Rainbow table

About: Rainbow table is a research topic. Over the lifetime, 488 publications have been published within this topic receiving 11528 citations.

Secure software registration and integrity assessment in a computer system

Abstract: A method for providing secure registration and integrity assessment of software in a computer system is disclosed. A secure hash table is created containing a list of secure programs that the user wants to validate prior to execution. The table contains a secure hash value (i.e., a value generated by modification detection code) for each of these programs as originally installed on the computer system. This hash table is stored in protected memory that can only be accessed when the computer system is in system management mode. Following an attempt to execute a secured program, a system management interrupt is generated. An SMI handler then generates a current hash value for the program to be executed. In the event that the current hash value matches the stored hash value, the integrity of the program is guaranteed and it is loaded into memory and executed. If the two values do not match, the user is alerted to the discrepancy and may be given the option to update or override the stored hash value by entering an administrative password.

Reverse-engineering a cryptographic RFID tag

Abstract: The security of embedded devices often relies on the secrecy of proprietary cryptographic algorithms. These algorithms and their weaknesses are frequently disclosed through reverse-engineering software, but it is commonly thought to be too expensive to reconstruct designs from a hardware implementation alone. This paper challenges that belief by presenting an approach to reverse-engineering a cipher from a silicon implementation. Using this mostly automated approach, we reveal a cipher from an RFID tag that is not known to have a software or micro-code implementation. We reconstruct the cipher from the widely used Mifare Classic RFID tag by using a combination of image analysis of circuits and protocol analysis. Our analysis reveals that the security of the tag is even below the level that its 48-bit key length suggests due to a number of design flaws. Weak random numbers and a weakness in the authentication protocol allow for pre-computed rainbow tables to be used to find any key in a matter of seconds. Our approach of deducing functionality from circuit images is mostly automated, hence it is also feasible for large chips. The assumption that algorithms can be kept secret should therefore to be avoided for any type of silicon chip.

User authentication system for authenticating an authorized user of an IC card

Abstract: An user authentication system for authenticating a user using an IC card in conjunction with a portable terminal used to generate a one-time password and a server used to generate a corresponding one-time password for user authentication. The IC card contains a secret key for generating a one-time password and predetermined random numbers. The portable terminal contains a card receiver for receiving the IC card, a random number memory for reading and storing, and then deleting the random numbers of the IC card, a first password generator for generating a one-time password by the secret key of the IC card and the random number, a first random number changer for changing the random number stored in the random number memory into a predetermined value and storing the changed value in the random number storing portion, and a display for displaying the processed results of the terminal and the server. The server includes a secret key memory for storing a secret key and a random number, a second password generator for generating a one-time password, a second random number changer for storing a random number value identical to the random number value of the terminal, a password receiver for receiving the one-time password of the terminal, a password verifier for verifying the password to authenticate the user. As a result, it is possible to raise the security level by using a one-time password in which a different password is used each time a user is authenticated, and to save costs by generating a one-time password for various services with a single terminal.

Distributed authentication system and method

Abstract: An authentication system for a distributed network having multiple clients and a server enables a user to log on at any one of the clients with a password and receive his/her associated public/private key pair. The client computes a hash of the user ID to produce a first hash value H(ID) and a hash of the user ID concatenated with the user password P to produce a second hash value H(ID/P). The client constructs a message M containing the hash value H(ID), the hash value H(ID/P), and a randomly generated session key SK. The client encrypts the message M using the server's public key and sends the encrypted message to the server. The server decrypts the message using its private key to recover the message M. The server initially checks to see if the hash values are subject to a hostile cryptographic attack. If the check is negative, the server generates key source material S as a function of the hash value H(ID), the hash value H(ID/P), and a private value that is confidential to the server. The server encrypts the key source material S using the session key SK received in the message M and sends the encrypted key source material S to the client. The client decrypts the key source material using the session key SK to recover the key source material S. The client then constructs a public/private key pair unique to the user from the user ID, the user password, and the key source material S. More particularly, one implementation involves passing the hash value H(ID), the hash value H(ID/P), the raw password P, and the key source material S through a random number generator to produce two large, relatively prime numbers p and q which are used in an RSA public key system to generate a public/private key pair.

A user authentication scheme not requiring secrecy in the computer

Abstract: In many computer operating systems a user authenticates himself by entering a secret password known solely to himself and the system. The system compares this password with one recorded in a Password Table which is available to only the authentication program. The integrity of the system depends on keeping the table secret. In this paper a password scheme is presented which does not require secrecy in the computer. All aspects of the system, including all relevant code and data bases, may be known by anyone attempting to intrude.The scheme is based on using a function H which the would-be intruder is unable to invert. This function is applied to the user's password and the result compared to a table entry, a match being interpreted as authentication of the user. The intruder may know all about H and have access to the table, but he can penetrate the system only if he can invert H to determine an input that produces a given output.This paper discusses issues surrounding selection of a suitable H. Two different plausible arguments are given that penetration would be exceedingly difficult, and it is then argued that more rigorous results are unlikely. Finally, some human engineering problems relating to the scheme are discussed.