# Understanding Cryptography: A Textbook for Students and Practitioners

## Christof Paar, Jan Pelzl

Language: English

Pages: 372

ISBN: 3642041000

Format: PDF / Kindle (mobi) / ePub

Cryptography is now ubiquitous – moving beyond the traditional environments, such as government communications and banking systems, we see cryptographic techniques realized in Web browsers, e-mail programs, cell phones, manufacturing systems, embedded software, smart buildings, cars, and even medical implants. Today's designers need a comprehensive understanding of applied cryptography.

After an introduction to cryptography and data security, the authors explain the main techniques in modern cryptography, with chapters addressing stream ciphers, the Data Encryption Standard (DES) and 3DES, the Advanced Encryption Standard (AES), block ciphers, the RSA cryptosystem, public-key cryptosystems based on the discrete logarithm problem, elliptic-curve cryptography (ECC), digital signatures, hash functions, Message Authentication Codes (MACs), and methods for key establishment, including certificates and public-key infrastructure (PKI). Throughout the book, the authors focus on communicating the essentials and keeping the mathematics to a minimum, and they move quickly from explaining the foundations to describing practical implementations, including recent topics such as lightweight ciphers for RFIDs and mobile devices, and current key-length recommendations.

The authors have considerable experience teaching applied cryptography to engineering and computer science students and to professionals, and they make extensive use of examples, problems, and chapter reviews, while the book’s website offers slides, projects and links to further resources. This is a suitable textbook for graduate and advanced undergraduate courses and also for self-study by engineers.

The Computer and the Brain (3rd Edition) (The Silliman Memorial Lectures Series)

Core Software Security: Security at the Source

Software and Hardware . . . . . . . . . . . . . . . . . . . . . 252 9.6 Discussion and Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 9.7 Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 10 Digital Signatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Of the ECB mode is that it encrypts highly deterministically. This means that identical plaintext blocks result in identical ciphertext blocks, as long as the key does not change. The ECB mode can be viewed as a gigantic code book — hence the mode’s name — which maps every input to a certain output. Of course, if the key is changed the entire code book changes, but as long as the key is static the book is fixed. This has several undesirable consequences. First, an attacker recognizes if the same.

Whitening against DES, which we’ll call DESA: DESAk,k1 (x) = DESk (x) ⊕ k1 . Even though the method looks similar to key whitening, it hardly adds to the security. Your task is to show that breaking the scheme is roughly as difficult as a brute-force attack against single DES. Assume you have a few pairs of plaintext– ciphertext. Chapter 6 Introduction to Public-Key Cryptography Before we learn about the basics of public-key cryptography, let us recall that the term public-key cryptography is.

#SQ = t #MUL = 0.5t Because the exponents used in cryptography have often good random properties, assuming that half of their bits have the value one is often a valid approximation. Example 7.5. How many operations are required on average for an exponentiation with a 1024-bit exponent? Straightforward exponentiation takes 21024 ≈ 10300 multiplications. That is completely impossible, no matter what computer resources we might have at hand. However, the square-and-multiply algorithm requires only.

Computationally secure against a brute-force attack. 8 1 Introduction to Cryptography and Data Security Let’s determine the key space of the substitution cipher: When choosing the replacement for the first letter A, we randomly choose one letter from the 26 letters of the alphabet (in the example above we chose k). The replacement for the next alphabet letter B was randomly chosen from the remaining 25 letters, etc. Thus there exist the following number of different substitution tables: key.