aes_ctr.rb in rmega-0.2.0

- old
+ new
@@ -1,94 +1,25 @@
-require 'rmega/utils'
-require 'rmega/crypto/aes'
-
 module Rmega
   module Crypto
     module AesCtr
-      extend self
-
-      def decrypt(key, nonce, data)
-        raise "invalid nonce" if nonce.size != 4 or !nonce.respond_to?(:pack)
-        raise "invalid key" if key.size != 4 or !key.respond_to?(:pack)
-
-        nonce = nonce.dup
-
-        mac = [nonce[0], nonce[1], nonce[0], nonce[1]]
-        enc = nil
-        a32 = Utils.str_to_a32 data
-        len = a32.size - 3
-        last_i = 0
-
-        (0..len).step(4) do |i|
-          enc = Aes.encrypt key, nonce
-          4.times do |m|
-            a32[i+m] = (a32[i+m] || 0) ^ (enc[m] || 0)
-            mac[m] = (mac[m] || 0) ^ (a32[i+m] || 0)
-          end
-          mac = Aes.encrypt key, mac
-          nonce[3] += 1
-          nonce[2] += 1 if nonce[3] == 0
-          last_i = i + 4
-        end
-
-        if last_i < a32.size
-          v = [0, 0, 0, 0]
-          (last_i..a32.size - 1).step(1) { |m| v[m-last_i] = a32[m] || 0 }
-
-          enc = Aes.encrypt key, nonce
-          4.times { |m| v[m] = v[m] ^ enc[m] }
-
-          j = data.size & 15
-          m = Utils.str_to_a32 Array.new(j+1).join(255.chr)+Array.new(17-j).join(0.chr)
-
-          4.times { |x| mac[x] = mac[x] ^ (v[x] & m[x]) }
-
-          mac = Aes.encrypt key, mac
-
-          (last_i..a32.size - 1).step(1) { |j| a32[j] = v[j - last_i] || 0 }
-        end
-
-        decrypted_data = Utils.a32_to_str(a32, data.size)
-
-        {data: decrypted_data, mac: mac}
+      def aes_ctr_cipher
+        OpenSSL::Cipher::AES.new(128, :CTR)
       end
 
-      def encrypt(key, nonce, data)
-        raise "invalid nonce" if nonce.size != 4 or !nonce.respond_to?(:pack)
-        raise "invalid key" if key.size != 4 or !key.respond_to?(:pack)
-
-        ctr = nonce.dup
-        mac = [ctr[0], ctr[1], ctr[0], ctr[1]]
-        ab32 = Utils.str_to_a32 data
-        len = ab32.size - 3
-        enc = nil
-        last_i = 0
-
-        (0..len).step(4) do |i|
-          4.times { |x| mac[x] = mac[x] ^ (ab32[i+x] || 0) }
-          mac = Aes.encrypt key, mac
-          enc = Aes.encrypt key, ctr
-          4.times { |x|  ab32[i+x] = (ab32[i+x] || 0) ^ (enc[x] || 0) }
-          ctr[3] += 1
-          ctr[2] += 1 if ctr[3].zero?
-          last_i = i + 4
-        end
-
-        i = last_i
-
-        if i < ab32.size
-          v = [0, 0, 0, 0]
-          (i..ab32.size - 1).step(1) { |j| v[j - i] = ab32[j] || 0 }
-          4.times { |x| mac[x] = mac[x] ^ v[x] }
-          mac = Aes.encrypt key, mac
-          enc = Aes.encrypt key, ctr
-          4.times { |x| v[x] = v[x] ^ enc[x] }
-          (i..ab32.size - 1).step(1) { |j| ab32[j] = v[j - i] || 0 }
-        end
-
-        decrypted_data = Utils.a32_to_str ab32, data.size
-        {data: decrypted_data, mac: mac}
+      def aes_ctr_decrypt(key, data, iv)
+        cipher = aes_ctr_cipher
+        cipher.decrypt
+        cipher.iv = iv
+        cipher.key = key
+        return cipher.update(data) + cipher.final
       end
 
+      def aes_ctr_encrypt(key, data, iv)
+        cipher = aes_ctr_cipher
+        cipher.encrypt
+        cipher.iv = iv
+        cipher.key = key
+        return cipher.update(data) + cipher.final
+      end
     end
   end
 end