Match by a prefix instead of regexp

.gitignore

@@ -1,3 +1,4 @@
+oniongen
 
 # Created by https://www.gitignore.io/api/go
 # Edit at https://www.gitignore.io/?templates=go

Makefile

@@ -0,0 +1,4 @@
+build:
+	./make.sh build
+update_libs:
+	./make.sh update_libs

README.md

@@ -2,28 +2,33 @@
 
 v3 .onion address vanity URL generator written in Go.
 
-This implementation generates random ed25519 keys across all CPU cores. The ed25519 public key is converted to a Tor v3 .onion address which is then compared to a user supplied regex to find a vanity URL. If the regex for the .onion address matches, the secret key is expanded for use by Tor and the public key, secret key, and hostname are written to file in a new directory named for the .onion address. The program terminates when the user supplied number of addresses have been generated.
+This implementation generates random ed25519 keys across all CPU cores.
+The ed25519 public key is converted to a Tor v3 .onion address which is then compared to a user supplied prefix to find a vanity URL.
+If the prefix for the .onion address matches, the secret key is expanded for use by Tor and the public key, secret key, and hostname are written to file in a new directory named for the .onion address.
+The program terminates when the user supplied number of addresses have been generated.
 
 ## Usage
 
 ```
-go run main.go <regex> <number>
+go run main.go <prefix> <count>
 
-    regex   regex pattern addresses should match, consisiting of: A-Z, 2-7
-    number  number of matching addresses to generate before exiting
+    prefix  addresses should start from the prefix, consisiting of: a-z, 2-7
+    count   number of matching addresses to generate before exiting
 ```
 
 ## Example
 
 ```
-go run main.go "^test" 5
+go run main.go test 5
 
     generate 5 onion addresses starting with "test"
 ```
 
 ## References
-
+- Onion Addresses are defined in [Tor Rendezvous Specification - Version 3](https://github.com/torproject/torspec/blob/main/rend-spec-v3.txt)
 - public key -> onion: https://github.com/torproject/torspec/blob/12271f0e6db00dee9600425b2de063e02f19c1ee/rend-spec-v3.txt#L2136-L2158
 - secret key expansion:
-    - implementation in mkp224o: https://github.com/cathugger/mkp224o/blob/af5a7cfe122ba62e819b92c8b5a662151a284c69/ed25519/ed25519.h#L153-L161
-    - possibly related: https://github.com/torproject/torspec/blob/12271f0e6db00dee9600425b2de063e02f19c1ee/rend-spec-v3.txt#L2268-L2327 ??
+  - [specification](https://github.com/torproject/torspec/blob/12271f0e6db00dee9600425b2de063e02f19c1ee/rend-spec-v3.txt#L2268-L2327)
+  - [should the secret key be expanded?](https://tor.stackexchange.com/questions/23849/tor-onion-domain-should-the-secret-key-be-expanded)
+  - [implementation in tor](https://gitlab.torproject.org/tpo/core/tor/-/blob/main/src/ext/ed25519/donna/ed25519_tor.c#L65)
+  - [implementation in mkp224o](https://github.com/cathugger/mkp224o/blob/af5a7cfe122ba62e819b92c8b5a662151a284c69/ed25519/ed25519.h#L153-L161)

go.mod

@@ -1,8 +1,8 @@
 module github.com/rdkr/oniongen-go
 
-go 1.14
+go 1.18
 
 require (
-	golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad
-	golang.org/x/sys v0.0.0-20201223074533-0d417f636930 // indirect
+	golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d
+	golang.org/x/sys v0.0.0-20220624220833-87e55d714810 // indirect
 )

go.sum

@@ -1,10 +1,4 @@
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad h1:DN0cp81fZ3njFcrLCytUHRSUkqBjfTo4Tx9RJTWs0EY=
-golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad/go.mod h1:jdWPYTVW3xRLrWPugEBEK3UY2ZEsg3UU495nc5E+M+I=
-golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20201223074533-0d417f636930 h1:vRgIt+nup/B/BwIS0g2oC0haq0iqbV3ZA+u6+0TlNCo=
-golang.org/x/sys v0.0.0-20201223074533-0d417f636930/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d h1:sK3txAijHtOK88l68nt020reeT1ZdKLIYetKl95FzVY=
+golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
+golang.org/x/sys v0.0.0-20220624220833-87e55d714810 h1:rHZQSjJdAI4Xf5Qzeh2bBc5YJIkPFVM6oDtMFYmgws0=
+golang.org/x/sys v0.0.0-20220624220833-87e55d714810/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

main.go

@@ -6,7 +6,6 @@ import (
 	"crypto/sha512"
 	"encoding/base32"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"regexp"
 	"runtime"
@@ -17,17 +16,21 @@ import (
 	"golang.org/x/crypto/sha3"
 )
 
-func generate(wg *sync.WaitGroup, re *regexp.Regexp) {
+const b32Lower = "abcdefghijklmnopqrstuvwxyz234567"
 
-	for {
+var b32Enc = base32.NewEncoding(b32Lower).WithPadding(base32.NoPadding)
 
+func generate(wg *sync.WaitGroup, prefix string, prefixDecodedLen int) {
+	for {
 		publicKey, secretKey, err := ed25519.GenerateKey(nil)
 		checkErr(err)
 
-		onionAddress := encodePublicKey(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 re.MatchString(onionAddress) == true {
+		if strings.HasPrefix(publicKeyB32, prefix) {
+			onionAddress := encodePublicKey(publicKey)
 			fmt.Println(onionAddress)
 			save(onionAddress, publicKey, expandSecretKey(secretKey))
 			wg.Done()
@@ -36,45 +39,42 @@ func generate(wg *sync.WaitGroup, re *regexp.Regexp) {
 }
 
 func expandSecretKey(secretKey ed25519.PrivateKey) [64]byte {
-
 	hash := sha512.Sum512(secretKey[:32])
+	// clamp the blinding factor 'h' according to the ed25519 spec
 	hash[0] &= 248
 	hash[31] &= 127
 	hash[31] |= 64
 	return hash
-
 }
 
 func encodePublicKey(publicKey ed25519.PublicKey) string {
-
 	// checksum = H(".onion checksum" || pubkey || version)
 	var checksumBytes bytes.Buffer
 	checksumBytes.Write([]byte(".onion checksum"))
-	checksumBytes.Write([]byte(publicKey))
+	checksumBytes.Write(publicKey)
 	checksumBytes.Write([]byte{0x03})
 	checksum := sha3.Sum256(checksumBytes.Bytes())
 
 	// onion_address = base32(pubkey || checksum || version)
 	var onionAddressBytes bytes.Buffer
-	onionAddressBytes.Write([]byte(publicKey))
-	onionAddressBytes.Write([]byte(checksum[:2]))
+	onionAddressBytes.Write(publicKey)
+	onionAddressBytes.Write(checksum[:2])
 	onionAddressBytes.Write([]byte{0x03})
-	onionAddress := base32.StdEncoding.EncodeToString(onionAddressBytes.Bytes())
-
-	return strings.ToLower(onionAddress)
+	onionAddress := b32Enc.EncodeToString(onionAddressBytes.Bytes())
 
+	return onionAddress
 }
 
 func save(onionAddress string, publicKey ed25519.PublicKey, secretKey [64]byte) {
-	os.MkdirAll(onionAddress, 0700)
+	checkErr(os.MkdirAll(onionAddress, 0700))
 
 	secretKeyFile := append([]byte("== ed25519v1-secret: type0 ==\x00\x00\x00"), secretKey[:]...)
-	checkErr(ioutil.WriteFile(onionAddress+"/hs_ed25519_secret_key", secretKeyFile, 0600))
+	checkErr(os.WriteFile(onionAddress+"/hs_ed25519_secret_key", secretKeyFile, 0600))
 
 	publicKeyFile := append([]byte("== ed25519v1-public: type0 ==\x00\x00\x00"), publicKey...)
-	checkErr(ioutil.WriteFile(onionAddress+"/hs_ed25519_public_key", publicKeyFile, 0600))
+	checkErr(os.WriteFile(onionAddress+"/hs_ed25519_public_key", publicKeyFile, 0600))
 
-	checkErr(ioutil.WriteFile(onionAddress+"/hostname", []byte(onionAddress+".onion\n"), 0600))
+	checkErr(os.WriteFile(onionAddress+"/hostname", []byte(onionAddress+".onion\n"), 0600))
 }
 
 func checkErr(err error) {
@@ -84,14 +84,30 @@ func checkErr(err error) {
 }
 
 func main() {
-
 	// Set runtime to use all available CPUs.
 	runtime.GOMAXPROCS(runtime.NumCPU())
 
-	// Compile regex from first argument.
-	re, _ := regexp.Compile(os.Args[1])
+	prefix := os.Args[1]
+	validPrefix, _ := regexp.MatchString(`^[a-z2-9]*$`, prefix)
+	if !validPrefix {
+		fmt.Fprintf(os.Stderr, "Invalid prefix: onion addresses can't contain 0 or 1 to avoid confusion with o and l\n")
+		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 addreses from second argument.
+	// Get the number of desired addresses from second argument.
 	numAddresses, _ := strconv.Atoi(os.Args[2])
 
 	// WaitGroup of size equal to desired number of addresses
@@ -100,10 +116,9 @@ func main() {
 
 	// For each CPU, run a generate goroutine
 	for i := 0; i < runtime.NumCPU(); i++ {
-		go generate(&wg, re)
+		go generate(&wg, prefix, prefixDecodedLen)
 	}
 
 	// Exit after the desired number of addresses have been found.
 	wg.Wait()
-
 }

make.sh

@@ -0,0 +1,32 @@
+build() {
+  go mod download
+  GOAMD64=v3 go build -tags release -o ./oniongen
+}
+
+update_libs() {
+  go get -u
+  go mod tidy
+}
+
+help() {
+  go get -u
+  echo "build update_libs"
+}
+
+progname=$(basename $0)
+subcommand=$1
+case $subcommand in
+    "" | "-h" | "--help")
+        help
+        ;;
+    *)
+        shift
+        echo "Executing: $subcommand"
+        ${subcommand} "$@"
+        if [ $? = 127 ]; then
+            echo "Error: '$subcommand' is not a known subcommand." >&2
+            help
+            exit 1
+        fi
+        ;;
+esac