Abstract: A method for providing a warranty relating to a transaction between two parties, each party having a data communications device, in a system which includes an infrastructure composed of a plurality of locations each associated with a respective institution which provides services to clients, each location having a computer system, a database coupled to the computer system and storing information about each client of the institution and a data communications device coupled to the computer system for communication with the data communications device of any one party, each party being a client of at least one of the institutions, the method containing the steps of:

Abstract: A method is provided for an escrow cryptosystem that is essentially overhead-free, does not require a cryptographic tamper-proof hardware implementation (i.e., can be done in software), is publicly verifiable, and cannot be used subliminally to enable a shadow public key system. The keys generated are based on composite numbers (like RSA keys). A shadow public key system is an unescrowed public key system that is publicly displayed in a covert fashion. The keys generated by the method are auto-recoverable and auto-certifiable (abbrev. ARC). The ARC Cryptosystem is based on a key generation mechanism that outputs a public/private key pair, and a certificate of proof that the key is recoverable by the escrow authorities. Each generated public/private key pair can be verified efficiently to be escrowed properly by anyone. The verification procedure does not use the private key.

Abstract: A method for aiding transactions by providing warranties against various aspects of a transaction which may be hard to assure ahead of time or when high risk is involved in relying on them. The method employs an infrastructure of a computer and communication systems communication with various distributed organizations working together and providing warranties. Different parties may trust different organizations and user representatives of the infrastructure. A party in a transaction may ask for a warranty against another party. As a response, the infrastructure, through its organizations, calculates and provides a decision regarding the request. Relying on the warranty, the risk involved in conducting the electronic transaction is reduced. In the case where the transaction does not reach sound completion, the warranty can be claimed. The method also involves managing and administering the infrastructure, the entities in the transaction system and their outstanding warranties.

Abstract: A method is provided for an escrow cryptosystem that is essentially overhead-free, does not require a cryptographic tamper-proof hardware implementation (i.e., can be done in software), is publicly verifiable, and cannot be used subliminally to enable a shadow public key system. A shadow public key system is an unescrowed public key system that is publicly displayed in a covert fashion. The keys generated by the method are auto-recoverable and auto-certifiable (abbrev. ARC). The ARC Cryptosystem is based on a key generation mechanism that outputs a public/private key pair, and a certificate of proof that the key is recoverable by the escrow authorities. Each generated public/private key pair can be verified efficiently to be escrowed properly by anyone. The verification procedure does not use the private key.

Abstract: A method is provided for an escrow cryptosystem that is overhead-free, does not require a cryptographic tamper-proof hardware implementation (i.e., can be done in software), is publicly verifiable, and cannot be used subliminally to enable a shadow public key system. A shadow public key system is an unescrowed public key system that is publicly displayed in a covert fashion. The keys generated by the method are auto-recoverable and auto-certifiable (abbrev. ARC). The ARC Cryptosystem is based on a key generation mechanism that outputs a public/private key pair, and a certificate of proof that the key was generated according to the algorithm. Each generated public/private key pair can be verified efficiently to be escrowed properly by anyone. The verification procedure does not use the private key. Hence, the general public has an efficient way of making sure that any given individual's private key is escrowed properly, and the trusted authorities will be able to access the private key if needed.

Abstract: A method is provided for an escrow cryptosystem that is overhead-free, does not require a cryptographic tamper-proof hardware implementation (i.e., can be done in software), is publicly verifiable, and cannot be used subliminally to enable a shadow public key system. A shadow public key system is an unescrowed public key system that is publicly displayed in a covert fashion. The key generated by the method are auto-recoverable and auto-certifiable (abbrev. ARC). The ARC Cryptosystem is based on a key generation mechanism that outputs a public/private key pair, and a certificate of proof that the key was generated according to the algorithm. Each generated public/private key pair can be verified efficiently to be escrowed properly by anyone. The verification procedure does not use the private key. Hence, the general public has an efficient way of making sure that any given individual's private key is escrowed properly, and the trusted authorities will be able to access the private key if needed.

Abstract: A method is provided for an escrow cryptosystem combined with an unescrowed digital signature scheme that uses a single public key per user. This system is overhead-free, does not require a cryptographic tamper-proof hardware implementation (i.e., can be done in software), and is publicly verifiable. The system cannot be used subliminally to enable a shadow public key system. Namely, an unescrowed public key system that is publicly displayed in a covert fashion. The cryptosystem contains a key generation mechanism that outputs a key triplet, and a certificate of proof that the keys were generated according to the algorithm. The key triplet consists of a public key, a private decryption key, and a private signing key. Using the public key and the certificate, the triplet can be verified efficiently by anyone to have the following properties: (1) the private signing key is known to the user, and (2) the private decryption key is recoverable by the escrow authorities.

Abstract: A cryptographic key recovery system that is interoperable with existing systems for establishing keys between communicating parties. The sender uses a reversible key inversion function to generate key recovery values P, Q and (optionally) R as a function of a session key and public information, so that the session key may be regenerated from the key recovery values P, Q and (if generated) R. Key recovery values P and Q are encrypted using the respective public recovery keys of a pair of key recovery agents. The encrypted P and Q values are included along with other recovery information in a session header accompanying an encrypted message sent from the sender to the receiver. The key recovery agents may recover the P and Q values for a law enforcement agent by decrypting the encrypted P and Q values in the session header, using their respective private recovery keys corresponding to the public keys.

Abstract: A cryptographic method implemented on an electronic communication network interconnecting a plurality of terminals represents funds in a way that is secure at the issuer and secure when funds move from payer to payee and back to the issuer. The cryptographic method mints, issues, pays and redeems funds when transactions are done over the network with the flow and transaction of funds being controlled by an issuer. The method implements electronic money acquisition, transfer of money between users in an unrestricted way and in a way where fraud is impossible cryptographically, and redemption of electronic money to correct real money bank accounts. Funds are handled so that their representation enables the issuer to treat the representation as a physical monetary instrument equivalent to notes or coins.

Abstract: A cryptographic key recovery system that operates in two phases. In the first phase, the sender establishes a secret value with the receiver. For each key recovery agent, the sender generates a key-generating value as a one-way function of the secret value and encrypts the key-generating value with a public key of the key recovery agent. In the second phase, performed for a particular cryptographic session, the sender generates for each key recovery agent a key-encrypting key as a one-way function of the corresponding key-generating value and multiply encrypts the session key with the key-encrypting keys of the key recovery agents. The encrypted key-generating values and the multiply encrypted session key are transmitted together with other recovery information in a manner permitting their interception by a party seeking to recover the secret value.

Abstract: A cryptographic key recovery system for generating a cryptographic key for use by a pair of communicating parties while simultaneously providing for its recovery using one or more key recover agents. A plurality of m-bit shared key parts (P, Q) are generated which are shared with respective key recovery agents, while an n-bit nonshared key part (R) is generated that is not shared with any key recovery agent. The shared key parts (P, Q) are combined to generate an m-bit value which is concatenated with the nonshared key part (R) to generate an (m+n)-bit value from which an encryption key is generated. The cryptographic system has the effective work factor of an n-bit key to all of the key recovery agents acting in concert, but has the effective work factor of an (m+n)-bit to any other combination of third parties.

Abstract: A cryptographic key recovery system that is interoperable with existing systems for establishing keys between communicating parties. The sender uses a reversible key inversion function to generate key recovery values P, Q and (optionally) R as a function of a session key and public information, so that the session key may be regenerated from the key recovery values P, Q and (if generated) R. Key recovery values P and Q are encrypted using the respective public recovery keys of a pair of key recovery agents. The encrypted P and Q values are included along with other recovery information in a session header accompanying an encrypted message sent from the sender to the receiver. The key recovery agents may recover the P and Q values for a law enforcement agent by decrypting the encrypted P and Q values in the session header, using their respective private recovery keys corresponding to the public keys.

Abstract: A method and corresponding apparatus utilizes questioning to provide secure access control including the steps of storing information in a database; generating at least one question based upon the information stored in the data base; communicating to the user the generated question(s); receiving a response associated with the question(s), interpreting the response to determine whether the response conforms to the information upon which is based the associated question(s); and outputting an authorization status indicating whether or not the user is authorized for access according to the determination. The question(s) concerns a relationship among portions of information contained in said data base. This feature is advantageous because it protects against an eavesdropper gaining access to the service or facility and provides the capability of generating a relatively large number of different questions from a small data base.

Abstract: A method and system for detecting authorized programs within a data processing system. The present invention creates a validation structure for validating a program. The validation structure is embedded in the program and in response to an initiation of the program, a determination is made as to whether the program is an authorized program. The determination is made using the validation structure.