In this white paper, we describe the basic characteristics of DES and triple-DES and look at the security properties that a financial transaction system will want to achieve. We then look at the problems related with a migration from DES to triple-DES; enumerating and discussing several points that we suggest should be considered.
Abstract
Financial institutions are performing large scale migrations of their systems from DES to triple-DES. In this white paper, we describe the basic characteristics of DES and triple-DES and look at the security properties that a financial transaction system will want to achieve. We then look at the problems related with a migration from DES to triple-DES; enumerating and discussing several points that we suggest should be considered. Finally, we give some suggestions that will help ease the problems of migration. Table of content 1. INTRODUCTION ..................................................................................................3 2. SINGLE DES AND TRIPLE-DES.........................................................................3 3. SECURITY PROPERTIES WANTED...................................................................4 4. MIGRATION ISSUES ...........................................................................................5
4.1. DES is the weakest link ......................................................................................5
4.2. The algorithm itself.............................................................................................6
4.3. Key blocks ...........................................................................................................6
4.4. Hardware update.................................................................................................7
4.5. Software/Firmware update.................................................................................7
4.6. Payment application database ..........................................................................7
4.7. Key Management ................................................................................................7
4.8. Old vulnerabilities...............................................................................................8 5. EASING THE MIGRATION ..................................................................................8 6. CONCLUSION......................................................................................................9 Why Migrating to Triple DES is Not Easy
1. Introduction DES, the Data Encryption Standard, is a cryptographic algorithm that was standardized in 1977 by the National Institute of Science and Technology (NIST). When the financial industry started to deploy ATMs, they opted for DES for securing transactions. This choice was reinforced by the development of X9 standards for financial transactions that were based on DES. DES has stood the test of time, no attack against this encryption algorithm in practice has been better than brute forcing the key space. However, DES uses short keys, with current technology the key space (of size 256 ) can be exhausted in around 56 hours using one single machine worth less than 250 000 US dollars, or in 22 hours with the combined help of a network of about 100 000 personal computers. This means that single DES is no longer secure. On the other hand, triple-DES, as defined in ANSI 9.52, is considered to be secure. Indeed, NIST renewed the DES standard in 1983 and 1988, in 1993 it renewed it with hesitation and controversy and in 1999 DES was to be used only in legacy systems. NIST, in 1999, standardized triple-DES, based on ANSI 9.52. Triple-DES is a secure replacement for single DES, it is not currently feasible to exhaustively search the key space of triple-DES, nor will it be in the near future unless drastic unpredictable technological and/or cryptanalysis advancements occur. In 1993, the financial industry had started replacing DES by triple-DES for the confidentiality of keys residing in cryptographic processors. In 1999, with the concordance of NIST no longer approving single DES, the financial industry started planning a migration, which consists of replacing single DES with triple-DES in all its systems wherever single DES is used. This migration plan however places the industry, which uses single DES widely, in a challenging position. As will be discussed in this document, the process of migrating from single DES to triple-DES is not as simp... [download for more]
