From f8b82a6eed6ae9d8706b34a893dc02595aa2539a Mon Sep 17 00:00:00 2001
From: "kayos@tcp.direct" <kayos@tcp.direct>
Date: Sat, 11 Nov 2023 14:00:52 -0800
Subject: [PATCH] init

---
 go.mod     |   3 ++
 go.sum     |   0
 shishua.go | 148 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 151 insertions(+)
 create mode 100644 go.mod
 create mode 100644 go.sum
 create mode 100644 shishua.go

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..77a27af
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.tcp.direct/kayos/shishua-go
+
+go 1.21.2
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..e69de29
diff --git a/shishua.go b/shishua.go
new file mode 100644
index 0000000..347751f
--- /dev/null
+++ b/shishua.go
@@ -0,0 +1,148 @@
+package main
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+	"encoding/hex"
+	"fmt"
+	"os"
+)
+
+type SHISHUA struct {
+	state   [16]uint64
+	output  [16]uint64
+	counter [4]uint64
+}
+
+var phi = [16]uint64{
+	0x9E3779B97F4A7C15, 0xF39CC0605CEDC834, 0x1082276BF3A27251, 0xF86C6A11D0C18E95,
+	0x2767F0B153D27B7F, 0x0347045B5BF1827F, 0x01886F0928403002, 0xC1D64BA40F335E36,
+	0xF06AD7AE9717877E, 0x85839D6EFFBD7DC6, 0x64D325D1C5371682, 0xCADD0CCCFDFFBBE1,
+	0x626E33B8D04B4331, 0xBBF73C790D94F79D, 0x471C4AB3ED3D82A5, 0xFEC507705E4AE6E5,
+}
+
+func (srng *SHISHUA) shuffle() {
+	for j := 0; j < 2; j++ {
+		s := srng.state[j*8 : (j+1)*8]
+		o := srng.output[j*4 : (j+1)*4]
+		var t [8]uint64
+
+		for k := 0; k < 4; k++ {
+			s[k+4] += srng.counter[k]
+		}
+
+		shufOffsets := []uint8{2, 3, 0, 1, 5, 6, 7, 4, 3, 0, 1, 2, 6, 7, 4, 5}
+		for k := 0; k < 8; k++ {
+			t[k] = (s[shufOffsets[k]] >> 32) | (s[shufOffsets[k+8]] << 32)
+		}
+
+		for k := 0; k < 4; k++ {
+			uLo := s[k] >> 1
+			uHi := s[k+4] >> 3
+			s[k] = uLo + t[k]
+			s[k+4] = uHi + t[k+4]
+			o[k] = uLo ^ t[k+4]
+		}
+	}
+
+	for j := 0; j < 4; j++ {
+		srng.output[j+8] = srng.state[j] ^ srng.state[j+12]
+		srng.output[j+12] = srng.state[j+8] ^ srng.state[j+4]
+		srng.counter[j] += 7 - uint64(j*2)
+	}
+}
+
+func (srng *SHISHUA) Uint64() uint64 {
+	out := srng.output[0]
+	srng.shuffle()
+	return out
+}
+
+/*
+	func (srng *SHISHUA) Seed(seed int64) {
+		srng.Seed64(uint64(seed))
+	}
+*/
+func (srng *SHISHUA) prngGen(buf []byte, size int) []byte {
+	if buf == nil {
+		panic("buf is nil")
+	}
+	for i := 0; i < size; i += 128 {
+		for j := 0; j < 16; j++ {
+			binary.LittleEndian.PutUint64(buf[i+j*8:], srng.Uint64())
+		}
+	}
+
+	return buf
+}
+
+func (srng *SHISHUA) Read(buf []byte) (n int, err error) {
+	size := cap(buf)
+	if size%128 != 0 {
+		panic("buf's size must be a multiple of 128 bytes.")
+	}
+	return copy(buf, srng.prngGen(buf, size)), nil
+}
+
+func NewSHISHUA() *SHISHUA {
+	srng := &SHISHUA{}
+
+	buf := make([]byte, 64)
+	if n, e := rand.Read(buf); n != 64 || e != nil {
+		panic("rand.Read failed")
+	}
+
+	var seed [4]uint64
+	for i := 0; i < 4; i++ {
+		seed[i] = uint64(buf[i*8+0]) | uint64(buf[i*8+1])<<8 | uint64(buf[i*8+2])<<16 | uint64(buf[i*8+3])<<24
+	}
+
+	copy(srng.state[:], phi[:])
+	for i := 0; i < 4; i++ {
+		srng.state[i*2+0] ^= seed[i]
+		srng.state[i*2+8] ^= seed[(i+2)%4]
+	}
+
+	const rounds = 13
+	for i := 0; i < rounds; i++ {
+		srng.shuffle()
+		for j := 0; j < 4; j++ {
+			srng.state[j] = srng.output[j+12]
+			srng.state[j+4] = srng.output[j+8]
+			srng.state[j+8] = srng.output[j+4]
+			srng.state[j+12] = srng.output[j]
+		}
+	}
+
+	return srng
+}
+
+func main() {
+	s := NewSHISHUA()
+
+	buf := make([]byte, 128)
+
+	var occurrences = make(map[string]struct{})
+
+	for i := 0; i < 100; i++ {
+		n, _ := s.Read(buf)
+		if n != cap(buf) {
+			panic("n != cap(buf)")
+		}
+		// spew.Dump(buf[:n])
+		str := hex.EncodeToString(buf)
+		if _, ok := occurrences[str]; ok {
+			panic("duplicate hex")
+		}
+		occurrences[str] = struct{}{}
+		_, _ = os.Stdout.WriteString(str)
+		_, _ = os.Stdout.WriteString("\n")
+	}
+
+	for i := 0; i < 5000; i++ {
+		str := fmt.Sprintf("%x", s.Uint64())
+		if _, ok := occurrences[str]; ok {
+			panic("duplicate uint64")
+		}
+	}
+}