I get this error when trying to decrypt a certain encrypted MIME message:
AlgorithmIdentifier: oid: 1.2.840.113518.104.22.168 Unsupported public key algorithm
The OID 1.2.840.113522.214.171.124 is for "RSA OAEP" instead of the much more common "RSA PKCS1 v1.5". Chilkat already implements RSA OAEP. The problem within the component is that it did not recognize the OID. This is fixed and can be made available in a pre-release. Versions after v9.3.1 will include this fix.