How to pass the private key as a String in Java in order to connect via SFTP using SSHJ?

The following code works to connect via SFTP, the directory path of the key is used in order to load it.

Here's the current code (I've specified the libraries just in case)

import net.schmizz.sshj.SSHClient;
import net.schmizz.sshj.userauth.keyprovider.KeyProvider;
import net.schmizz.sshj.transport.verification.PromiscuousVerifier;

SSHClient sftp = new SSHClient();
KeyProvider privateKey = sftp.loadKeys("/home/sample/.ssh/id_rsa");
sftp.addHostKeyVerifier(new PromiscuousVerifier());
sftp.connect("111.222.333.444");
sftp.authPublickey("sample", privateKey);

Is there a way to pass the Private Key's content as a String instead of using its directory path?

Solution

Yes, you can invoke the method net.schmizz.sshj.SSHClient.loadKeys(String, String, PasswordFinder) of the library to support the use-case.

/**
 * Creates a {@link KeyProvider} instance from passed strings. Currently only PKCS8 format private key files are
 * supported (OpenSSH uses this format).
 * <p/>
 *
 * @param privateKey     the private key as a string
 * @param publicKey      the public key as a string if it's not included with the private key
 * @param passwordFinder the {@link PasswordFinder} that can supply the passphrase for decryption (may be {@code
 *                       null} in case keyfile is not encrypted)
 *
 * @return the key provider ready for use in authentication
 *
 * @throws SSHException if there was no suitable key provider available for the file format; typically because
 *                      BouncyCastle is not in the classpath
 * @throws IOException  if the key file format is not known, etc.
 */   
public KeyProvider loadKeys(String privateKey, String publicKey, PasswordFinder passwordFinder) throws IOException

If that is not available in the version of library you're using then considered upgrading it.

<dependency>
    <groupId>net.schmizz</groupId>
    <artifactId>sshj</artifactId>
    <version>0.10.0</version>
</dependency>