class_docstr: Implementation for experiment payload builder
  using public key RSA encryption.
class_docstr_tok: ["Implementation","for","experiment","payload","builder","using","public","key","RSA","encryption","."]
code: def _get_fingerprint(self, signing_key):
      # This is hard-coded for now, until we figure out
      # a way to do this properly:
      encoding = self._add_encoding(
          b"ssh-ed25519"
      ) + self._add_encoding(signing_key)
  
      ssh_key_text: str = base64.b64encode(encoding).decode("utf-8")
      ssh_key = SSHKey("ssh-ed25519 {0}".format(ssh_key_text))
      try:
          ssh_key.parse()
      except Exception:
          self._raise_error("INVALID signing key type. ABORTING.")
  
      return ssh_key.hash_sha256()
  
imports: from Crypto.PublicKey import RSA
  from Crypto.Cipher import PKCS1_OAEP
  from Crypto.Hash import SHA256
  import nacl.secret
  import nacl.utils
  from nacl.signing import SigningKey, VerifyKey
  import base64
  import json
  from sshpubkeys import SSHKey
  from studio.ed25519_key_util import Ed25519KeyUtil
  from studio.payload_builders.payload_builder import PayloadBuilder
  from studio.util import logs
  from studio.payload_builders.unencrypted_payload_builder import UnencryptedPayloadBuilder
  from studio.util.util import check_for_kb_interrupt
label_desc: Use image node_id 4 for calling the EncryptedPayloadBuilder obj's underlying member method code with example usage: obj._get_fingerprint(signing_key) and returns: ssh_key