sops-nix/pkgs/ssh-pubkey-to-age/main.go
2021-09-24 12:09:53 +02:00

74 lines
1.7 KiB
Go

package main
import (
"bufio"
"crypto/ed25519"
"errors"
"fmt"
"os"
"strings"
"filippo.io/edwards25519"
"github.com/Mic92/sops-nix/pkgs/bech32"
"golang.org/x/crypto/ssh"
)
func ed25519PublicKeyToCurve25519(pk ed25519.PublicKey) ([]byte, error) {
// See https://blog.filippo.io/using-ed25519-keys-for-encryption and
// https://pkg.go.dev/filippo.io/edwards25519#Point.BytesMontgomery.
p, err := new(edwards25519.Point).SetBytes(pk)
if err != nil {
return nil, err
}
return p.BytesMontgomery(), nil
}
func main() {
if len(os.Args) != 1 {
println("Usage: " + os.Args[0])
println("Pipe a SSH public key or the output of ssh-keyscan into it")
os.Exit(1)
}
scanner := bufio.NewScanner(os.Stdin)
for scanner.Scan() {
text := scanner.Text() + "\n"
var err error
var pk ssh.PublicKey
if strings.HasPrefix(text, "ssh-") {
pk, _, _, _, err = ssh.ParseAuthorizedKey([]byte(text))
} else {
_, _, pk, _, _, err = ssh.ParseKnownHosts([]byte(text))
}
if err != nil {
panic(err)
}
// We only care about ed25519
if pk.Type() != ssh.KeyAlgoED25519 {
continue
}
// Get the bytes
cpk, ok := pk.(ssh.CryptoPublicKey)
if !ok {
panic(errors.New("pk does not implement ssh.CryptoPublicKey"))
}
epk, ok := cpk.CryptoPublicKey().(ed25519.PublicKey)
if !ok {
panic(errors.New("unexpected public key type"))
}
// Convert the key to curve ed25519
mpk, err := ed25519PublicKeyToCurve25519(epk)
if err != nil {
panic(fmt.Errorf("invalid Ed25519 public key: %v", err))
}
// Encode the key
s, err := bech32.Encode("age", mpk)
if err != nil {
panic(err)
}
fmt.Println(s)
}
if err := scanner.Err(); err != nil {
panic(err)
}
}