commit ed04711f609bb39eb72811b84a0cc5e961bb089a
Author: Andrew Ekstedt <andrew.ekstedt@gmail.com>
Date:   Wed Dec 31 14:59:00 2014 -0800

    Initial commit.

diff --git a/const.go b/const.go
new file mode 100644
index 0000000..71d9f29
--- /dev/null
+++ b/const.go
@@ -0,0 +1,3 @@
+package keccak
+var RC = [24]uint64{0x0000000000000001, 0x0000000000008082, 0x800000000000808a, 0x8000000080008000, 0x000000000000808b, 0x0000000080000001, 0x8000000080008081, 0x8000000000008009, 0x000000000000008a, 0x0000000000000088, 0x0000000080008009, 0x000000008000000a, 0x000000008000808b, 0x800000000000008b, 0x8000000000008089, 0x8000000000008003, 0x8000000000008002, 0x8000000000000080, 0x000000000000800a, 0x800000008000000a, 0x8000000080008081, 0x8000000000008080, 0x0000000080000001, 0x8000000080008008}
+var rotc = [5][5]uint{[5]uint{0x0, 0x24, 0x3, 0x29, 0x12}, [5]uint{0x1, 0x2c, 0xa, 0x2d, 0x2}, [5]uint{0x3e, 0x6, 0x2b, 0xf, 0x3d}, [5]uint{0x1c, 0x37, 0x19, 0x15, 0x38}, [5]uint{0x1b, 0x14, 0x27, 0x8, 0xe}}
diff --git a/genconst.go b/genconst.go
new file mode 100644
index 0000000..5dc8d36
--- /dev/null
+++ b/genconst.go
@@ -0,0 +1,27 @@
+// +build ignore
+
+package main
+
+import "fmt"
+
+func main() {
+	//Round constants
+	var RC [24]uint64
+	rc := uint8(1)
+	for i := 0; i < 24; i++ {
+		for j := 0; j <= 6; j++ {
+			RC[i] |= uint64(rc&1) << (1<<uint(j) - 1)
+			rc = rc<<1 ^ 0x71&uint8(int8(rc)>>7)
+		}
+	}
+	fmt.Println("package keccak")
+	fmt.Printf("var RC = %#016v\n", RC)
+
+	var rot [5][5]uint
+	x, y := 1, 0
+	for i := 0; i < 24; i++ {
+		rot[x][y] = uint((i+1)*(i+2)/2)%64
+		x, y = y, (2*x+3*y)%5
+	}
+	fmt.Printf("var rotc = %#v\n", rot)
+}
diff --git a/keccak.go b/keccak.go
new file mode 100644
index 0000000..d50300a
--- /dev/null
+++ b/keccak.go
@@ -0,0 +1,70 @@
+package keccak
+
+// roundGeneric implements one round of the keccak-f[1600] permutation.
+func roundGeneric(a [5][5]uint64) [5][5]uint64 {
+	a = theta(a)
+	a = rho(a)
+	a = pi(a)
+	a = chi(a)
+	// Iota
+	//a[0][0] ^= RC[i]
+	return a
+}
+
+// Theta
+func theta(a [5][5]uint64) [5][5]uint64 {
+	var c [5]uint64
+	for x := range a {
+		c[x] = a[x][0] ^ a[x][1] ^ a[x][2] ^ a[x][3] ^ a[x][4]
+	}
+	for x := range a {
+		x0, x1 := (x+4)%5, (x+1)%5
+		a[x][0] ^= c[x0] ^ rotl(c[x1], 1)
+		a[x][1] ^= c[x0] ^ rotl(c[x1], 1)
+		a[x][2] ^= c[x0] ^ rotl(c[x1], 1)
+		a[x][3] ^= c[x0] ^ rotl(c[x1], 1)
+		a[x][4] ^= c[x0] ^ rotl(c[x1], 1)
+	}
+	return a
+}
+
+// Rho
+func rho(a [5][5]uint64) [5][5]uint64 {
+	for x := range a {
+		for y := range a[0] {
+			a[x][y] = rotl(a[x][y], rotc[x][y])
+		}
+	}
+	return a
+}
+
+// Pi
+func pi(a [5][5]uint64) [5][5]uint64 {
+	var b [5][5]uint64
+	for x := range a {
+		for y := range a[0] {
+			x0 := y
+			y0 := (x*2 + y*3) % 5
+			b[x0][y0] = a[x][y]
+		}
+	}
+	return b
+}
+
+// Chi
+func chi(a [5][5]uint64) [5][5]uint64 {
+	for y := range a[0] {
+		c := [5]uint64{a[0][y], a[1][y], a[2][y], a[3][y], a[4][y]}
+		a[0][y] ^= ^c[1] & c[2]
+		a[1][y] ^= ^c[2] & c[3]
+		a[2][y] ^= ^c[3] & c[4]
+		a[3][y] ^= ^c[4] & c[0]
+		a[4][y] ^= ^c[0] & c[1]
+	}
+	return a
+}
+
+func rotl(a uint64, r uint) uint64 {
+	return a<<r | a>>(64-r)
+}
+
diff --git a/keccak_test.go b/keccak_test.go
new file mode 100644
index 0000000..f75f824
--- /dev/null
+++ b/keccak_test.go
@@ -0,0 +1,29 @@
+package keccak
+
+import (
+	"reflect"
+	"testing"
+)
+
+var vector = []byte{0xc5, 0xd2, 0x46, 0x01, 0x86, 0xf7, 0x23, 0x3c,
+	0x92, 0x7e, 0x7d, 0xb2, 0xdc, 0xc7, 0x03, 0xc0,
+	0xe5, 0x00, 0xb6, 0x53, 0xca, 0x82, 0x27, 0x3b,
+	0x7b, 0xfa, 0xd8, 0x04, 0x5d, 0x85, 0xa4, 0x70,
+}
+
+func TestKeccak(t *testing.T) {
+	h := New()
+	sum := h.Sum(nil)
+	if !reflect.DeepEqual(sum, vector) {
+		t.Errorf("\"\": want % x, got % x", vector, sum)
+	}
+}
+
+func Benchmark256(b *testing.B) {
+	var tmp [Size]byte
+	h := New()
+	b.SetBytes(BlockSize)
+	for i := 0; i < b.N; i ++ {
+		h.Sum(tmp[:])
+	}
+}
diff --git a/sponge.go b/sponge.go
new file mode 100644
index 0000000..41a2cd9
--- /dev/null
+++ b/sponge.go
@@ -0,0 +1,87 @@
+package keccak
+
+import "hash"
+
+const Size = 256/8
+
+const BlockSize = 1600/8 - Size*2
+
+// digest implements hash.Hash
+type digest struct {
+	a [5][5]uint64
+	buf [BlockSize]byte
+	len int
+}
+
+func New() hash.Hash {
+	return &digest{}
+}
+
+func (d *digest) Size() int { return Size }
+func (d *digest) BlockSize() int { return BlockSize }
+
+func (d *digest) Reset() {
+	*d = digest{}
+}
+
+func (d *digest) Write(b []byte) (int, error) {
+	written := len(b)
+	for len(b) > 0 {
+		n := copy(d.buf[d.len:], b)
+		d.len += n
+		b = b[n:]
+		if d.len == BlockSize {
+			d.flush()
+		}
+	}
+	return written, nil
+}
+
+func (d *digest) flush() {
+	b := d.buf[:]
+loop:
+	for y := range d.a[0] {
+		for  x := range d.a {
+			if len(b) == 0 {
+				break loop
+			}
+			d.a[x][y] ^= uint64(b[0]) + uint64(b[1])<<8 + uint64(b[2])<<16 + uint64(b[3])<<24 + uint64(b[4])<<32 + uint64(b[5])<<40 + uint64(b[6])<<48 + uint64(b[7])<<56
+			b = b[8:]
+		}
+	}
+	d.a = keccak(d.a)
+	d.len = 0
+}
+
+func keccak(a [5][5]uint64) [5][5]uint64 {
+	for i := 0; i < 24; i++ {
+		a = roundGeneric(a)
+		a[0][0] ^= RC[i]
+	}
+	return a
+}
+
+func (d0 *digest) Sum(b []byte) []byte {
+	d := *d0
+	d.buf[d.len] = 0x01
+	for i := d.len+1; i < BlockSize; i++ {
+		d.buf[i] = 0
+	}
+	d.buf[BlockSize-1] |= 0x80
+	d.flush()
+
+	b = le64enc(b, d.a[0][0])
+	b = le64enc(b, d.a[1][0])
+	b = le64enc(b, d.a[2][0])
+	b = le64enc(b, d.a[3][0])
+	return b
+}
+
+func le64enc(b []byte, x uint64) []byte {
+	return append(b, byte(x), byte(x>>8), byte(x>>16), byte(x>>24), byte(x>>32), byte(x>>40), byte(x>>48), byte(x>>56))
+}
+
+func (d *digest) writeByte(b byte) {
+	var tmp = [1]byte{b}
+	d.Write(tmp[:])
+}