15.4. The asymmetric cryptographic system shall provide for the issue of a signing key pair by means of which the transmitted documents are signed and their source identified.
The system shall also provide for the issue of an encryption key pair to protect the confidentiality of the documents being transmitted. Confidentiality is ensured by encrypting the data by means of a randomly variable secret key generated by the symmetric cryptographic system. That key is itself encrypted with the public key that forms part of the encryption key pair of the intended recipient, namely, the registry office, which decrypts the transmitted data with its private key.
The system shall also include a hash function by means of which the registry office can verify the integrity and completeness of the documents it receives.