<PackageReference Include="BouncyCastle.Cryptography" Version="2.4.0" />

Org.BouncyCastle.Asn1.X509.AltSignatureAlgorithm

public static AltSignatureAlgorithm GetInstance(object obj)

public static AltSignatureAlgorithm GetInstance(Asn1TaggedObject taggedObject, bool declaredExplicit)