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Merge pull request #44 from keybase/david/revert-ed25519-everywhere
Revert ed25519 everywhere
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,47 +1,83 @@ | ||
| package sshutils | ||
|
|
||
| import ( | ||
| "crypto/ecdsa" | ||
| "crypto/elliptic" | ||
| "crypto/rand" | ||
| "crypto/x509" | ||
| "encoding/pem" | ||
| "fmt" | ||
| "io/ioutil" | ||
| "os" | ||
| "os/exec" | ||
| "strings" | ||
|
|
||
| "github.com/ScaleFT/sshkeys" | ||
| "github.com/keybase/bot-sshca/src/shared" | ||
| "golang.org/x/crypto/ed25519" | ||
| "golang.org/x/crypto/ssh" | ||
|
|
||
| "github.com/keybase/bot-sshca/src/shared" | ||
| ) | ||
|
|
||
| // Generate a new SSH key. Places the private key at filename and the public key at filename.pub. | ||
| // We use ed25519 keys since they may be more secure (and are smaller). The go crypto ssh library | ||
| // does not support marshalling ed25519 keys so we use ScaleFT/sshkeys to marshal them to the | ||
| // correct on disk format for SSH | ||
| // Generate a new SSH key and store the private key at filename and the public key at filename.pub | ||
| // If the ssh-keygen binary exists, generates an ed25519 ssh key using ssh-keygen. Otherwise, | ||
| // generates an ecdsa key using go's crypto library. Note that we use ecdsa rather than ed25519 | ||
| // in this case since go's crypto library does not support marshalling ed25519 keys into the format | ||
| // expected by openssh. github.com/ScaleFT/sshkeys claims to support this but does not reliably | ||
| // work with all versions of ssh. | ||
| func generateNewSSHKey(filename string) error { | ||
| // Generate the key | ||
| pub, private, err := ed25519.GenerateKey(rand.Reader) | ||
| if sshKeygenBinaryExists() { | ||
| return generateNewSSHKeyEd25519(filename) | ||
| } | ||
|
|
||
| return generateNewSSHKeyEcdsa(filename) | ||
| } | ||
|
|
||
| // Returns true iff the ssh-keygen binary exists and is in the user's path | ||
| func sshKeygenBinaryExists() bool { | ||
| _, err := exec.LookPath("ssh-keygen") | ||
| return err == nil | ||
| } | ||
|
|
||
| // Generate an ed25519 ssh key via ssh-keygen. Stores the private key at filename and the public key at filename.pub | ||
| func generateNewSSHKeyEd25519(filename string) error { | ||
| cmd := exec.Command("ssh-keygen", "-t", "ed25519", "-f", filename, "-m", "PEM", "-N", "") | ||
| bytes, err := cmd.CombinedOutput() | ||
| if err != nil { | ||
| return fmt.Errorf("failed to generate ed25519 key: %v", err) | ||
| return fmt.Errorf("ssh-keygen failed: %s (%v)", strings.TrimSpace(string(bytes)), err) | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // Write the private key | ||
| bytes, err := sshkeys.Marshal(private, &sshkeys.MarshalOptions{Format: sshkeys.FormatOpenSSHv1}) | ||
| // Generate an ecdsa ssh key in pure go code. Stores the private key at filename and the public key at filename.pub | ||
| // Note that if you are editing this code, be careful to ensure you test it manually since the integration tests | ||
| // run in an environment with ssh-keygen and thus do not call this function. This function is manually used on windows. | ||
| func generateNewSSHKeyEcdsa(filename string) error { | ||
| // ssh-keygen -t ecdsa uses P256 by default | ||
| privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to marshal ed25519 key: %v", err) | ||
| return err | ||
| } | ||
| err = ioutil.WriteFile(filename, bytes, 0600) | ||
|
|
||
| // 0600 are the correct permissions for an ssh private key | ||
| privateKeyFile, err := os.OpenFile(filename, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to write ssh private key to %s: %v", filename, err) | ||
| return err | ||
| } | ||
| defer privateKeyFile.Close() | ||
|
|
||
| // Write the public key | ||
| publicKey, err := ssh.NewPublicKey(pub) | ||
| bytes, err := x509.MarshalECPrivateKey(privateKey) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to create public key from ed25519 key: %v", err) | ||
| return err | ||
| } | ||
| bytes = ssh.MarshalAuthorizedKey(publicKey) | ||
| err = ioutil.WriteFile(shared.KeyPathToPubKey(filename), bytes, 0600) | ||
|
|
||
| privateKeyPEM := &pem.Block{Type: "EC PRIVATE KEY", Bytes: bytes} | ||
| err = pem.Encode(privateKeyFile, privateKeyPEM) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to write ssh public key to %s: %v", shared.KeyPathToPubKey(filename), err) | ||
| return err | ||
| } | ||
|
|
||
| return nil | ||
| pub, err := ssh.NewPublicKey(&privateKey.PublicKey) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| return ioutil.WriteFile(shared.KeyPathToPubKey(filename), ssh.MarshalAuthorizedKey(pub), 0600) | ||
| } |
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