"The RSA-KEM Key Transport Algorithm is a one-pass (store-and-forward) mechanism for transporting keying data to a recipient using the recipient's RSA public key. (""KEM"" stands for ""key encapsulation mechanism"".) This document specifies the conventions for using the RSA-KEM Key Transport Algorithm with the Cryptographic Message Syntax (CMS). The ASN.1 syntax is aligned with an expected forthcoming change to American National Standard (ANS) X9.44."
RFC 5990-2010 history
2010RFC 5990-2010 Use of the RSA-KEM Key Transport Algorithm in the Cryptographic Message Syntax (CMS)