[SSHD-1297] Load public key from file

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Information Provided
• Affects Version/s: 2.9.1

Environment

org.apache.sshd:sshd-sftp:2.9.1

+

openjdk version "17.0.3" 2022-04-19
OpenJDK Runtime Environment Temurin-17.0.3+7 (build 17.0.3+7)
OpenJDK 64-Bit Server VM Temurin-17.0.3+7 (build 17.0.3+7, mixed mode, sharing)

Language

Java

• Assignee: Unassigned
• Reporter: Daniel Hammer
• Created: 23/Sep/22 08:53
• Updated: 29/Oct/22 17:28
• Resolved: 29/Sep/22 17:18

Description

Hi SSHD gurus,

I'm attempting to utilize org.apache.sshd.common.util.buffer.ByteArrayBuffer to load a java.security.PublicKey, in-order to subsequently register the public key in a org.apache.sshd.server.auth.pubkey.PublickeyAuthenticator.

Ie. the idea is something like this

PublicKey myPublicKey;
try (InputStream is = new FileInputStream("/home/my-user/tmp/test_rsa_key.pub")) {
  ByteArrayBuffer buffer = new ByteArrayBuffer(org.apache.sshd.common.util.io.IoUtils.IoUtils.toByteArray(is));
  myPublicKey = buffer.getPublicKey(); // -> OutOfMemoryError: Java heap space ..?
//  myPublicKey = buffer.getRawPublicKey(); // -> Underflow ..?
}

ServerBuilder.builder()
    .publickeyAuthenticator(new KeySetPublickeyAuthenticator("my id", List.of(myPublicKey)))
    .build();

Resulting in the below exceptions, caused by internal guarding in ByteArrayBuffer before the ByteArrayBuffer.data would be processed.

getPublicKey():

java.lang.OutOfMemoryError: Java heap space
	at org.apache.sshd.common.util.buffer.ByteArrayBuffer.ensureCapacity(ByteArrayBuffer.java:277)
	at org.apache.sshd.common.util.buffer.Buffer.ensureCapacity(Buffer.java:1105)
	at org.apache.sshd.common.util.buffer.ByteArrayBuffer.wpos(ByteArrayBuffer.java:139)
	at org.apache.sshd.common.util.buffer.Buffer.getPublicKey(Buffer.java:521)
	at org.apache.sshd.common.util.buffer.Buffer.getPublicKey(Buffer.java:505)

getRawPublicKey():

org.apache.sshd.common.util.buffer.BufferException: Underflow: requested=1936943149, available=737
	at org.apache.sshd.common.util.buffer.Buffer.ensureAvailable(Buffer.java:640)
	at org.apache.sshd.common.util.buffer.ByteArrayBuffer.getString(ByteArrayBuffer.java:241)
	at org.apache.sshd.common.util.buffer.Buffer.getString(Buffer.java:309)
	at org.apache.sshd.common.util.buffer.Buffer.getRawPublicKey(Buffer.java:541)
	at org.apache.sshd.common.util.buffer.Buffer.getRawPublicKey(Buffer.java:530)

Seemingly my approach is incompatible with the available logic, unfortunately I've been unable to uncover documentation or Javadoc that could aid.

So as a last resort I'm turning to you gurus, in hopes of enlightenment (+ perhaps a PR guiding future developers in the desired direction via documentation / Javadoc).

Thanks in advance 🙏