feat: add p/demo/entropy

examples/gno.land/p/demo/entropy/entropy.gno

@@ -0,0 +1,85 @@
+// Entropy generates fully deterministic, cost-effective, and hard to guess
+// numbers.
+//
+// It is designed both for for single-usage, like seeding math/rand or for being
+// reused which increases the entropy and its cost effectiveness.
+//
+// Disclaimer: this package is unsafe and won't prevent others to guess values
+// in advance.
+//
+// It uses the Bernstein's hash djb2 to be CPU-cycle efficient.
+package entropy
+
+import (
+ "std"
+ "time"
+)
+
+type Instance struct {
+ value int64
+}
+
+func New() *Instance {
+ r := Instance{value: 5381}
+ r.addEntropy()
+ return &r
+}
+
+func FromSeed(seed int64) *Instance {
+ r := Instance{value: seed}
+ r.addEntropy()
+ return &r
+}
+
+func (i *Instance) Seed() int64 {
+ return i.value
+}
+
+func (i *Instance) djb2String(input string) {
+ for _, c := range input {
+ i.djb2Int64(int64(c))
+ }
+}
+
+// super fast random algorithm.
+// http://www.cse.yorku.ca/~oz/hash.html
+func (i *Instance) djb2Int64(input int64) {
+ i.value = (i.value << 5) + i.value + input
+}
+
+// AddEntropy uses various runtime variables to add entropy to the existing seed.
+func (i *Instance) addEntropy() {
+ // FIXME: reapply the 5381 initial value?
+
+ // inherit previous entropy
+ // nothing to do
+
+ // handle callers
+ {
+ caller1 := std.GetCallerAt(1).String()
+ i.djb2String(caller1)
+ caller2 := std.GetCallerAt(2).String()
+ i.djb2String(caller2)
+ }
+
+ // height
+ {
+ height := std.GetHeight()
+ i.djb2Int64(height)
+ }
+
+ // time
+ {
+ secs := time.Now().Second()
+ i.djb2Int64(int64(secs))
+ nsecs := time.Now().Nanosecond()
+ i.djb2Int64(int64(nsecs))
+ }
+
+ // FIXME: compute other hard-to-guess but deterministic variables, like real gas?
+}
+
+func (i *Instance) Value() int64 {
+ i.addEntropy()
+ return i.value
+}

examples/gno.land/p/demo/entropy/entropy_test.gno

@@ -0,0 +1,46 @@
+package entropy
+
+import (
+ "std"
+ "strconv"
+ "testing"
+)
+
+func TestInstance(t *testing.T) {
+ instance := New()
+ if instance == nil {
+ t.Errorf("instance should not be nil")
+ }
+}
+
+func TestInstanceValue(t *testing.T) {
+ baseEntropy := New()
+ baseResult := computeValue(t, baseEntropy)
+
+ sameHeightEntropy := New()
+ sameHeightResult := computeValue(t, sameHeightEntropy)
+
+ if baseResult != sameHeightResult {
+ t.Errorf("should have the same result: new=%s, base=%s", sameHeightResult, baseResult)
+ }
+
+ std.TestSkipHeights(1)
+ differentHeightEntropy := New()
+ differentHeightResult := computeValue(t, differentHeightEntropy)
+
+ if baseResult == differentHeightResult {
+ t.Errorf("should have different result: new=%s, base=%s", differentHeightResult, baseResult)
+ }
+}
+
+func computeValue(t *testing.T, r *Instance) string {
+ t.Helper()
+
+ out := ""
+ for i := 0; i < 10; i++ {
+ val := int(r.Value())
+ out += strconv.Itoa(val) + " "
+ }
+
+ return out
+}

examples/gno.land/p/demo/entropy/gno.mod

@@ -0,0 +1 @@
+module gno.land/p/demo/entropy

examples/gno.land/p/demo/entropy/z_filetest.gno

@@ -0,0 +1,56 @@
+package main
+
+import (
+ "std"
+
+ "gno.land/p/demo/entropy"
+)
+
+func main() {
+ // initial
+ println("---")
+ r := entropy.New()
+ println(r.Value())
+ println(r.Value())
+ println(r.Value())
+ println(r.Value())
+ println(r.Value())
+
+ // should be the same
+ println("---")
+ r = entropy.New()
+ println(r.Value())
+ println(r.Value())
+ println(r.Value())
+ println(r.Value())
+ println(r.Value())
+
+ std.TestSkipHeights(1)
+ println("---")
+ r = entropy.New()
+ println(r.Value())
+ println(r.Value())
+ println(r.Value())
+ println(r.Value())
+ println(r.Value())
+}
+
+// Output:
+// ---
+// 2206404796634629535
+// 6369783909128776508
+// -273967328977352263
+// 3685013872379606294
+// -321443877504368301
+// ---
+// 2206404796634629535
+// 6369783909128776508
+// -273967328977352263
+// 3685013872379606294
+// -321443877504368301
+// ---
+// 2389594832880495019
+// 2483785090669486254
+// 902493904282098385
+// 5349860799650907156
+// 3037689170578704503

examples/gno.land/r/demo/art/gnoface/gno.mod

@@ -1,3 +1,6 @@
 module gno.land/r/demo/art/gnoface
 
-require gno.land/p/demo/ufmt v0.0.0-latest
+require (
+ gno.land/p/demo/entropy v0.0.0-latest
+ gno.land/p/demo/ufmt v0.0.0-latest
+)

examples/gno.land/r/demo/art/gnoface/gnoface.gno

@@ -2,15 +2,15 @@ package gnoface
 
 import (
  "math/rand"
- "std"
  "strconv"
  "strings"
 
+ "gno.land/p/demo/entropy"
  "gno.land/p/demo/ufmt"
 )
 
 func Render(path string) string {
- seed := uint64(std.GetHeight())
+ seed := uint64(entropy.New().Value())
 
  path = strings.TrimSpace(path)
  if path != "" {