Showing papers on "Cipher published in 1978"

Exponentiation cryptographic apparatus and method

Abstract: A cryptographic system transmits a computationally secure cryptogram that is generated from a secret transformation of the message sent by the authorized transmitter; the cryptogram is again transformed by the authorized receiver using a secret reciprocal transformation to reproduce the message sent. The secret transformations use secret cipher keys that are known only by the authorized transmitter and receiver. The transformations are performed with nonsecret operations, exponentiation, that are easily performed but extremely difficult to invert. It is computationally infeasible for an eavesdropper either to solve known plaintext-ciphertext pairs for the secret cipher keys, or to invert the nonsecret operations that are used to generate the cryptogram.

Personal identification system

Abstract: A method and apparatus for verifying that the bearer of a card (e.g., credit card, bank card, etc.) is authorized to use the card. The card bears machine-readable indicia of an account number (PAN) and the bearer of the card has memorized a personal identification number (PIN). There is associated with the PAN a check number (PCN) which is derived by (1) generating a first cipher Y1 by encrypting the PAN using the PIN in combination with a secret security number as a key, the bits of which address a data encryption process; (2) generating a second cipher by decrypting the first cipher using the secret security number as a key so that the decryption process is the reverse of the encryption process; and (3) storing the second cipher as the check number PCN in a machine-accessible location, which may be in a separate memory or recorded on the card itself. Verification is accomplished by (a) sensing the PAN from the machine-readable indicia on the card; (b) enciphering the PAN with respect to the data encryption process under control of a key which is a combination (such as by addition) of the PIN and the secret security number to thereby produce a third cipher; (c) sensing the PCN from the machine-accessible location; (d) enciphering the PCN with respect to the data encryption process under control of a key which is the secret security number to thereby produce a fourth cipher; and (e) accepting the card as valid provided the third and fourth ciphers bear a predetermined relationship to each other, such as equality.

Past dependent microcomputer cipher apparatus

Abstract: Apparatus for use in a secure data communication system includes a microcomputer that controls a cipher process by which sensitive data is encrypted before transmission. When activated, the apparatus accepts either cleartext or ciphertext and transforms the text to its opposite form according to an algorithm that is past dependent and which is also dependent on a pseudo random cipher key. Ciphertext may then be stored in an information retrieval system or transmitted to a destination terminal where the text is deciphered in real time by a corresponding second apparatus that stores the same key. In either case, security of transmitted and stored data is maintained since the sensitive data is in encrypted form. A set of logical instructions according to the algorithm is stored in a read only memory of the microcomputer which includes an EPROM unit having a data field of predetermined characters. The cipher process is initiated by a control character and starts with predetermined seeds that establish a first origin in the data field for each line of text to be encrypted. This origin is then translated to a second origin of the data field in response to four characters that are randomly generated by a counter. A variable sequence of iterative logical operations transforms cleartext to ciphertext and provides a key stream that is non-linear, random-like and which possesses an encryption period that is substantially longer than the period of any line so that the periodicity of the key stream is never indicated. The cipher keys for each line of text are temporarily stored in a read/write memory to permit editing operations and are erased at the onset of the next line.

THE HAGELIN CIPHER MACHINE (M-209) Reconstruction of the Internal Settings

Abstract: It is an Interesting and useful cryptanalytic problem to try to reconstruct the internal settings of the M-209 cipher machine, given the text of a message which has been obtained both in clear and enciphered form. Then it is considerably easier to decipher any further messages encrypted with the same internal settings. It turns out to be possible to do this reconstruction for rather short messages, of the order of 75 characters or so. Partial or incomplete solutions are generally possible with as few as 50 characters.

True person checking system

Abstract: PURPOSE:In an automatic depositing and paying, etc., the storage capacity of ledger files is reduced and the false use of cards is prevented by comparing the cipher data of users and the cipher data made out by user information.

Control system of automatic depositing machine

Abstract: PURPOSE:To shorten the time required for depositing, simplify operating procedures and prohibit checking and booking processing by other persons by means of a manual cipher inputter by reading the cipher with a reader of an approving medium and depositing money without inputting the cipher

Data processing terminal

Abstract: The invention concerns a data processing terminal. In an embodiment of the invention a data processing terminal coupled via a communication line to a remote host system includes data security device 11 (Fig. 2) which incudes storage means 13 for storing a master cipher key, cryr-ographic apparatus 12 for performing cryptographic operations, and control means 14 for controlling the writing of a master cipher key into the storage means 13, controlling the transfer of the master cipher key to the cryptographic apparatus 12 and controlling the cryptographic apparatus to perform cryptographic operations. When a new master cipher key is written into the storage means 13, the old master cipher key is automatically overwritten with an arbitrary value, after which the new master key may be written into the storage means. The cryptographic apparatus 23 (Fig. 3) of the data security device 11 includes data storage means BR17 and CR22, a working key storage means 20, and cipher means 25 for performing a cipher function on data stored in the cryptographic apparatus storage means under control of a working cipher key stored in the storage means 20, the resulting ciphered data being stored in the cryptographic apparatus storage means. A load cipher key direct function can be performed whereby a working cipher key may be loaded directly into the working key storage means 20 for use as a working cipher key in performing a cipher function. A decipher key function also can be performed whereby the master cipher key from 13 (Fig. 2) is transferred to the working key storage means 20 as a working cipher key after which an operational key enciphered under the master cipher key (received from the remote host system) is transferred to the cryptographic apparatus storage means and the control means causes the enciphered operational key to be deciphered to obtain the operational key in clear form as a working cipher key for subsequent encipher decipher data functions by the cipher means 25.

Privacy communication system by facsimile

Abstract: PURPOSE:To achieve an accurate information transmission by securing an automatic and high-speed cipher communication for the character and pattern information.

Information transmission system

Abstract: PURPOSE:To realize a secret information transmission system which can hold a high secrecy by giving the serial binary addition to the two output of the cipher information reader and the transmission information reader for transmission with addition of the synchronous signal and then carrying out the decoding at the reception side. CONSTITUTION:The secret information is prepared to transmission information medium 3, and the contents of the information is read at transmission side information reader 4 to be the input of adder 6 after output in the serial binary number. While the cipher information is written into cipher information medium 1a, and this contents is read by cipher information reader 2a to be supplied to adder 6 after output in the serial binary number. Adder 6 gives the binary addition to the two output, and the synchronous signal sent from synchronous signal generator circuit 5 is added to the output to be transmitted through transmission side transmission processor 7. The transmitted information is read by reception side transmission processor 10 and then supplied to subtractor 11 in the form of the serial binary number. On the other hand, the contents prepared at docoding information medium 1b is read through decode information reader 2b and then supplied to subtractor 11 to be subtracted according to the synchronous signal sent from synchronous signal detection circuit 12. Thus the original secret information is written into reception information medium 14.