Using ECDSA private key causes OpenSSL::PKey::RSAError

[bojan-drljaca-lu]

Looks like only RSA private key type can be used since ECDSA private key is not supported and exception OpenSSL::PKey::RSAError is raised with error message Neither PUB key nor PRIV key: nested asn1 error. I'm trying to do SAML request signing and there is no option to change this and line of code that breaks in a gem is OpenSSL::PKey::RSA.new(formatted_private_key) in lib/onelogin/ruby-saml/settings.rb and method is get_sp_key. Is there a possibility to change this since OpenSSL library does support reading different key reference https://docs.ruby-lang.org/en/2.4.0/OpenSSL/PKey.html
The PKey module offers support for three popular public/private key algorithms:

• RSA (OpenSSL::PKey::RSA)
• DSA (OpenSSL::PKey::DSA)
• Elliptic Curve Cryptography (OpenSSL::PKey::EC)