sign_pss

        # OpenSSL::PKey::RSA.sign_pss

(from ruby core)
### Implementation from RSA
---
    rsa.sign_pss(digest, data, salt_length:, mgf1_hash:) -> String

---

Signs *data* using the Probabilistic Signature Scheme (RSA-PSS) and
returns the calculated signature.

RSAError will be raised if an error occurs.

See #verify_pss for the verification operation.

### Parameters
*digest*
:   A String containing the message digest algorithm name.
*data*
:   A String. The data to be signed.
*salt_length*
:   The length in octets of the salt. Two special values are reserved:
    `:digest` means the digest length, and `:max` means the maximum
    possible length for the combination of the private key and the
    selected message digest algorithm.
*mgf1_hash*
:   The hash algorithm used in MGF1 (the currently supported mask
    generation function (MGF)).


### Example
    data = "Sign me!"
    pkey = OpenSSL::PKey::RSA.new(2048)
    signature = pkey.sign_pss("SHA256", data, salt_length: :max, mgf1_hash: "SHA256")
    pub_key = OpenSSL::PKey.read(pkey.public_to_der)
    puts pub_key.verify_pss("SHA256", signature, data,
                            salt_length: :auto, mgf1_hash: "SHA256") # => true