- Add a README.md to sshauthentication-api

- Add a note regarding the use of the hash algorithm parameter for EdDSA
  signatures

sshauthentication-api/README.md

@@ -0,0 +1,11 @@
+# SSH authentication API library
+
+The SSH authentication API library provides an interface to using an external authentication provider in the SSH authentication layer.
+
+### License
+[Apache License v2](https://github.com/open-keychain/openpgp-api/blob/master/LICENSE)
+
+### API
+For a basic rundown of the API design see the OpenPGP API library's [README.md](https://github.com/open-keychain/openpgp-api/blob/master/README.md).
+For a description of the supported methods see [``org.openintents.ssh.authentication.SshAuthenticationApi``](https://github.com/open-keychain/open-keychain/blob/master/sshauthentication-api/src/main/java/org/openintents/ssh/authentication/SshAuthenticationApi.java)
+

sshauthentication-api/src/main/java/org/openintents/ssh/authentication/SshAuthenticationApi.java

@@ -49,6 +49,8 @@ public class SshAuthenticationApi {
      *
      * returned extras:
      * byte[]        EXTRA_SIGNATURE
+     *
+     * Note: for EdDSA the hash algorithm is ignored, PureEdDSA has to be implemented
      */
     public static final String ACTION_SIGN = "org.openintents.ssh.action.SIGN";
     public static final String EXTRA_CHALLENGE = "challenge";