Android SSHJ exception upon connect() - "KeyFactory ECDSA implementation not found"

Android ships with a cut down version of BouncyCastle which does not include the ECDSA algorithms. So even though you include the full version in your class path, the Android runtime version will be picked up and used.

You may want to look at http://rtyley.github.io/spongycastle/ which was created to get around this, its a repackaged version of Bouncycastle that can be installed as a separate JCE provider in Android. Just install it as the default JCE provider before you try to connect with SSHJ (untested).

Security.insertProviderAt(new org.spongycastle.jce.provider.BouncyCastleProvider(), 1);

First add this BouncyCastle library in app/build.gradle file:

implementation 'org.bouncycastle:bcpkix-jdk15on:1.64'

Then in your activity file, add a static block to remove the default BouncyCastle provider found in Android with our version:

    static {
        Security.removeProvider("BC");//first remove default os provider
        Security.insertProviderAt(new BouncyCastleProvider(), 1);//add new provider
    }

This will resolve the algorithm implementation not found issue.

Downgrade to sshj 0.9.0 here: http://mvnrepository.com/artifact/net.schmizz/sshj/0.9.0

The problem seems to have been introduced in 0.10.x. Also, I have tried the other JCE provider but got into the same trouble.