1 files changed, 12 insertions, 10 deletions
diff --git a/lib/srp/client.rb b/lib/srp/client.rb
index 22ed9f7..de17fb3 100644
--- a/lib/srp/client.rb
+++ b/lib/srp/client.rb
@@ -10,31 +10,33 @@ module SRP
     def initialize(username, password, salt = nil)
       @username = username
       @password = password
-      @salt = (salt || bigrand(4)).hex
+      @salt = salt || bigrand(4).hex
       @multiplier = multiplier # let's cache it
       calculate_verifier
     end
 
-    def authenticate(server, username, password)
-      x = calculate_x(username, password)
+    def authenticate(server)
       a = bigrand(32).hex
       aa = modpow(GENERATOR, a) # A = g^a (mod N)
-      bb = server.handshake(username, aa)
+      bb = server.handshake(@username, aa)
       u = calculate_u(aa, bb)
-      client_s = calculate_client_s(x, a, bb, u)
+      client_s = calculate_client_s(private_key, a, bb, u)
       server.validate(calculate_m(aa, bb, client_s))
     end
 
     protected
+
     def calculate_verifier
-      x = calculate_x
-      @verifier = modpow(GENERATOR, x)
-      @verifier
+      @verifier ||= modpow(GENERATOR, private_key)
+    end
+
+    def private_key
+      @private_key ||= calculate_private_key
     end
 
-    def calculate_x(username = @username, password = @password)
+    def calculate_private_key
       shex = '%x' % [@salt]
-      inner = sha256_str([username, password].join(':'))
+      inner = sha256_str([@username, @password].join(':'))
       sha256_hex(shex, inner).hex
     end