Method and apparatus for secure password transmission and password changes

• US 6,826,686 B1
• Filed: 04/14/2000
• Issued: 11/30/2004
• Est. Priority Date: 04/14/2000
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Peyravian, Mohammad, Zunic, Nevenko
• Primary Examiner(s): Barrón, Gilberto
• Assistant Examiner(s): Zand, Kambiz
• Application Number:
  US09/549,944
• Time in Patent Office: 1,691 Days
• Field of Search: 713/168, 713/169, 713/181, 713/202
• US Class Current: 713/168
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 21/606 by securing the transmission between two devices or processes
• CPC Class Codes: H04L 63/0846 using time-dependent-passwords, e.g. periodically changing passwords
• 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 9/3234 involving additional secure or trusted devices, e.g. TPM, smartcard, USB or software token network architectures or network communication protocols for supporting authentication of entities using an additional device in a packet data network H04L63/0853
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3271 using challenge-response

Abstract

A secure method for changing a password to a new password when the passwords are being transmitted over a network is presented. The present invention does not require the use of any additional keys (such as symmetric keys or public/private key pairs) to protect the password exchanges. Moreover, the present solution does not require the use of any encryption algorithms (such as DES, RC4/RC5, etc.), it only requires the use of a collision-resistant hash function.

Claims

1. A method for securely changing an existing password associated with a user identifier (userid) on a host computer to a new password, wherein said passwords enable a user associated with said userid at a local computer to access information on said host computer across a network;

said method comprising the steps of;

sending, by the local computer, the userid and a first nonce to the host computer;

replying, by the host computer to the local computer, with a second nonce;

generating, by the local computer, a first digest of the userid and the existing password and a second digest of the userid and the new password;

creating, by the local computer, an authentication token and an authentication token mask wherein said authentication token is a hash function of the first digest, first nonce and second nonce, and said token mask is a hash function of the second digest, first nonce plus a predetermined value and the second nonce;

generating, by the local computer, a protected digest by exclusive-oring the second digest with the token mask;

sending, by the local computer to the host computer, the userid, authentication token and the protected digest;

verifying, by the host computer, the validity of the authentication token; and

,

accepting the new password to replace the existing password if the authentication token is valid.

2. A computer program product for securely changing an existing password associated with a user identifier (userid) on a host computer to a new password, wherein said passwords enable a user associated with said userid at a local computer to access information on said host computer across a network;

said computer program product comprising;

computer readable programming for sending, by the local computer, the userid and a first nonce to the host computer;

computer readable programming for replying, by the host computer to the local computer, with a second nonce;

computer readable programming for generating, by the local computer, a first digest of the userid and the existing password and a second digest of the userid and the new password;

computer readable programming for creating, by the local computer, an authentication token and an authentication token mask wherein said authentication token is a hash function of the first digest, first nonce and second nonce, and said token mask is a hash function of the second digest, first nonce plus a predetermined value and the second nonce;

computer readable programming for generating, by the local computer, a protected digest by exclusive-oring the second digest with the token mask;

computer readable programming for sending, by the local computer to the host computer, the userid, authentication token and the protected digest;

computer readable programming for verifying, by the host computer, the validity of the authentication token; and

,

computer readable programming for accepting the new password to replace the existing password if the authentication token is valid.

3. A computer program product as claimed in claim 2 wherein said first and second digests are calculated by performing a hash function of the userids and respective passwords.

4. A computer program product as claimed in claim 2 or 3 wherein said hash function is a collision-resistant, one-way hash.