Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Protection at a particular protocol layer
Reexamination Certificate
1999-07-13
2001-06-19
Trammell, James P. (Department: 2161)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Protection at a particular protocol layer
C713S156000, C713S175000
Reexamination Certificate
active
06249873
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to the field of digital data processing communications systems in which a user at a workstation requests information or services from a server computer. More particularly, the invention relates to a method of and apparatus for providing a public key infrastructure via secure directory services within a computer system and/or a computer network.
BACKGROUND AND SUMMARY OF THE INVENTION
With the widespread and ever mushrooming use of network-based communications, a business world where electronic-based business transactions are the rule rather than the exception has been a longstanding vision shared by many. A major stumbling block to widespread electronic business transactions is the need to effectively deploy a secure communications system providing privacy, message integrity, non-repudiation and authenticity.
Cryptographic systems have been widely used to ensure the privacy and authenticity of messages communicated over a wide variety of different networks. Many conventional cryptosystems are not satisfactory for widespread business world deployment due to well recognized problems relating to, for example, key distribution.
Public key cryptographic systems have been advantageously utilized to solve existing cryptographic system problems including key distribution problems. Such public key cryptographic systems use a public key/private key pair and decouple the encrypting and decrypting processes such that the encrypting process key is separate and distinct from the decrypting process key. In such systems, given the knowledge of the encryption key and an encryption key that is large enough, it is not viable to compute the decryption key and thus the encryption key for users may be distributed or published. Anyone desiring to communicate with a user at a particular destination, encrypts a message under the destination user's public key. Only the destination user who retains the secret decrypting key of the public key/private key pair is able to decipher the transmitted messages.
In public key cryptographic systems, it is known that a trusted authority may create a digital message which contains a claimant's public key and the name of the claimant. A representative of the trusted authority digitally signs the digital message with the authority's own digital signature. Such a digital message, referred to as a digital certificate is transmitted along with the use of the claimant's own digital signature. See U.S. Pat. No. 4,405,829 issued to Rivest et al., which discloses exemplary methodology for a practical public key cryptographic system implementation. Also see U.S. Pat. No. 5,214,702, which describes a public key digital signature cryptographic system having enhanced digital signature certification.
Existing public key cryptography methodologies envision that electronic business transactions employ a global standard for tying the public key use to a high level global authority, using what is referred to as the X-500 standard. Not all users, however, participate in this global standard, thereby limiting the standard's practical utility.
The present methodology does not rely on a global standard. In accordance with an exemplary embodiment of the present invention, cryptographic keys may be resident in a users own directory services, while permitting users to securely communicate with each other as a result of using the distributed directory services described herein. The present invention utilizes secure distributed directory services to maintain a public key infrastructure, and does not operate in the conventional global, top-down hierarchy using a “meta-certifier”, who must certify all users in order to provide the desired level of security.
In accordance with an exemplary embodiment, users may receive digital certificates from various other users and still securely communicate with each other with sufficient security such that electronic business transactions may be culminated. The present invention incorporates the use of policy statements which efficiently permit trust levels to be applied to a user's service request based upon an analysis by the recipient of the message sender's identity via the distributed directory services system. Thus, the fact that a particular message sender is identified in a given distributed directory service using designated policy statements, permits the message recipient to determine the degree of trust to be given to a message sender.
The exemplary embodiment implements the concept that by being able to uniquely identify a client in a specific communications context, a server can assign the client with specific access rights for that context. The access rights granted to a client depend on the client's identity in that context.
Given that access rights are based on identity, the feature of being able to uniquely identify a client becomes significant. The server requires a secure and infallible method of identifying the client. The infallible method is based on using secure directory services of the nature described in the present exemplary embodiment. By securely receiving identity verification services from a directory service, the server can then determine the access rights to grant to a client. This allows a server to deliver client-sensitive information, without prior knowledge of the client.
In accordance with an exemplary embodiment of the present invention, a client initiates a secure connection with a server providing directory services. The server, tking advantage of the authentication feature in the secure communications methodology described herein, uniquely identifies the client and thus obtains the client's distinguished name (DN). The server uses the client's DN to determine what access rights to grant the client, either by looking up the client's DN in its own directory or by recursively acting as a client to another directory server that contains definitive information about that particular DN. The directory server then returns the information to the client that is specific to that client and is able to do so by taking advantage of the authentication feature provided by the secure communications methodology used herein.
In accordance with another aspect of the present invention, a client initiates a secure communication with a server. The methodology described herein is also applicable to the instance where the client and server are on the same machines so that the network described herein may be internal to the computer in this special case. The server is able to uniquely identify the client based on the authentication feature of the secure communications server as a directory service to verify the identity of the client's DN and for access control permissions to grant to the client. This communication with the directory service must be over a secure communications channel because the information passed on to the client/server communication depends on the result and verification and access rights returned by the directory service. The directory service responds to the server with verification information and access control information, particular to that client and the server is able to determine what information should be sent to the client. The server then returns either none, some or all the information requested by the client.
In an illustrative embodiment, the identities of the parties involved determine the access rights for a directory service's communications context. All requests for information made by the client, receive customized directory service responses. The peer identities are determined through the use of secure communications.
In an exemplary embodiment, the server receives the client's Distinguishing Name (DN), and then searches its directory for identification information and access control rights for this specific context. The server can act as a stand-alone server or in conjunction with other directory services on the network. A client must have a verifiable identity in order for
Csinger Andrew
Knipe Bruce
Richard Patrick
Woodward Bruce
Elisca Pierre E.
Testa Hurwitz & Thibeault LLP
Trammell James P.
Xcert Software, Inc.
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