[SSHD-984] Utility method to export KeyPair in OpenSSH format

• Type: New Feature
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.4.0
• Fix Version/s: 2.5.0
• Assignee: Unassigned
• Reporter: David Ostrovsky
• Created: 28/Apr/20 10:04
• Updated: 07/May/20 15:49
• Resolved: 04/May/20 15:32

Description

There are ongoing efforts in Gerrit Code Review and JGit projects to remove dependency on JSch library: [1], [2]. Instead, MINA SSSD should be used on both: client and server sides.

One difficulty we are facing is the fact the MINA SSHD currently doesn't provide any means to export generated KeyPair in OpenSSH format.

Thomas Wolf added recently the ability to read encrypted OpenSSH private keys in context of SSHD-708.

With JSch this code would do the job:

  public static com.jcraft.jsch.KeyPair genSshKey() throws JSchException {
    JSch jsch = new JSch();
    return KeyPair.genKeyPair(jsch, KeyPair.ECDSA, 256);
  }

  public static String publicKey(com.jcraft.jsch.KeyPair sshKey, @Nullable String comment)
      throws UnsupportedEncodingException {
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    sshKey.writePublicKey(out, comment);
    return out.toString(US_ASCII.name()).trim();
  }

  public static byte[] privateKey(com.jcraft.jsch.KeyPair keyPair) {
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    keyPair.writePrivateKey(out);
    return out.toByteArray();
  }

[1] https://bugs.eclipse.org/bugs/show_bug.cgi?id=540727
[2] https://bugs.chromium.org/p/gerrit/issues/detail?id=12599

Issue Links

• incorporates: SSHD-707 Add support for writing OpenSSH ed25519 private keys to file
• relates to: SSHD-708 Add support for password encrypted OpenSSH private key files