minor optimizations to fast generate, split, readme

Signed-off-by: Matt Hamilton <m@tthamilton.com>

README.md

@@ -31,13 +31,13 @@ Namely, `sync.Pool`s are used to reduce memory allocations and [frand](https://g
 The benchmarks below show an approximate 2x speed increase while maintaining the cryptographic security of key generation.
 
 ```
-% go test -bench=.
+% go test -bench=. -benchtime=3s
 goos: linux
 goarch: amd64
 pkg: github.com/eriner/vanity-npub
 cpu: AMD Ryzen 7 2700X Eight-Core Processor         
-BenchmarkGeneratePrivateKey-16        	 499538	     2073 ns/op
-BenchmarkGenerateFastPrivateKey-16    	1085912	     1146 ns/op
+BenchmarkGeneratePrivateKey-16        	1671508	     2076 ns/op
+BenchmarkGenerateFastPrivateKey-16    	3191943	     1107 ns/op
 PASS
-ok  	github.com/eriner/vanity-npub	3.240s
+ok  	github.com/eriner/vanity-npub	10.318s
 ```

fast_generate.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"encoding/hex"
+	"io"
+	"math/big"
+	"sync"
+
+	"github.com/btcsuite/btcd/btcec/v2"
+	"lukechampine.com/frand"
+)
+
+var params = btcec.S256().Params()
+var one = new(big.Int).SetInt64(1)
+var poolBytes = sync.Pool{New: func() any { return [256/8 + 8]byte{} }}
+var poolBigInt = sync.Pool{New: func() any { return new(big.Int) }}
+
+func GenerateFastPrivateKey() string {
+	b := poolBytes.Get().([256/8 + 8]byte)
+	if _, err := io.ReadFull(frand.Reader, b[:]); err != nil {
+		return ""
+	}
+	k := poolBigInt.Get().(*big.Int).SetBytes(b[:])
+	n := poolBigInt.Get().(*big.Int).Sub(params.N, one)
+	k.Mod(k, n)
+	k.Add(k, one)
+	poolBytes.Put(b)
+	poolBigInt.Put(k)
+	poolBigInt.Put(n)
+	return hex.EncodeToString(k.Bytes())
+}

main.go

@@ -3,21 +3,15 @@ package main
 
 import (
 	"context"
-	"encoding/hex"
 	"fmt"
-	"io"
 	"log"
-	"math/big"
 	"os"
 	"runtime"
 	"strings"
-	"sync"
 	"time"
 
-	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/nbd-wtf/go-nostr"
 	"github.com/nbd-wtf/go-nostr/nip19"
-	"lukechampine.com/frand"
 )
 
 func main() {
@@ -49,8 +43,8 @@ func main() {
 			case <-ctx.Done():
 				return
 			default:
-				i++ // race, but no big deal
-				sk := GenerateFastPrivateKey()
+				i++                            // race, but no big deal
+				sk := GenerateFastPrivateKey() // custom implementation (with CSPRNG) w/ ~+100% performance
 				pk, _ := nostr.GetPublicKey(sk)
 				npub, _ := nip19.EncodePublicKey(pk)
 				if strings.HasPrefix(npub, desiredPrefix) {
@@ -76,25 +70,3 @@ func main() {
 	fmt.Println(nsec)
 	fmt.Println(npub)
 }
-
-var params = btcec.S256().Params()
-var one = new(big.Int).SetInt64(1)
-var poolBytes = sync.Pool{New: func() any { return [256/8 + 8]byte{} }}
-var poolBigInt = sync.Pool{New: func() any { return new(big.Int) }}
-
-func GenerateFastPrivateKey() string {
-	b := poolBytes.Get().([256/8 + 8]byte)
-	defer poolBytes.Put(b)
-	if _, err := io.ReadFull(frand.Reader, b[:]); err != nil {
-		return ""
-	}
-	//k := new(big.Int).SetBytes(b[:])
-	//n := new(big.Int).Sub(params.N, one)
-	k := poolBigInt.Get().(*big.Int).SetBytes(b[:])
-	n := poolBigInt.Get().(*big.Int).Sub(params.N, one)
-	defer poolBigInt.Put(k)
-	defer poolBigInt.Put(n)
-	k.Mod(k, n)
-	k.Add(k, one)
-	return hex.EncodeToString(k.Bytes())
-}