초록 ▼

The encryption key based on a blocking set cryptosystem includes knowledge of the blocking set, and ciphers (usually independent) on the blocking set and its complement. In order to decipher, a legitimate receiver needs to know only the blocking set and the cipher used on it. Thus it is not necessar

The encryption key based on a blocking set cryptosystem includes knowledge of the blocking set, and ciphers (usually independent) on the blocking set and its complement. In order to decipher, a legitimate receiver needs to know only the blocking set and the cipher used on it. Thus it is not necessary for the sender to transmit to anyone the cipher on the complement of the blocking set. The fact that part of the encryption key need not be transmitted is the fundamental difference between the proposed cryptosystem and the so-called private key system, where both the sender and receiver know, but keep secret, the encryption and decryption keys. Particularly useful applications of this scheme are two situations where a central person, institution or computer send out confidential information to several parties, but where none of the parties has the authority to transmit information to the group. This might apply to the main branch of a company, or to a certification authority in a cryptographic protocol. It can also be used to establish an access hierarchy in a computer or security network.

대표청구항 ▼

[ I claim:] [1.] A method of transmitting information between authorized sites including a transmission site and a receiving site such that the information is secure from non-authorized sites comprising:providing to the authorized sites a set of messages which can be transmitted between the sites, e

[ I claim:] [1.] A method of transmitting information between authorized sites including a transmission site and a receiving site such that the information is secure from non-authorized sites comprising:providing to the authorized sites a set of messages which can be transmitted between the sites, each message being a string of bits in identifiable positions, and each message being allocated an agreed meaning;communicating to the authorized sites information identifying for the set of messages selected positions of the bits so that others of the positions of the bits are not selected, the selection of positions being arranged to allow determination of a unique message from the messages set by analysis of the bits in said selected positions;providing a secret encryption key and a corresponding secret decryption key such that the secret encryption key is known to said transmission site and the corresponding secret decryption key is known to said receiving site;providing to said transmission site a second encryption key different from said secret encryption key;selecting at the transmission site from the set of messages a subset of messages to be transmitted;at the transmission site encrypting for the subset of messages, using said secret encryption key, only the bits at the selected positions;at the transmission site encrypting for the subset of messages, using said second encryption key, the bits at the not selected positions;transmitting the encrypted subset of messages from the transmission site;at the receiving site for each message of the subset decrypting the message using the decryption key to decrypt the bits at said selected positions;at the receiving site for each message of the subset analyzing the decrypted bits at said positions to determine each message from the set of messages;and providing a signature of the transmitting site by comparing the encrypted bits at the not selected positions with the bits at the not selected positions from the set of messages.