SSH verification in Go

ssh-verify.go

package main

import (
	"bytes"
	"os"

	"github.com/rs/zerolog/log"
	"golang.org/x/crypto/ssh"
)

var (
	SSHBasePath    = os.Getenv("HOME") + "/.ssh"
	PublicKeyPath  = SSHBasePath + "/id_ed25519.pub"
	PrivateKeyPath = SSHBasePath + "/id_ed25519"
)

// readAndParsePublicKey reads and parses the public key.
func readAndParsePublicKey() ssh.PublicKey {
	keyBytes, err := os.ReadFile(PublicKeyPath)
	if err != nil {
		log.Fatal().Err(err).Msg("Failed to read public key file")
	}
	pubKey, _, _, _, err := ssh.ParseAuthorizedKey(keyBytes)
	if err != nil {
		log.Fatal().Err(err).Msg("Failed to parse public key")
	}
	return pubKey
}

// readAndParsePrivateKey reads and parses the private key.
func readAndParsePrivateKey() ssh.Signer {
	keyBytes, err := os.ReadFile(PrivateKeyPath)
	if err != nil {
		log.Fatal().Err(err).Msg("Failed to read private key file")
	}
	signer, err := ssh.ParsePrivateKey(keyBytes)
	if err != nil {
		log.Fatal().Err(err).Msg("Failed to parse private key")
	}
	return signer
}

func main() {
	var pubKey ssh.PublicKey = readAndParsePublicKey()
	var privKey ssh.Signer = readAndParsePrivateKey()

	if pubKey == nil || privKey == nil {
		log.Fatal().Msg("Failed to read or parse keys")
	}

	// Verify that the private key matches the public key
	if !bytes.Equal(pubKey.Marshal(), privKey.PublicKey().Marshal()) {
		log.Fatal().Msg("Public and private keys do not match")
	}

	log.Info().Msg("Public and private keys match")
}