Given a PKI infrastructure with a root node that signs CSR's for nodes Alice, Bob, and Carol. Is it possible for Alice to encrypt some information, store it publicly somewhere, then later Bob or Carol can decrypt that information, without Alice, Bob, nor Carol directly communicating?
The only thing they have in common is their PKI (each their private key, their public key and root's public key), and the one-way transfer of ciphertext from Alice to the public storage, then on to Bob or Carol.
Neither Bob nor Carol's public keys are available to Alice (in the real problem, Bob and Carol don't yet exist but will in the future, after Alice has generated the ciphertext)
The root CA cannot participate in this other than as a typical signer; that is, we cannot ask the root to do the encryption/decryption for us.