use RSA-KEM in CMS

RFC 9690 Use of the RSA-KEM Algorithm in the Cryptographic Message Syntax (CMS)

ISO/IEC 18033-2 Information technology — Security techniques — Encryption algorithms Part 2: Asymmetric ciphers

直接用ISO/IEC 18033-2的RSA-KEM加密随机数z，通过KDF派生KEK。KEK保护CEK。CEK保护Private Key。

\[ct = z^e mod n SS = KDF(z, ssLen) KEK = KDF(SS, kekLength, otherInfo) WK = WRAP(KEK, CEK)\]