allow generation of keys in openssh format

cmd/gokey/gokeycmd/main.go

@@ -16,15 +16,16 @@ import (
 )
 
 var (
-	pass, passFile, keyType, seedPath, realm, output string
-	unsafe                                           bool
-	seedSkipCount, length                            int
+	pass, passFile, keyType, formatType, seedPath, realm, output string
+	unsafe                                                       bool
+	seedSkipCount, length                                        int
 )
 
 func initFlags() {
 	flag.StringVar(&pass, "p", "", "master password (if not specified, will be asked interactively)")
 	flag.StringVar(&passFile, "P", "", "master password file (if not specified, will be asked interactively)")
 	flag.StringVar(&keyType, "t", "pass", "output type (can be pass, seed, raw, ec256, ec384, ec521, rsa2048, rsa4096, x25519, ed25519)")
+	flag.StringVar(&formatType, "f", "pem", "key output format (can be pem, openssh)")
 	flag.StringVar(&seedPath, "s", "", "path to master seed file (optional)")
 	flag.IntVar(&seedSkipCount, "skip", 0, "number of bytes to skip from master seed file (default 0)")
 	flag.StringVar(&realm, "r", "", "password/key realm (most probably purpose of the password/key)")
@@ -73,7 +74,14 @@ func genKey(seed []byte, w io.Writer) {
 		log.Fatalln(err)
 	}
 
-	err = gokey.EncodeToPem(key, w)
+	switch formatType {
+	case "pem":
+		err = gokey.EncodeToPem(key, w)
+	case "openssh":
+		err = gokey.EncodeToSsh(key, w)
+	default:
+		err = fmt.Errorf("unknown format type %q", formatType)
+	}
 	if err != nil {
 		log.Fatalln(err)
 	}

go.mod

@@ -3,6 +3,6 @@ module github.com/cloudflare/gokey
 go 1.13
 
 require (
-	golang.org/x/crypto v0.17.0
-	golang.org/x/term v0.15.0
+	golang.org/x/crypto v0.29.0
+	golang.org/x/term v0.26.0
 )

go.sum

@@ -1,41 +1,73 @@
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
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 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/crypto v0.13.0/go.mod h1:y6Z2r+Rw4iayiXXAIxJIDAJ1zMW4yaTpebo8fPOliYc=
 golang.org/x/crypto v0.17.0 h1:r8bRNjWL3GshPW3gkd+RpvzWrZAwPS49OmTGZ/uhM4k=
 golang.org/x/crypto v0.17.0/go.mod h1:gCAAfMLgwOJRpTjQ2zCCt2OcSfYMTeZVSRtQlPC7Nq4=
+golang.org/x/crypto v0.19.0/go.mod h1:Iy9bg/ha4yyC70EfRS8jz+B6ybOBKMaSxLj6P6oBDfU=
+golang.org/x/crypto v0.23.0/go.mod h1:CKFgDieR+mRhux2Lsu27y0fO304Db0wZe70UKqHu0v8=
+golang.org/x/crypto v0.29.0 h1:L5SG1JTTXupVV3n6sUqMTeWbjAyfPwoda2DLX8J8FrQ=
+golang.org/x/crypto v0.29.0/go.mod h1:+F4F4N5hv6v38hfeYwTdx20oUvLLc+QfrE9Ax9HtgRg=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/mod v0.12.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/mod v0.15.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/mod v0.17.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
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+golang.org/x/net v0.15.0/go.mod h1:idbUs1IY1+zTqbi8yxTbhexhEEk5ur9LInksu6HrEpk=
+golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
+golang.org/x/net v0.25.0/go.mod h1:JkAGAh7GEvH74S6FOH42FLoXpXbE/aqXSrIQjXgsiwM=
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+golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
+golang.org/x/sync v0.6.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
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 golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
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+golang.org/x/tools v0.13.0/go.mod h1:HvlwmtVNQAhOuCjW7xxvovg8wbNq7LwfXh/k7wXUl58=
+golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d/go.mod h1:aiJjzUbINMkxbQROHiO6hDPo2LHcIPhhQsa9DLh0yGk=
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gokey.go

@@ -13,6 +13,7 @@ import (
 	"io"
 
 	"golang.org/x/crypto/ed25519"
+	"golang.org/x/crypto/ssh"
 )
 
 func getReader(password, realm string, seed []byte, allowUnsafe bool) (io.Reader, error) {
@@ -138,3 +139,11 @@ func EncodeToPem(key crypto.PrivateKey, w io.Writer) error {
 
 	return fmt.Errorf("unable to encode key type %T", key)
 }
+
+func EncodeToSsh(key crypto.PrivateKey, w io.Writer) error {
+	block, err := ssh.MarshalPrivateKey(key, "")
+	if err != nil {
+		return fmt.Errorf("unable to encode key type %T as ssh: %w", key, err)
+	}
+	return pem.Encode(w, block)
+}

gokey_test.go

@@ -176,6 +176,31 @@ func TestGetKey(t *testing.T) {
 	}
 }
 
+func TestGetSshKey(t *testing.T) {
+	for _, kt := range []KeyType{
+		EC256,
+		EC384,
+		EC521,
+		RSA2048,
+		RSA4096,
+		// X25519, // not supported by ssh
+		ED25519,
+	} {
+		t.Run(kt.String(), func(t *testing.T) {
+			// Due to random check bytes in the ssh key format, we can't check for stability of the output, but we can at least check that we get output.
+			key, err := GetKey("pass1", "example.com", nil, kt, true)
+			if err != nil {
+				t.Fatal(err)
+			}
+			buf := bytes.NewBuffer(nil)
+			err = EncodeToSsh(key, buf)
+			if err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+}
+
 func TestGetKeyUnsafe(t *testing.T) {
 	_, err := GetKey("pass1", "example.com", nil, EC256, false)
 	if err == nil {