#51 crypto system

lockbox/mac/hmac.lua

@@ -0,0 +1,85 @@
+local Bit = require("lockbox.util.bit");
+local Stream = require("lockbox.util.stream");
+local Array = require("lockbox.util.array");
+
+local XOR = Bit.bxor;
+
+local HMAC = function()
+
+    local public = {};
+    local blockSize = 64;
+    local Digest = nil;
+    local outerPadding = {};
+    local innerPadding = {}
+    local digest;
+
+    public.setBlockSize = function(bytes)
+        blockSize = bytes;
+        return public;
+    end
+
+    public.setDigest = function(digestModule)
+        Digest = digestModule;
+        digest = Digest();
+        return public;
+    end
+
+    public.setKey = function(key)
+        local keyStream;
+
+        if(Array.size(key) > blockSize) then
+            keyStream = Stream.fromArray(Digest()
+                        .update(Stream.fromArray(key))
+                        .finish()
+                        .asBytes());
+        else
+            keyStream = Stream.fromArray(key);
+        end
+
+        outerPadding = {};
+        innerPadding = {};
+
+        for i = 1, blockSize do
+            local byte = keyStream();
+            if byte == nil then byte = 0x00; end
+            outerPadding[i] = XOR(0x5C, byte);
+            innerPadding[i] = XOR(0x36, byte);
+        end
+
+        return public;
+    end
+
+    public.init = function()
+        digest.init()
+              .update(Stream.fromArray(innerPadding));
+        return public;
+    end
+
+    public.update = function(messageStream)
+        digest.update(messageStream);
+        return public;
+    end
+
+    public.finish = function()
+        local inner = digest.finish().asBytes();
+        digest.init()
+              .update(Stream.fromArray(outerPadding))
+              .update(Stream.fromArray(inner))
+              .finish();
+
+        return public;
+    end
+
+    public.asBytes = function()
+        return digest.asBytes();
+    end
+
+    public.asHex = function()
+        return digest.asHex();
+    end
+
+    return public;
+
+end
+
+return HMAC;