Abstract: A communication control in a communication network system using a mobile computer, capable of realizing flexible address control and management for the mobile computer. When the mobile computer is located within a home network, a communication with the mobile computer is carried out by transferring data using a home address specific to the mobile computer which is a private address. When the mobile computer is located within an external own organization network, a communication with the mobile computer is carried out by routing data to the external own organization network using a care-of address indicating a current visited location of the mobile computer in the system which is a global address, and addressing the mobile computer within the external own organization network using the home address.

Abstract: A modular arithmetic apparatus has a plurality of base parameter sets in read only memories. A base selection unit in the modular arithmetic apparatus selects one of the base parameters sets according to an input modulus p. A plurality of operation units 30, in the modular arithmetic apparatus, perform an arithmetic operation according to the selected base parameter set in parallel and obtain an arithmetic result.

Abstract: This invention intends to provide a tone signal detection circuit that accurately detects a tone signal regardless of a reception electric field strength. To accomplish this object, the tone signal detection circuit according to the invention is comprised of a first filter that extracts a signal of a specific frequency from an input signal, a second filter that excludes the signal of the specific frequency from the input signal and extracts signals of frequencies near the specific frequency, a subtractor that subtracts an output of the second filter from an output of the first filter, and a judgment circuit to judge whether the tone signal is present or not in the input signal on the basis of an output from the subtractor.

Abstract: The present invention provides an echo canceller having a holding portion which holds at least a communication frame length's worth of reception signals; a power calculation portion which calculates power for each communication frame based on the reception signals held in this holding portion; a divider which divides, by the power calculated for each communication frame, the echo elimination residue signal for each sample of the communication frame output from a subtractor; and an update portion which updates the tap coefficients of an adaptive filter according to the output signals from the divider.

Abstract: A packet processing and packet transfer scheme capable of reducing the packet processing overhead by eliminating a need to decrypt and re-encrypt the entire packet at a time of relaying encrypted packets. In a packet processing device for relaying encrypted packets, a packet transferred to the packet processing device is received, where the packet has a packet processing key to be used in a prescribed packet processing with respect to a data portion of the packet, and the packet processing key is encrypted by using a first master key shared between a last device that applied a cipher communication related processing to the packet and the packet processing device.

Abstract: A packet authentication and packet encryption/decryption scheme for a security gateway suitable for a hierarchically organized network system and a mobile computing environment. For the packet authentication, in addition to the end-to-end authentication at the destination side packet processing device, the link-by-link authentication at each intermediate packet processing device in the packet transfer route is used. For the packet encryption/decryption, each packet processing device determines whether or not to encrypt/decrypt the packet according to: an information on the computers which are directly managed by this packet processing device; or the encryption information and the signature information provided in the packet; or the encryption information, the signature information, and the encryption/decryption level information provided in the packer.

Abstract: A transmission device performs encoding by a speech encoding portion including a speech encoder and error correction encoder, and transmits a continuous signal without any further processing. A reception device receives the continuous signal and performs channel decoding and speech decoding as one unit by a speech decoding portion including a soft-decision error correction decoder and a soft-decision speech decoder. Thus, a transmission and reception system performs an accurate signal reproduction without removing the signal including a normal bit error rate by correcting the error by the speech decoder.

Abstract: A mobile computer and a packet encryption and authentication method which are capable of controlling an activation of a packet encryption and authentication device belonging to the mobile computer according to the security policy at the visited network of the mobile computer. The mobile computer is provided with a packet encryption and authentication unit having an ON/OFF switchable function for applying an encryption and authentication processing on input/output packets of the mobile computer.

Abstract: A mobile computing scheme capable of carrying out a proper packet transfer according to a current location of the mobile computer by accounting for the network operating policy. A mobile computer carries out a prescribed communication processing according to recognition results as to whether the mobile computer is located inside or outside the home network at which a mobile computer management device of the mobile computer is provided, and whether or not there exists a packet processing device which has a packet transmitted by at least one of the mobile computer and a correspondent computer as an encryption and authentication processing target.

Abstract: A packet transfer scheme for realizing a control of a packet inspection device to pass only packets from those mobile computers that can be recognized as authenticated among non-management target mobile computers that had moved inside the network, to outside the network.

Abstract: A packet authentication and packet encryption/decryption scheme for a security gateway suitable for a hierarchically organized network system and a mobile computing environment. For the packet authentication, in addition to the end-to-end authentication at the destination side packet processing device, the link-by-link authentication at each intermediate packet processing device in the packet transfer route is used. The link-to-link authentication data being inspected by intermediate nodes and end-to-end data (different from link-to-link data) being inspected by destination node but not being inspected by intermediate nodes.

Abstract: A digital signature method comprises the signature data generating step of, by the use of system information including an elliptic curve E/Fq over a finite field and a base point G on the elliptic curve E/Fq, a signer's public key Y defined by a point on the elliptic curve E/Fq, and the signer's secret key x generated so as to fulfill the public key Y=x.multidot.

Abstract: A scheme for performing high speed Montgomery division within the Montgomery space. Montgomery division Y=B.multidot.A.sup.-1 .multidot.2.sup.n mod N for a positive integer N, a positive integer A which is relatively prime with respect to N and satisfying 0.ltoreq.A.ltoreq.N, a positive integer B, and an integer n which is satisfying n.gtoreq.L where L is a bit length of N in binary expression, is performed by obtaining a Montgomery inverse X=A.sup.-1 .multidot.2.sup.2n mod N from inputs A and N, and obtaining the Montgomery division Y=B.multidot.X.multidot.2.sup.-n mod N from the Montgomery inverse X and inputs B and N. Montgomery inverse X=A.sup.-1 .multidot.2.sup.2n mod N for a positive integer N, a positive integer A which is relatively prime with respect to N and satisfying 0.ltoreq.A<N, and an integer n which satisfies n.gtoreq.L where L is a bit length of N in binary expression, is determined by obtaining an intermediate result C=A.sup.-1 .multidot.2.sup.k mod N and a parameter k satisfying L.

Abstract: A user identification data management scheme for a networking computer systems formed by a plurality of computers which are mutually connected through a network. In this scheme, at each computer, whether an access request from a user at another computer to each computer is to be permitted or not is judged, and access permission data necessary in checking whether a communication to each computer is from one user at one computer from which an access to each computer by that one user is permitted is generated. The generated access permission data are then stored in a memory. Then, whether an access to each computer is directly made at each computer or indirectly made from another computer through the network is detected, whether that access is proper or not is judged in a case that access is indirectly made, and that access is permitted in a case that access is judged as proper, according to the access permission data stored in the memory.

Abstract: A file editing system that provides a high file content secrecy, a file version management, and an asynchronous editing is disclosed. For a high file content secrecy, the block data of files managed by a file management server device are enciphered in units of blocks, and a client device obtains the block data of the desired file in enciphered state, deciphers the obtained block data in units of blocks, carries out an editing of the desired file to obtain editing data, enciphers the editing data in units of blocks, and transmits the enciphered editing data to the file management server device.

Abstract: The most reliable server-aided computation system and method where a client request a server to perform modular exponentiation computation without revealing a cleint's secret to the server. The computation system includes a main device having a modular multiplication processing portion so that at least two integers are multiplied and a result thereof is divided by a modulus so as to obtain a residue thereof, exponent register portion for storing a secret exponent, and memory portion for storing a computed result in the processing portion; an auxiliary device having a modular multiplication processing portion for performing computation requested by the main device and sending back a result thus obtained therefrom to the main device; and communications channel for communicating data between the main device and the auxiliary device, wherein the auxiliary means performs computing steps without involving the secret exponent d which is only known to the main device.

Abstract: A cryptographic communication method comprises a step for carrying out cryptographic communication between a sending station and one or more receiving stations by using (1) a ciphertext formed by encrypting a unit of sending information under the intervention of at least a cryptographic key and (2) key-distribution-information produced by using at least the ciphertext, receiving station's public information, and randomized information generated in the sending station.

Abstract: A server-aided computation method using a main unit for processing secret information and at least one auxiliary unit for supporting a computation that said main unit executes, said method comprising the steps of generating d' from a secret key d' using m random numbers R.sub.i (where i=l, . . . , m) generated by said main unit having secret keys n and d, transferring d' and n from said main unit to said auxiliary unit, computing the following equation from a message block C in said auxiliary unitM'=C.sup.d' mod ncomputing X using said random numbers R.sub.i and n in said main unit while computing M' in said auxiliary unit, transferring M' from said auxiliary unit to said main unit, and computing a message block M using the following equation in said main unit.M=M'.multidot.