Entropy: improve markov map randomness, decrease detectability

go.mod

@@ -26,4 +26,5 @@ require (
 	github.com/savsgio/gotils v0.0.0-20240303185622-093b76447511 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
 	golang.org/x/sys v0.21.0 // indirect
+	nullprogram.com/x/rng v1.1.0 // indirect
 )

go.sum

@@ -51,3 +51,4 @@ golang.org/x/sys v0.21.0 h1:rF+pYz3DAGSQAxAu1CbC7catZg4ebC4UIeIhKxBZvws=
 golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 nullprogram.com/x/rng v1.1.0 h1:SMU7DHaQSWtKJNTpNFIFt8Wd/KSmOuSDPXrMFp/UMro=
+nullprogram.com/x/rng v1.1.0/go.mod h1:glGw6V87vyfawxCzqOABL3WfL95G65az9Z2JZCylCkg=

heffalump/markov.go

@@ -5,12 +5,19 @@ import (
 	"io"
 	"math/rand"
 	"strings"
+	"time"
 	"unicode"
 	"unicode/utf8"
 
+	"git.tcp.direct/kayos/common/entropy"
 	"git.tcp.direct/kayos/common/squish"
 )
 
+const (
+	sp = " "
+	nl = "\n"
+)
+
 // NewDefaultMarkovMap creates a new MarkovMap from the default source text.
 func NewDefaultMarkovMap() MarkovMap {
 	src, err := squish.UnpackStr(srcGz)
@@ -70,11 +77,15 @@ func ScanHTML(data []byte, atEOF bool) (advance int, token []byte, err error) {
 type tokenPair [2]string
 
 // MarkovMap is a map that acts as a Markov chain generator.
-type MarkovMap map[tokenPair][]string
+type MarkovMap struct {
+	m map[tokenPair][]string
+	r *rand.Rand
+}
 
 // MakeMarkovMap makes an empty MakeMarkov and fills it with r.
 func MakeMarkovMap(r io.Reader) MarkovMap {
-	m := MarkovMap{}
+	m := MarkovMap{m: make(map[tokenPair][]string)}
+	m.r = rand.New(rand.NewSource(entropy.GetOptimizedRand().Int63()))
 	m.Fill(r)
 	return m
 }
@@ -97,13 +108,13 @@ func (mm MarkovMap) Fill(r io.Reader) {
 // Add adds a three token sequence to the map.
 func (mm MarkovMap) Add(w1, w2, w3 string) {
 	p := tokenPair{w1, w2}
-	mm[p] = append(mm[p], w3)
+	mm.m[p] = append(mm.m[p], w3)
 }
 
 // Get pseudo-randomly chooses a possible suffix to w1 and w2.
 func (mm MarkovMap) Get(w1, w2 string) string {
 	p := tokenPair{w1, w2}
-	suffix, ok := mm[p]
+	suffix, ok := mm.m[p]
 	if !ok {
 		return ""
 	}
@@ -119,10 +130,15 @@ func (mm MarkovMap) Read(p []byte) (n int, err error) {
 	for {
 		w3 = mm.Get(w1, w2)
 		if n+len(w3)+1 >= len(p) {
+			n += copy(p[n:], nl)
 			break
 		}
 		n += copy(p[n:], w3)
-		n += copy(p[n:], "\n")
+		if time.Now().UnixNano()%10 == 0 {
+			n += copy(p[n:], nl)
+		} else {
+			n += copy(p[n:], sp)
+		}
 		w1, w2 = w2, w3
 	}
 	return