Merge pull request #2 from felschr/main

fix implementation & clean up

README.md

@@ -1,11 +1,8 @@
-1. I have a GPG keypair in the same format as the one provided in `test-key.asc`. It is `ed25519`.
+# gpg2age
-2. That key was used to encrypt a file with [age encryption](https://github.com/FiloSottile/age) as shown below
-3. I want to decrypt that file, but only have a GPG secret key, as I couldn't
-   find out how to derive a SSH or age key from it.
 
-**GOAL**: Derive an age key from the provided GPG key that decrypt the file as
+Derive private ed25519 SSH key from private PGP key.
-shown below. A SSH key is also enough, since it can be used with `ssh-to-age` to
+
-derive the age key.
+GPG itself only supports exporting _public_ SSH keys and other tools don't work for ed25519 keys.
 
 ##### Notes:
 
@@ -13,60 +10,47 @@ derive the age key.
 - Work on `gnupg` was started for this feature, but never finished see this
   issue and commit: https://dev.gnupg.org/T6647
 
-## Example
+## Instructions
 
-Example key provided in `test-key.asc` to be imported. Use `--homedir` with
+First you need to export your PGP key from GPG:
-`gpg` to set a temporary `.gnupg` directory
 
 ```sh
-❯ gpg --homedir ./gnupg --import test-key.asc                                                                                                                                                                          impure ❄ ssh-to-age age
+❯ gpg2 --export-secret-keys --armor test@test.test >priv-gpg
-gpg: WARNING: unsafe permissions on homedir '/home/pinpox/code/github.com/pinpox/gpg2age/./gnupg'
-gpg: key 76188CF30717B54E: public key "test (test) <test@test.com>" imported
-gpg: key 76188CF30717B54E: secret key imported
-gpg: Total number processed: 1
-gpg:               imported: 1
-gpg:       secret keys read: 1
-gpg:   secret keys imported: 1
-
-❯ gpg --homedir ./gnupg_testkey/ -K
-/home/pinpox/code/github.com/pinpox/gpg2age/./gnupg_testkey/pubring.kbx
------------------------------------------------------------------------
-sec   ed25519 2024-03-25 [C]
-      9FE4D484B69DB9F5C7AA208E76188CF30717B54E
-uid           [ultimate] test (test) <test@test.com>
-ssb   ed25519 2024-03-25 [S]
-ssb   cv25519 2024-03-25 [E]
-ssb   ed25519 2024-03-25 [A]
 ```
 
-### Get age key and encrypt test file
+Then identify the public SSH key that was used to encrypt your secret.
+You can search for your GitHub username in: https://fluence-dao.s3.eu-west-1.amazonaws.com/metadata.json
+
+If you have multiple subkeys, usually it is the authenticate key highlighted with `[A]` in the output of:
 
 ```sh
-❯ gpg --homedir ./gnupg --export-ssh-key 9FE4D484B69DB9F5C7AA208E76188CF30717B54E
+❯ gpg --list-secret-keys --with-keygrip
-ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICYvKXGcG4a19tTT0Rycbn+D0r/YlKltLJ9dY2gR/Fjx openpgp:0x47C9F3FF
 ```
 
+### Derive private SSH key
+
 ```sh
-❯ gpg --homedir ./gnupg --export-ssh-key 9FE4D484B69DB9F5C7AA208E76188CF30717B54E | ssh-to-age                                                                                                                             impure ❄ ssh-to-age
+❯ go run main.go
-age18s8m9hvlrwvltgys4lafyyqe356ntc7e06t4kd2nccqm5amsaa2s878mju # saved as age-public-key
 ```
 
+It'll ask you for the path to your private PGP key, followed by choosing the key/subkey and if your PGP key is encrypted it'll ask for the passphrase.
+
+In the output, verify that the public SSH key printed matches the one in `metadata.json`.
+If it matches, the last part of the output it will print the matching private SSH key.
+You can save the key to a file and use how you want.
+
+### Example: Decrypt age files
+
+If you want to decrypt a file that was encryptd by `age` with your public SSH key, you can just use `age` as normal to decrypt the file using the SSH private key that we've got in the previous step:
+
 ```sh
-❯ age --encrypt -R age-public-key testfile.txt > testfile.txt.age
+❯ age --decrypt --identity ./ssh-secret-key --output decrypted ./testfile.txt.age
 ```
 
-### Get secret age key
+### Support & Donations
 
-```sh
+This project was built with lots of headaches by [pinpox](https://github.com/pinpox/) & [felschr](https://github.com/felschr/). If you need help, feel free to contact us.
-❯ go run main.go                                                                                                                                                                                                       impure ❄ ssh-to-age age
-AGE-SECRET-KEY-165W948VSG5QEM0RPEUX8T3K4YXJT2WF83C2GXQH8Q3Q0ZHCTH44SSV0H34 # saved as age-secret-key
-```
 
-### Try to decrypt
+And if you want to thank us, you can send us any crypto or token to our Ethereum / Polygon wallets 😊:  
-```sh
+pinpox: `0x3d479e19ae8d1a67becdaeaf8d2d37c8e425bd03`
-❯ age --decrypt --identity age-secret-key --output decrypted testfile.txt.age                                                                                                                                          impure ❄ ssh-to-age age
+felschr: `0xD66753D737603E18018281E298Df86DE402d313E`
-age: error: no identity matched any of the recipients
-age: report unexpected or unhelpful errors at https://filippo.io/age/report
-```
-
-FAIL :(

go.mod

@@ -3,9 +3,7 @@ module gpg2age
 go 1.21.8
 
 require (
-	github.com/Mic92/ssh-to-age v0.0.0-20240304065525-796b05d6e3b3
 	github.com/ProtonMail/go-crypto v1.0.0
-	github.com/davecgh/go-spew v1.1.1
 	golang.org/x/crypto v0.20.0
 	golang.org/x/term v0.18.0
 )

go.sum

@@ -1,13 +1,9 @@
-github.com/Mic92/ssh-to-age v0.0.0-20240304065525-796b05d6e3b3 h1:YT+DB0TTQ/Li1AQOAAP20k2kCT3XndzsprKgTg5GCIc=
-github.com/Mic92/ssh-to-age v0.0.0-20240304065525-796b05d6e3b3/go.mod h1:M/OUOt0/3WI/tYzEYBhQNyU5OB1YStcJEkUaTDnjxJI=
 github.com/ProtonMail/go-crypto v1.0.0 h1:LRuvITjQWX+WIfr930YHG2HNfjR1uOfyf5vE0kC2U78=
 github.com/ProtonMail/go-crypto v1.0.0/go.mod h1:EjAoLdwvbIOoOQr3ihjnSoLZRtE8azugULFRteWMNc0=
 github.com/bwesterb/go-ristretto v1.2.3/go.mod h1:fUIoIZaG73pV5biE2Blr2xEzDoMj7NFEuV9ekS419A0=
 github.com/cloudflare/circl v1.3.3/go.mod h1:5XYMA4rFBvNIrhs50XuiBJ15vF2pZn4nnUKZrLbUZFA=
 github.com/cloudflare/circl v1.3.7 h1:qlCDlTPz2n9fu58M0Nh1J/JzcFpfgkFHHX3O35r5vcU=
 github.com/cloudflare/circl v1.3.7/go.mod h1:sRTcRWXGLrKw6yIGJ+l7amYJFfAXbZG0kBSc8r4zxgA=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=

main.go

@@ -1,33 +1,22 @@
 package main
 
 import (
-	"crypto/sha512"
+	"encoding/pem"
 	"fmt"
 	"log"
 	"os"
-  "syscall"
+	"syscall"
-	"strings"
-  "encoding/pem"
 
 	"github.com/ProtonMail/go-crypto/openpgp"
 	"github.com/ProtonMail/go-crypto/openpgp/armor"
-  "github.com/ProtonMail/go-crypto/openpgp/eddsa"
+	"github.com/ProtonMail/go-crypto/openpgp/eddsa"
 	"github.com/ProtonMail/go-crypto/openpgp/packet"
 
 	"crypto/ed25519"
 	"errors"
-	"github.com/Mic92/ssh-to-age/bech32"
-	"github.com/davecgh/go-spew/spew"
-  "golang.org/x/term"
-	"golang.org/x/crypto/curve25519"
 	"golang.org/x/crypto/ssh"
-	// "bytes"
+	"golang.org/x/term"
-	// "golang.org/x/crypto/ssh"
-	// "golang.org/x/crypto/curve25519"
-	// "https://pkg.go.dev/crypto/ed25519#PrivateKey
-	// "crypto/ed25519"ccc1be8d-24dc-41ad-9d66-b657711419d7
 	"reflect"
-	// "filippo.io/edwards25519"
 )
 
 func readEntity(keypath string) (*openpgp.Entity, error) {
@@ -49,136 +38,79 @@ var (
 	UnsupportedKeyType = errors.New("only ed25519 keys are supported")
 )
 
-func ed25519PrivateKeyToCurve25519(pk ed25519.PrivateKey) ([]byte, error) {
-	h := sha512.New()
-	_, err := h.Write(pk.Seed())
-	if err != nil {
-		return []byte{}, err
-	}
-	out := h.Sum(nil)
-	return out[:curve25519.ScalarSize], nil
-}
-
-func SSHPrivateKeyToAge(bytes []byte) (*string, error) {
-	s, err := bech32.Encode("AGE-SECRET-KEY-", bytes)
-	if err != nil {
-		return nil, err
-	}
-	s = strings.ToUpper(s)
-	return &s, nil
-}
-
 func main() {
-  // TODO turn these into CLI inputs
+	var keyfile string
-	// keyfile := "/home/pinpox/gnutmp/0xA5BCEFD22D30118A.priv.asc"
+	log.Println("Enter path to private PGP key (default: ./priv.asc):")
-	keyfile := "./test-key.asc"
+	_, err := fmt.Scanf("%s", &keyfile)
+	if err != nil && err.Error() == "unexpected newline" {
+		keyfile := "./priv.asc"
+	} else if err != nil {
+		log.Fatal(err)
+	}
 
 	e, err := readEntity(keyfile)
 	if err != nil {
 		log.Fatal(err)
 	}
 
-	spew.Config.MaxDepth = 2
+	log.Println("Keys:")
-	spew.Config.Indent = "     "
+	log.Println("[0]", e.PrimaryKey.KeyIdString()+" (primary)")
+	for i := 0; i < len(e.Subkeys); i++ {
+		log.Println(fmt.Sprintf("[%d]", i+1), e.Subkeys[i].PublicKey.KeyIdString()+" (subkey)")
+	}
 
-  log.Println("Keys:")
+	log.Println("Choose key by index (default: 0):")
-  log.Println("[0]", e.PrimaryKey.KeyIdString() + " (primary)")
-  for i := 0; i < len(e.Subkeys); i++ {
-    log.Println(fmt.Sprintf("[%d]", i + 1), e.Subkeys[i].PublicKey.KeyIdString() + " (subkey)")
-  }
 
-  log.Println("Please choose a key by index (default: 0):")
+	var keyIndex int
+	_, err = fmt.Scanf("%d", &keyIndex)
+	if err != nil && err.Error() == "unexpected newline" {
+		keyIndex = 0
+	} else if err != nil {
+		log.Fatal(err)
+	}
 
-  var keyIndex int
+	var targetKey *packet.PrivateKey
-  _, err = fmt.Scanf("%d", &keyIndex)
+	if keyIndex == 0 {
-  if err != nil && err.Error() == "unexpected newline" {
+		log.Println(fmt.Sprintf("Continuing with key [%d]", keyIndex), e.PrimaryKey.KeyIdString())
-    keyIndex = 0
+		targetKey = e.PrivateKey
-  } else if err != nil {
+	} else if keyIndex > 0 {
-    log.Fatal(err)
+		var subkey = e.Subkeys[keyIndex-1]
-  }
+		log.Println(fmt.Sprintf("Continuing with key [%d]", keyIndex), subkey.PublicKey.KeyIdString())
+		targetKey = subkey.PrivateKey
+	} else {
+		log.Fatal("Invalid key index")
+	}
 
-  var targetKey *packet.PrivateKey
+	if targetKey.Encrypted {
-  if keyIndex == 0 {
+		log.Println("Please enter passphrase to decrypt PGP key:")
-    log.Println(fmt.Sprintf("Continuing with key [%d]", keyIndex), e.PrimaryKey.KeyIdString())
+		bytePassphrase, err := term.ReadPassword(int(syscall.Stdin))
-    targetKey = e.PrivateKey
+		if err != nil {
-  } else if keyIndex > 0 {
+			log.Fatal(err)
-    var subkey = e.Subkeys[keyIndex - 1]
+		}
-    log.Println(fmt.Sprintf("Continuing with key [%d]", keyIndex), subkey.PublicKey.KeyIdString())
+		targetKey.Decrypt(bytePassphrase)
-    targetKey = subkey.PrivateKey
+	}
-  } else {
-    log.Fatal("Invalid key index")
-  }
 
-  if targetKey.Encrypted {
+	log.Println("private key type:", reflect.TypeOf(targetKey.PrivateKey))
-    log.Println("Please enter passphrase to decrypt PGP key:")
+	castkey, ok := targetKey.PrivateKey.(*eddsa.PrivateKey)
-    bytePassphrase, err := term.ReadPassword(int(syscall.Stdin))
+	if !ok {
-    if err != nil {
+		log.Fatal("failed to cast")
-      log.Fatal(err)
+	}
-    }
-    targetKey.Decrypt(bytePassphrase)
-  }
 
-  log.Println("private key type:", reflect.TypeOf(targetKey.PrivateKey))
+	log.Println("public key type:", reflect.TypeOf(castkey.PublicKey))
-  castkey, ok := targetKey.PrivateKey.(*eddsa.PrivateKey)
-  if !ok {
-    log.Fatal("failed to cast")
-  }
-	// spew.Dump(castkey)
-
-  // get public key as OpenSSH key
-  log.Println("public key type:", reflect.TypeOf(castkey.PublicKey))
 	var pubkey ed25519.PublicKey = castkey.PublicKey.X
 
-	agePub, err := bech32.Encode("age", pubkey)
+	sshPub, err := ssh.NewPublicKey(pubkey)
-  if err != nil {
-    log.Fatal(err)
-  }
-  log.Println("public age key:", string(agePub))
-
-  sshPub, err := ssh.NewPublicKey(pubkey)
-  if err != nil {
-    log.Fatal(err)
-  }
-  // log.Println("public key SSH key wire format:", sshPub.Marshal())
-  // log.Println("public key SHA256:", ssh.FingerprintSHA256(sshPub))
-  log.Println("public SSH key:", string(ssh.MarshalAuthorizedKey(sshPub)))
-
-	// TODO: are these the correct bytes?
-	// var privkey ed25519.PrivateKey = castkey.D
-	// var privkey ed25519.PrivateKey = castkey.MarshalByteSecret()
-  var privkey = ed25519.NewKeyFromSeed(castkey.D)
-
-  // TODO is this right?
-	bytes, err := ed25519PrivateKeyToCurve25519(privkey)
 	if err != nil {
 		log.Fatal(err)
 	}
+	log.Println("public SSH key:\n" + string(ssh.MarshalAuthorizedKey(sshPub)))
 
-	// bytes = privkee
+	var privkey = ed25519.NewKeyFromSeed(castkey.D)
 
-  // TODO trying to get private key as age key
+	privPem, err := ssh.MarshalPrivateKey(&privkey, "")
-	agekey, err := SSHPrivateKeyToAge(bytes)
 	if err != nil {
 		log.Fatal(err)
 	}
-	fmt.Println(*agekey)
+	privateKeyPem := pem.EncodeToMemory(privPem)
-
+	log.Println("Private SSH key:\n" + string(privateKeyPem))
-  // TODO trying to get private key as OpenSSH key
-  privPem, err := ssh.MarshalPrivateKey(privkey, "")
-  if err != nil {
-    log.Fatal(err)
-  }
-  if err := pem.Encode(os.Stdout, privPem); err != nil {
-		log.Fatal(err)
-	}
-
-  // TODO make sure public key is still the same
-  var priv ed25519.PrivateKey = bytes
-  var pubkey2 = priv.Public()
-  // var pubkey2 = privkey.Public()
-  sshPub2, err := ssh.NewPublicKey(pubkey2)
-  if err != nil {
-    log.Fatal(err)
-  }
-  log.Println("verify public SSH key:", string(ssh.MarshalAuthorizedKey(sshPub2)))
 }