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package ssh
import (
"io/ioutil"
"strconv"
"github.com/pkg/errors"
"github.com/smallstep/certificates/api"
"github.com/smallstep/certificates/authority/provisioner"
"github.com/smallstep/certificates/ca/identity"
"github.com/smallstep/cli/command"
"github.com/smallstep/cli/crypto/keys"
"github.com/smallstep/cli/crypto/pemutil"
"github.com/smallstep/cli/errs"
"github.com/smallstep/cli/flags"
"github.com/smallstep/cli/ui"
"github.com/smallstep/cli/utils"
"github.com/smallstep/cli/utils/cautils"
"github.com/urfave/cli"
"golang.org/x/crypto/ssh"
)
func rekeyCommand() cli.Command {
return cli.Command{
Name: "rekey",
Action: command.ActionFunc(rekeyAction),
Usage: "rekey a SSH certificate using the SSH CA",
UsageText: `**step ssh rekey** <ssh-cert> <ssh-key>
[**--out**=<file>] [**--issuer**=<name>] [**--password-file**=<path>]
[**--force**] [**--ca-url**=<uri>] [**--root**=<path>]
[**--offline**] [**--ca-config**=<path>]`,
Description: `**step ssh rekey** command generates a new SSH Certificate and key using
an existing SSH Cerfificate and key pair to authenticate and templatize the
request. It writes the new certificate to disk - either overwriting
<ssh-cert> or using new files when the **--out**=<file> flag is used.
## POSITIONAL ARGUMENTS
<ssh-cert>
: The ssh certificate to renew.
<ssh-key>
: The ssh certificate private key.
## EXAMPLES
Rekey an ssh certificate:
'''
$ step ssh rekey id_ecdsa-cert.pub id_ecdsa
'''
Rekey an ssh certificate creating id2_ecdsa, id2_ecdsa.pub, and id2_ecdsa-cert.pub:
'''
$ step ssh rekey --out id2_ecdsa id_ecdsa-cert.pub id_ecdsa
'''`,
Flags: []cli.Flag{
cli.StringFlag{
Name: "out",
Usage: `The new key <file> path. Defaults to overwriting the <ssh-cert> positional argument.`,
},
flags.Provisioner,
sshProvisionerPasswordFlag,
flags.NoPassword,
flags.Insecure,
flags.Force,
flags.CaURL,
flags.Root,
flags.Offline,
flags.CaConfig,
flags.SSHPOPCert,
flags.SSHPOPKey,
},
}
}
func rekeyAction(ctx *cli.Context) error {
if err := errs.NumberOfArguments(ctx, 2); err != nil {
return err
}
args := ctx.Args()
certFile := args.Get(0)
keyFile := args.Get(1)
// SSH uses fixed suffixes for public keys and certificates
var newPubFile, newCertFile, newKeyFile string
if out := ctx.String("out"); out != "" {
newPubFile = out + ".pub"
newCertFile = out + "-cert.pub"
newKeyFile = out
} else {
newPubFile = keyFile + ".pub"
newCertFile = certFile
newKeyFile = keyFile
}
// Extra flags
passwordFile := ctx.String("password-file")
noPassword := ctx.Bool("no-password")
insecure := ctx.Bool("insecure")
flow, err := cautils.NewCertificateFlow(ctx)
if err != nil {
return err
}
// Load the cert, because we need the serial number.
certBytes, err := ioutil.ReadFile(certFile)
if err != nil {
return errors.Wrapf(err, "error reading ssh certificate from %s", certFile)
}
sshpub, _, _, _, err := ssh.ParseAuthorizedKey(certBytes)
if err != nil {
return errors.Wrapf(err, "error parsing ssh public key from %s", certFile)
}
cert, ok := sshpub.(*ssh.Certificate)
if !ok {
return errors.New("error casting ssh public key to ssh certificate")
}
serial := strconv.FormatUint(cert.Serial, 10)
ctx.Set("sshpop-cert", certFile)
ctx.Set("sshpop-key", keyFile)
token, err := flow.GenerateSSHToken(ctx, serial, cautils.SSHRekeyType, nil, provisioner.TimeDuration{}, provisioner.TimeDuration{})
if err != nil {
return err
}
caClient, err := flow.GetClient(ctx, token)
if err != nil {
return err
}
// Generate keypair
pub, priv, err := keys.GenerateDefaultKeyPair()
if err != nil {
return err
}
sshPub, err := ssh.NewPublicKey(pub)
if err != nil {
return errors.Wrap(err, "error creating public key")
}
resp, err := caClient.SSHRekey(&api.SSHRekeyRequest{
OTT: token,
PublicKey: sshPub.Marshal(),
})
if err != nil {
return err
}
// Private key (with password unless --no-password --insecure)
opts := []pemutil.Options{
pemutil.WithOpenSSH(true),
pemutil.ToFile(newKeyFile, 0600),
}
switch {
case noPassword && insecure:
case passwordFile != "":
opts = append(opts, pemutil.WithPasswordFile(passwordFile))
default:
opts = append(opts, pemutil.WithPasswordPrompt("Please enter the password to encrypt the private key"))
}
_, err = pemutil.Serialize(priv, opts...)
if err != nil {
return err
}
// Write public key
if err := utils.WriteFile(newPubFile, marshalPublicKey(sshPub, cert.KeyId), 0644); err != nil {
return err
}
// Write certificate
if err := utils.WriteFile(newCertFile, marshalPublicKey(resp.Certificate, cert.KeyId), 0644); err != nil {
return err
}
// Write renewed identity
if len(resp.IdentityCertificate) > 0 {
if err := identity.WriteIdentityCertificate(resp.IdentityCertificate); err != nil {
return err
}
}
ui.PrintSelected("Private Key", newKeyFile)
ui.PrintSelected("Public Key", newPubFile)
ui.PrintSelected("Certificate", newCertFile)
return nil
}
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