This part of ISO/IEC 18033 specifies several asymmetric ciphers. These specifications prescribe the functional interfaces and correct methods of use of such ciphers in general, as well as the precise functionality and cipher text format for several specific asymmetric ciphers (although conforming systems may choose to use alternative formats for storing and transmitting cipher-texts). A normative annex (Annex A) gives ASN.1 syntax for object identifiers, public keys, and parameter structures to be associated with the algorithms specified in this part of ISO/IEC 18033. However, these specifications do not prescribe protocols for reliably obtaining a public key, for proof of possession of a private key, or for validation of either public or private keys; see ISO/IEC 11770-3 for guidance on such key management issues. The asymmetric ciphers that are specified in this part of ISO/IEC 18033 are indicated in Clause 7.6. NOTE Briefly, the asymmetric ciphers are: ? ECIES-HC; PSEC-HC; ACE-HC: generic hybrid ciphers based on ElGamal encryption; ? RSA-HC: a generic hybrid cipher based on the RSA transform; ? RSAES: the OAEP padding scheme applied to the RSA transform; ? HIME(R): a scheme based on the hardness of factoring.