SshPrivateKeySigner.sign

SshSignResult sign(scope  const(ubyte)[]  requestData,
          string signatureAlgorithm)

Signs the request data with the loaded key.

`requestData`	Exact bytes to sign.
`signatureAlgorithm`	Requested signature algorithm; must match the key type (`ssh-ed25519`, `rsa-sha2-256` or `rsa-sha2-512` for RSA keys, or `ecdsa-sha2-nistp256`).

SshProgress.DONE with the signature, or

SshProgress.ERROR with SshError.SshErrorType.CAPABILITY when the requested algorithm does not fit the key or is rejected by policy.