Match public key with prefix with only bytes that matter

main.go

@@ -20,12 +20,14 @@ const b32Lower = "abcdefghijklmnopqrstuvwxyz234567"
 
 var b32Enc = base32.NewEncoding(b32Lower).WithPadding(base32.NoPadding)
 
-func generate(wg *sync.WaitGroup, prefix string) {
+func generate(wg *sync.WaitGroup, prefix string, prefixDecodedLen int) {
  for {
  publicKey, secretKey, err := ed25519.GenerateKey(nil)
  checkErr(err)
 
- publicKeyB32 := b32Enc.EncodeToString(publicKey)
+ // Match the public key with prefix.
+ // No need to encode all PK to B32 if prefix shorter
+ publicKeyB32 := b32Enc.EncodeToString(publicKey[0:prefixDecodedLen])
  // If a matching address is found, save key and notify wait group
  if strings.HasPrefix(publicKeyB32, prefix) {
  onionAddress := encodePublicKey(publicKey)
@@ -92,6 +94,19 @@ func main() {
  os.Exit(1)
  }
 
+ prefixLen := len(prefix)
+ prefixDecodedLen := b32Enc.DecodedLen(prefixLen)
+ // Same DecodedLen(prefix) but without rounding to floor
+ prefixDecodedLenRatio := float64(prefixLen) * 5.0 / 8.0
+ // if there is some division remainder
+ if prefixDecodedLenRatio > float64(prefixDecodedLen) {
+ // 8 bytes encoded into 5 chars. We must add them all because don't know which byte changes a char
+ prefixDecodedLen += 8
+ }
+ if prefixDecodedLen > 32 {
+ prefixDecodedLen = 32
+ }
+
  // Get the number of desired addresses from second argument.
  numAddresses, _ := strconv.Atoi(os.Args[2])
 
@@ -101,7 +116,7 @@ func main() {
 
  // For each CPU, run a generate goroutine
  for i := 0; i < runtime.NumCPU(); i++ {
- go generate(&wg, prefix)
+ go generate(&wg, prefix, prefixDecodedLen)
  }
 
  // Exit after the desired number of addresses have been found.