1 files changed, 171 insertions, 0 deletions
diff --git a/tests/helpers/srp_helper.rb b/tests/helpers/srp_helper.rb
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+++ b/tests/helpers/srp_helper.rb
@@ -0,0 +1,171 @@
+#
+# Here are some very stripped down helper methods for SRP, useful only for
+# testing the client side.
+#
+
+require 'digest'
+require 'openssl'
+require 'securerandom'
+require 'base64'
+
+module SRP
+
+  ##
+  ## UTIL
+  ##
+
+  module Util
+    PRIME_N = <<-EOS.split.join.hex
+115b8b692e0e045692cf280b436735c77a5a9e8a9e7ed56c965f87db5b2a2ece3
+    EOS
+    BIG_PRIME_N = <<-EOS.split.join.hex # 1024 bits modulus (N)
+eeaf0ab9adb38dd69c33f80afa8fc5e86072618775ff3c0b9ea2314c9c25657
+6d674df7496ea81d3383b4813d692c6e0e0d5d8e250b98be48e495c1d6089da
+d15dc7d7b46154d6b6ce8ef4ad69b15d4982559b297bcf1885c529f566660e5
+7ec68edbc3c05726cc02fd4cbf4976eaa9afd5138fe8376435b9fc61d2fc0eb
+06e3
+    EOS
+    GENERATOR = 2 # g
+
+    def hn_xor_hg
+      byte_xor_hex(sha256_int(BIG_PRIME_N), sha256_int(GENERATOR))
+    end
+
+    # a^n (mod m)
+    def modpow(a, n, m = BIG_PRIME_N)
+      r = 1
+      while true
+        r = r * a % m if n[0] == 1
+        n >>= 1
+        return r if n == 0
+        a = a * a % m
+      end
+    end
+
+    #  Hashes the (long) int args
+    def sha256_int(*args)
+      sha256_hex(*args.map{|a| "%02x" % a})
+    end
+
+    #  Hashes the hex args
+    def sha256_hex(*args)
+      h = args.map{|a| a.length.odd? ? "0#{a}" : a }.join('')
+      sha256_str([h].pack('H*'))
+    end
+
+    def sha256_str(s)
+      Digest::SHA2.hexdigest(s)
+    end
+
+    def bigrand(bytes)
+      OpenSSL::Random.random_bytes(bytes).unpack("H*")[0]
+    end
+
+    def multiplier
+      @muliplier ||= calculate_multiplier
+    end
+
+    protected
+
+    def calculate_multiplier
+      sha256_int(BIG_PRIME_N, GENERATOR).hex
+    end
+
+    def byte_xor_hex(a, b)
+      a = [a].pack('H*')
+      b = [b].pack('H*')
+      a.bytes.each_with_index.map do |a_byte, i|
+        (a_byte ^ (b[i].ord || 0)).chr
+      end.join
+    end
+  end
+
+  ##
+  ## SESSION
+  ##
+
+  class Session
+    include SRP::Util
+    attr_accessor :user
+    attr_accessor :bb
+
+    def initialize(user, aa=nil)
+      @user = user
+      @a = bigrand(32).hex
+    end
+
+    def m
+      @m ||= sha256_hex(n_xor_g_long, login_hash, @user.salt.to_s(16), aa, bb, k)
+    end
+
+    def aa
+      @aa ||= modpow(GENERATOR, @a).to_s(16) # A = g^a (mod N)
+    end
+
+    protected
+
+    # client: K = H( (B - kg^x) ^ (a + ux) )
+    def client_secret
+      base = bb.hex
+      base -= modpow(GENERATOR, @user.private_key) * multiplier
+      base = base % BIG_PRIME_N
+      modpow(base, @user.private_key * u.hex + @a)
+    end
+
+    def k
+      @k ||= sha256_int(client_secret)
+    end
+
+    def n_xor_g_long
+      @n_xor_g_long ||= hn_xor_hg.bytes.map{|b| "%02x" % b.ord}.join
+    end
+
+    def login_hash
+      @login_hash ||= sha256_str(@user.username)
+    end
+
+    def u
+      @u ||= sha256_hex(aa, bb)
+    end
+  end
+
+  ##
+  ## Dummy USER
+  ##
+
+  class User
+    include SRP::Util
+
+    attr_accessor :username, :password, :salt, :verifier, :id, :session_token, :ok, :deleted
+
+    def initialize
+      @username = "test_user_" + SecureRandom.urlsafe_base64(10).downcase.gsub(/[_-]/, '')
+      @password = "password_" + SecureRandom.urlsafe_base64(10)
+      @salt     = bigrand(4).hex
+      @verifier = modpow(GENERATOR, private_key)
+      @ok       = false
+      @deleted  = false
+    end
+
+    def private_key
+      @private_key ||= calculate_private_key
+    end
+
+    def to_params
+      {
+        'user[login]' => @username,
+        'user[password_verifier]' => @verifier.to_s(16),
+        'user[password_salt]' => @salt.to_s(16)
+      }
+    end
+
+    private
+
+    def calculate_private_key
+      shex = '%x' % [@salt]
+      inner = sha256_str([@username, @password].join(':'))
+      sha256_hex(shex, inner).hex
+    end
+  end
+
+end