-end
\ No newline at end of file
+
+  # XXX copied
+  # Generate a key value in accordance with the SSH2 specification.
+  def self.make_key(bytes, start, options={})
+    if bytes == 0
+      return ""
+    end
+
+    k = start[0, bytes]
+
+    digester = options[:digester] or raise 'No digester supplied'
+    shared   = options[:shared] or raise 'No shared secret supplied'
+    hash     = options[:hash] or raise 'No hash supplied'
+
+    while k.length < bytes
+      step = digester.digest(shared + hash + k)
+      bytes_needed = bytes - k.length
+      k << step[0, bytes_needed]
+    end
+
+    return k
+  end
+end