Secure encryption/decryption for elevators

This system relates to a secure encryption/decryption protocol for elevator displays and controls. The protocol uses an algorithm to scramble information before transmission and reassemble it after transmission. The system uses at least one block of data assembled into unencrypted N-bits of information. An encryption device encodes the data into at least one block of encrypted M-bits of information. A data encryption mask provides an encryption routine which also includes scrambling the data.

TECHNICAL FIELD

This invention relates to secure encryption/decryption protocol for elevator displays and controls. The protocol uses an algorithm to scramble information before transmission and reassemble it after transmission.

BACKGROUND OF THE INVENTION

Data encryption provides security for transmitted data by scrambling the “clear text” data into “scrambled text”. Typically, the transmitted data is scrambled in a manner selected by a unique key value. For example, this could be a 56-bit binary number. This then is unscrambled at the receiving station by a reverse process.

The present invention relates to a communication device for an elevator control system. The communication device performs data communication in a data communication network of the elevator control system.

More specifically, the communication protocol sends information to the elevators displays and controls. In the past, the format was extremely straightforward and easy to comprehend. Because of the straightforward manner in which the protocol was carried out, it was very insecure. A method and apparatus for generating secure elevator protocols was needed.

BRIEF SUMMARY OF THE INVENTION

The process and apparatus of this invention uses a secure communication in an elevator display and control systems. A primary controller provides information or controls the internal operations of at least one elevator. The system uses at least one block of data assembled into unencrypted N-bits of information, and an encryption device that encodes the data into at least one block of encrypted M-bits of information. A data encryption mask defines an encryption routine for placing the N-bits of information into M-bits of information using an algorithm. A transmitter transmits encrypted data from the primary controller of an elevator; and a decryption algorithm decodes the encrypted information into unencrypted information.

Within the old protocol, three basic packets were transmitted, a floor packet, a message packet, and a travel packet.

The floor packet could be broken down in to a floor header, a floor number, three ASCII characters describing the floor (i.e. LBY for Lobby), and some miscellaneous bits. The message packet would contain a message header, message number, three message characters, and some message bits. The travel packet would contain floor numbers, message numbers and single bits each representing a flag for a particular event like door strobes, chimes, up arrows, down arrows, and the like.

As mentioned above, these data packets were very insecure. It would be a simple matter for a person of skill to pick apart the data and discover how to use it. The ASCII information is especially easy to comprehend.

During the encryption, a data encryption mask is employed. The data encryption mask defines the encryption routine where all of the data bits should be placed. There are several data encryption masks. The decoding key bits make up a word that describes which mask was used during the encryption process.

In order to reassemble the information, an algorithm receives all three encrypted packets, determine which packet is which based upon the type nibble, resolves which encryption mask was employed when the data was scrambled, and then uses that same encryption mask to decipher the data and place it back into the floor, message and travel packets.

DETAILED DESCRIPTION OF THE INVENTION

In a preferred embodiment, the primary controller controls operations of a plurality of elevators and a plurality of subordinate controllers controls inputs to and outputs from the elevators. The system works well with a single elevator as well as multiple elevators.

FIG. 1is a block diagram for elevator control system10of this invention. System10includes controller12for controlling the internal operations of elevators14. Controller12manages elevator operations and communicates with MICRO COMM® Driver18. Driver18communicates through communication device16which is a network of common series transmission lines. Control12includes MICRO COMM® Driver18. System10transmits information pertaining to floor, door position, and direction through MICRO COMM® link18. MICRO COMM® is a registered trademark for elevator controls and floor indicators. Elevators14display information through elevator controls20which include displays which are visible in the cabs of the elevators. Hall displays22provide information in the lobbies and floors of buildings. Other displays24provide information where needed.

FIG. 2shows the components and operation of driver18and controls20which include MICRO COMM® receiver30. Driver18includes data source32providing bits of information to encryption algorithm34. Microprocessors36stores algorithm34. Microprocessor36using algorithm34transmits encrypted information through driver circuit38. Receiver30receives the encrypted information through receiver circuit40. Circuit40transmits the encrypted information to microprocessor42through decryption algorithm44. Algorithm44decodes the information and processor42sends the decrypted information to display46. While control20is described inFIG. 2, displays22and24include similar controls.

FIGS. 3-6are the flow charts for encryption and decryption according to this invention.FIGS. 3 and 4shows the steps needed for taking unencoded information, selecting an encryption mask, calling the encryption algorithm and transmitting encrypted data.FIGS. 5 and 6shows the steps for receiving transmitted encoded packets, calling the decryption algorithm, decoding the encrypted packets and using the decoded messages.

Prior to encoding any of the information, the data is assembled into 28 bits of floor information, 28 bits of message information, and 28 bits of travel information. These packets are very similar to the old packets where the floor packet would consist of a floor number, floor ASCII, and some miscellaneous bits. The other two packets are similar as well.

Then, the data is encoded into three 40-bit packets. These encoded packets are comprised of a start bit, type nibble (4-bits), decoding key bit, encrypted data, decoding key bit, checksum, and a stop bit. The type bits and the decoding key bits are not encrypted.

During the encryption, a data encryption mask is employed. The data encryption mask defines to the encryption routine where all of the data bits should be placed. There are several data encryption masks. The decoding key bits make up a word that describes which mask was used during the encryption process.

Bits from the structured 28-bit floor packet are scattered across all three of the encoded messages inside the encrypted portion of the data. The organized message and travel packets are scattered across the encoded messages in a similar fashion.

When the encryption is complete, three 40-bit packets house all of the floor, message and travel information. However all of the data has been scrambled based upon the encryption mask.

In order to reassemble the information, an algorithm will need receive all three encrypted packets, determine which packet is which based upon the type nibble, resolve which encryption mask was employed when the data was scrambled, and then use that same encryption mask to decipher the data and place it back into the floor, message and travel packets.

Prior to encoding and after decoding the Floor Packet looks like this:

Prior to encoding and after decoding the Message Packet looks like this:

Prior to encoding and after decoding the Travel Packet looks like this:

Three packets for transmission after Encryption:

In addition to these embodiments, persons skilled in the art can see that numerous modifications and changes may be made to the above invention without departing from the intended spirit and scope thereof.