Method and apparatus for protecting the confidentiality of passwords in a distributed data processing system

• US 5,418,854 A
• Filed: 04/28/1992
• Issued: 05/23/1995
• Est. Priority Date: 04/28/1992
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Gasser, Morrie, Kaufman, Charles W., Lampson, Butler W., Tardo, Joseph J., Alagappan, Kannan
• Primary Examiner(s): Bowler, Alyssa H.
• Assistant Examiner(s): FOLLANSBEE, JOHN A
• Application Number:
  US07/875,050
• Time in Patent Office: 1,120 Days
• Field of Search: 395/800, 380/30, 380/25, 380/4, 380/23, 380/49
• US Class Current: 713/156
• CPC Class Codes: G06F 21/335 for accessing specific resources, e.g. using Kerberos tickets
• CPC Class Codes: G06F 21/79 in semiconductor storage media, e.g. directly-addressable memories
• CPC Class Codes: G06F 21/85 interconnection devices, e.g. bus-connected or in-line devices
• CPC Class Codes: G06F 2221/2143 Clearing memory, e.g. to prevent the data from being stolen
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/0825 using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates
• CPC Class Codes: H04L 9/0863 involving passwords or one-time passwords network architectures or network communication protocols for using one-time keys in a packet data network H04L63/067
• CPC Class Codes: H04L 9/3226 using a predetermined code, e.g. password, passphrase or PIN network architectures or network communication protocols for supporting authentication of entities using passwords in a packet data network H04L63/083
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions

Abstract

Apparatus for protecting the confidentiality of a user'"'"'s password during a remote login authentication exchange between a user node and a directory service node of a distributed, public key cryptography system includes a specialized server application functioning as an intermediary agent for the login procedure. The login agent has responsibility for approving the user'"'"'s login attempt and distributing a private key to the user. However, the login agent is not trusted with the user'"'"'s password and is therefore a "semi-trusted" node. In another aspect of the invention, a login protocol enables remote authentication of the user password without transmitting the password over the network.

Claims

1. In a public key, distributed data processing network system including a plurality of nodes interconnected by a communications medium, said nodes including a login agent (LA) node, a user node and a central certificate storage (CSS) node, a method for authenticating a user to said network using a password and username entered during a login procedure, said method also protecting the confidentiality of said password used to acquire a private key of said user to enable access to said nodes, said method comprising the steps of:

computing a first and a second hash total from said password at said user node using a first and a second hash algorithm, respectively, and generating a nonce key at said user node;

encrypting, at said user node, said second hash total and said nonce key using a public key of said LA node to create an encrypted message, and forwarding said encrypted message from said user node to said LA node;

decrypting said encrypted message at said LA node using a private key of said LA node to obtain said second hash total and said nonce key;

acquiring, at said LA node, a doubly-encrypted credential from said CSS node, said doubly-encrypted credential comprising a credential of said user private key encrypted with a first stored hash total computed from said password to form an encrypted credential, said encrypted credential being appended to a second stored hash total computed from said password and thereafter encrypted under said public key of said LA node;

decrypting said doubly-encrypted credential at said LA node to obtain said encrypted credential and said second stored hash total, and further comparing said second stored hash total with said second hash total at said LA node;

encrypting said encrypted user private key with said nonce key at said LA node when said hash totals match to create a return message, and forwarding said return message from said LA node to said user node;

decrypting said return message at said user node using said nonce key to obtain said private key encrypted with said stored first hash number, and further decrypting, at said user node, said private key encrypted with said stored first hash number with said first hash number to obtain said private key, thereby protecting the confidentiality of said password during said login procedure.

2. The method of claim 1 wherein the step of forwarding said encrypted message further comprises the step of forwarding said username from said user node to said LA node.

3. The method of claim 2 wherein said step of acquiring said doubly-encrypted credential further comprises the steps of:

forwarding said username from said LA node to said CSS node;

at said CSS node, comparing said username to names located in a directory service and obtaining said doubly-encrypted credential when said username matches one of said names in said directory service; and

forwarding said doubly-encrypted credential from said CSS node to said LA node.

4. In a public key, distributed data processing network system including a plurality of nodes interconnected by a communications medium, said nodes including a login agent (LA) node, a user node and a central certificate storage (CSS) node, an arrangement for authenticating a user to said network using a password and username entered during a login procedure, said arrangement also protecting the confidentiality of said password used to acquire a private key of said user to enable access to said nodes, said arrangement comprising:

user node computing means for computing a first and a second hash total from said password using a first and a second hash algorithm, respectively, and user node generating means for generating a nonce key;

user node encrypting means for encrypting said second hash total and said nonce key using a public key of said LA node to create an encrypted message, and user node forwarding means for forwarding said encrypted message to said LA node;

LA node decrypting means for decrypting said encrypted message using a private key of said LA node to obtain said second hash total and said nonce key;

LA node acquiring means for acquiring a doubly-encrypted credential comprising a credential of said user private key encrypted with a first stored hash total computed from said password to form an encrypted credential, said encrypted credential being appended to a second stored hash total computed from said password and thereafter encrypted under said public key of said LA node;

said LA node decrypting means for decrypting said doubly-encrypted credential to obtain said encrypted credential and said second stored hash total, and LA node comparing means for comparing said second stored hash total with said second hash total;

LA node encrypting means for encrypting said encrypted user private key with said nonce key when said hash totals match to create a return message, and LA node forwarding means for forwarding said return message to said user node;

user node decrypting means for decrypting said return message using said nonce key to obtain said private key encrypted with said stored first hash number, said user node decrytping means further decrypting said private key encrypted with said stored first hash number with said first hash number to obtain said private key, thereby protecting the confidentiality of said password during said login procedure.

5. The arrangement of claim 4 wherein said user node computing means and user node generating means comprises a first processor means and a first memory means of said user node,

6. The arrangement of claim 5 wherein said user node encrypting means comprises said first processor means and said first memory means.

7. The arrangment of claim 6 wherein said LA node decrypting means for decrypting said encrypted message comprises a second processor means and a second memory means of said LA node.

8. The arrangement of claim 7 wherein said LA node decrypting means for decrypting said doubly-encrypted credential and said LA node comparing means for comparing said second hash totals comprises said second processor means and said second memory means.

9. The arrangement of claim 8 wherein said LA node encrypting means for encrypting said user private key with said nonce key comprises said second processor means and said second memory means.

10. The arrangement of claim 9 wherein said user node decrypting means for decrypting said return message comprises said first processor means and said first memory means.

11. The arrangment of claim 4 wherein said user node forwarding means further comprises user node forwarding means for forwarding said username to said LA node.

12. The arrangment of claim 11 wherein said LA node acquiring means further comprises:

LA node forwarding means for forwarding said username to said CSS node;

CSS node comparing means for comparing said username to names located in a directory service and CSS node obtaining means for obtaining said doubly-encrypted credential when said username matches one of said names in said directory service; and

CSS node forwarding means for forwarding said doubly-encrypted credential to said LA node.

13. The arrangement of claim 12 wherein said CSS node comparing means comprises a third processor means of said CSS node.