Secure Programming Cookbook for C and C++: Recipes for Cryptography, Authentication, Input Validation & More

by John Viega, Matt Messier

Overview

Password sniffing, spoofing, buffer overflows, and denial of service: these are only a few of the attacks on today's computer systems and networks. At the root of this epidemic is poorly written, poorly tested, and insecure code that puts everyone at risk. Clearly, today's developers need help figuring out how to write code that attackers won't be able to exploit. But writing such code is surprisingly difficult.

Secure Programming Cookbook for C and C++ is an important new resource for developers serious about writing secure code. It contains a wealth of solutions to problems faced by those who care about the security of their applications. It covers a wide range of topics, including safe initialization, access control, input validation, symmetric and public key cryptography, cryptographic hashes and MACs, authentication and key exchange, PKI, random numbers, and anti-tampering. The rich set of code samples provided in the book's more than 200 recipes will help programmers secure the C and C++ programs they write for both Unix® (including Linux®) and Windows® environments. Readers will learn:

• How to avoid common programming errors, such as buffer overflows, race conditions, and format string problems
• How to properly SSL-enable applications
• How to create secure channels for client-server communication without SSL
• How to integrate Public Key Infrastructure (PKI) into applications
• Best practices for using cryptography properly
• Techniques and strategies for properly validating input to programs
• How to launch programs securely
• How to use file access mechanisms properly
• Techniques for protecting applications from reverse engineering

The book's web site supplements the book by providing a place to post new recipes, including those written in additional languages like Perl, Java, and Python. Monthly prizes will reward the best recipes submitted by readers.

Secure Programming Cookbook for C and C++ is destined to become an essential part of any developer's library, a code companion developers will turn to again and again as they seek to protect their systems from attackers and reduce the risks they face in today's dangerous world.

Product Details

ISBN-13:	9780596552183
Publisher:	O'Reilly Media, Incorporated
Publication date:	07/14/2003
Sold by:	Barnes & Noble
Format:	eBook
Pages:	792
File size:	5 MB

About the Author

John Viega, Founder and Chief Scientist of Secure Software (www.securesoftware.com), is a well-known security expert, and coauthor of Building Secure Software (Addison-Wesley) and Network Security with OpenSSL (O'Reilly). John is responsible for numerous software security tools, and is the original author of Mailman, the GNU mailing list manager. He holds a B.A. and M.S. in Computer Science from the University of Virginia. Mr. Viega is also an Adjunct Professor of Computer Science at Virginia Tech (Blacksburg, VA) and a Senior Policy Researcher at the Cyberspace Policy Institute, and he serves on the Technical Advisory Board for the Open Web Applications Security Project. He also founded a Washington, D.C. area security interest group that conducts monthly lectures presented by leading experts in the field. He is the author or coauthor of nearly 80 technical publications, including numerous refereed research papers and trade articles.

Matt Messier, Director of Engineering at Secure Software, is a security authority who has been programming for nearly two decades. Besides coauthoring Network Security with OpenSSL, Matt coauthored the Safe C String Library, RATS, and EGADS, an Entropy Gathering and Distribution System used for securely seeding pseudo-random number generators. Prior to joining Secure Software, Matt worked for IBM and Lotus, on source and assembly level debugging techniques, and operating system concepts.

Table of Contents

Foreword; Preface; More Than Just a Book; We Can't Do It All; Organization of This Book; Recipe Compatibility; Conventions Used in This Book; Comments and Questions; Acknowledgments; Chapter 1: Safe Initialization; 1.1 Sanitizing the Environment; 1.2 Restricting Privileges on Windows; 1.3 Dropping Privileges in setuid Programs; 1.4 Limiting Risk with Privilege Separation; 1.5 Managing File Descriptors Safely; 1.6 Creating a Child Process Securely; 1.7 Executing External Programs Securely; 1.8 Executing External Programs Securely; 1.9 Disabling Memory Dumps in the Event of a Crash; Chapter 2: Access Control; 2.1 Understanding the Unix Access Control Model; 2.2 Understanding the Windows Access Control Model; 2.3 Determining Whether a User Has Access to a File on Unix; 2.4 Determining Whether a Directory Is Secure; 2.5 Erasing Files Securely; 2.6 Accessing File Information Securely; 2.7 Restricting Access Permissions for New Files on Unix; 2.8 Locking Files; 2.9 Synchronizing Resource Access Across Processes on Unix; 2.10 Synchronizing Resource Access Across Processes on Windows; 2.11 Creating Files for Temporary Use; 2.12 Restricting Filesystem Access on Unix; 2.13 Restricting Filesystem and Network Access on FreeBSD; Chapter 3: Input Validation; 3.1 Understanding Basic Data Validation Techniques; 3.2 Preventing Attacks on Formatting Functions; 3.3 Preventing Buffer Overflows; 3.4 Using the SafeStr Library; 3.5 Preventing Integer Coercion and Wrap-Around Problems; 3.6 Using Environment Variables Securely; 3.7 Validating Filenames and Paths; 3.8 Evaluating URL Encodings; 3.9 Validating Email Addresses; 3.10 Preventing Cross-Site Scripting; 3.11 Preventing SQL Injection Attacks; 3.12 Detecting Illegal UTF-8 Characters; 3.13 Preventing File Descriptor Overflows When Using select(); Chapter 4: Symmetric Cryptography Fundamentals; 4.1 Representing Keys for Use in Cryptographic Algorithms; 4.2 Generating Random Symmetric Keys; 4.3 Representing Binary Keys (or Other Raw Data) as Hexadecimal; 4.4 Turning ASCII Hex Keys (or Other ASCII Hex Data) into Binary; 4.5 Performing Base64 Encoding; 4.6 Performing Base64 Decoding; 4.7 Representing Keys (or Other Binary Data) as English Text; 4.8 Converting Text Keys to Binary Keys; 4.9 Using Salts, Nonces, and Initialization Vectors; 4.10 Deriving Symmetric Keys from a Password; 4.11 Algorithmically Generating Symmetric Keys from One Base Secret; 4.12 Encrypting in a Single Reduced Character Set; 4.13 Managing Key Material Securely; 4.14 Timing Cryptographic Primitives; Chapter 5: Symmetric Encryption; 5.1 Deciding Whether to Use Multiple Encryption Algorithms; 5.2 Figuring Out Which Encryption Algorithm Is Best; 5.3 Selecting an Appropriate Key Length; 5.4 Selecting a Cipher Mode; 5.5 Using a Raw Block Cipher; 5.6 Using a Generic CBC Mode Implementation; 5.7 Using a Generic CFB Mode Implementation; 5.8 Using a Generic OFB Mode Implementation; 5.9 Using a Generic CTR Mode Implementation; 5.10 Using CWC Mode; 5.11 Manually Adding and Checking Cipher Padding; 5.12 Precomputing Keystream in OFB, CTR, CCM, or CWC Modes (or with Stream Ciphers); 5.13 Parallelizing Encryption and Decryption in Modes That Allow It (Without Breaking Compatibility); 5.14 Parallelizing Encryption and Decryption in Arbitrary Modes (Breaking Compatibility); 5.15 Performing File or Disk Encryption; 5.16 Using a High-Level, Error-Resistant Encryption and Decryption API; 5.17 Performing Block Cipher Setup (for CBC, CFB, OFB, and ECB Modes) in OpenSSL; 5.18 Using Variable Key-Length Ciphers in OpenSSL; 5.19 Disabling Cipher Padding in OpenSSL in CBC Mode; 5.20 Performing Additional Cipher Setup in OpenSSL; 5.21 Querying Cipher Configuration Properties in OpenSSL; 5.22 Performing Low-Level Encryption and Decryption with OpenSSL; 5.23 Setting Up and Using RC4; 5.24 Using One-Time Pads; 5.25 Using Symmetric Encryption with Microsoft's CryptoAPI; 5.26 Creating a CryptoAPI Key Object from Raw Key Data; 5.27 Extracting Raw Key Data from a CryptoAPI Key Object; Chapter 6: Hashes and Message Authentication; 6.1 Understanding the Basics of Hashes and MACs; 6.2 Deciding Whether to Support Multiple Message Digests or MACs; 6.3 Choosing a Cryptographic Hash Algorithm; 6.4 Choosing a Message Authentication Code; 6.5 Incrementally Hashing Data; 6.6 Hashing a Single String; 6.7 Using a Cryptographic Hash; 6.8 Using a Nonce to Protect Against Birthday Attacks; 6.9 Checking Message Integrity; 6.10 Using HMAC; 6.11 Using OMAC (a Simple Block Cipher-Based MAC); 6.12 Using HMAC or OMAC with a Nonce; 6.13 Using a MAC That's Reasonably Fast in Software and Hardware; 6.14 Using a MAC That's Optimized for Software Speed; 6.15 Constructing a Hash Function from a Block Cipher; 6.16 Using a Block Cipher to Build a Full-Strength Hash Function; 6.17 Using Smaller MAC Tags; 6.18 Making Encryption and Message Integrity Work Together; 6.19 Making Your Own MAC; 6.20 Encrypting with a Hash Function; 6.21 Securely Authenticating a MAC (Thwarting Capture Replay Attacks); 6.22 Parallelizing MACs; Chapter 7: Public Key Cryptography; 7.1 Determining When to Use Public Key Cryptography; 7.2 Selecting a Public Key Algorithm; 7.3 Selecting Public Key Sizes; 7.4 Manipulating Big Numbers; 7.5 Generating a Prime Number (Testing for Primality); 7.6 Generating an RSA Key Pair; 7.7 Disentangling the Public and Private Keys in OpenSSL; 7.8 Converting Binary Strings to Integers for Use with RSA; 7.9 Converting Integers into Binary Strings for Use with RSA; 7.10 Performing Raw Encryption with an RSA Public Key; 7.11 Performing Raw Decryption Using an RSA Private Key; 7.12 Signing Data Using an RSA Private Key; 7.13 Verifying Signed Data Using an RSA Public Key; 7.14 Securely Signing and Encrypting with RSA; 7.15 Using the Digital Signature Algorithm (DSA); 7.16 Representing Public Keys and Certificates in Binary (DER Encoding); 7.17 Representing Keys and Certificates in Plaintext (PEM Encoding); Chapter 8: Authentication and Key Exchange; 8.1 Choosing an Authentication Method; 8.2 Getting User and Group Information on Unix; 8.3 Getting User and Group Information on Windows; 8.4 Restricting Access Based on Hostname or IP Address; 8.5 Generating Random Passwords and Passphrases; 8.6 Testing the Strength of Passwords; 8.7 Prompting for a Password; 8.8 Throttling Failed Authentication Attempts; 8.9 Performing Password-Based Authentication with crypt(); 8.10 Performing Password-Based Authentication with MD5-MCF; 8.11 Performing Password-Based Authentication with PBKDF2; 8.12 Authenticating with PAM; 8.13 Authenticating with Kerberos; 8.14 Authenticating with HTTP Cookies; 8.15 Performing Password-Based Authentication and Key Exchange; 8.16 Performing Authenticated Key Exchange Using RSA; 8.17 Using Basic Diffie-Hellman Key Agreement; 8.18 Using Diffie-Hellman and DSA Together; 8.19 Minimizing the Window of Vulnerability When Authenticating Without a PKI; 8.20 Providing Forward Secrecy in a Symmetric System; 8.21 Ensuring Forward Secrecy in a Public Key System; 8.22 Confirming Requests via Email; Chapter 9: Networking; 9.1 Creating an SSL Client; 9.2 Creating an SSL Server; 9.3 Using Session Caching to Make SSL Servers More Efficient; 9.4 Securing Web Communication on Windows Using the WinInet API; 9.5 Enabling SSL without Modifying Source Code; 9.6 Using Kerberos Encryption; 9.7 Performing Interprocess Communication Using Sockets; 9.8 Performing Authentication with Unix Domain Sockets; 9.9 Performing Session ID Management; 9.10 Securing Database Connections; 9.11 Using a Virtual Private Network to Secure Network Connections; 9.12 Building an Authenticated Secure Channel Without SSL; Chapter 10: Public Key Infrastructure; 10.1 Understanding Public Key Infrastructure (PKI); 10.2 Obtaining a Certificate; 10.3 Using Root Certificates; 10.4 Understanding X.509 Certificate Verification Methodology; 10.5 Performing X.509 Certificate Verification with OpenSSL; 10.6 Performing X.509 Certificate Verification with CryptoAPI; 10.7 Verifying an SSL Peer's Certificate; 10.8 Adding Hostname Checking to Certificate Verification; 10.9 Using a Whitelist to Verify Certificates; 10.10 Obtaining Certificate Revocation Lists with OpenSSL; 10.11 Obtaining CRLs with CryptoAPI; 10.12 Checking Revocation Status via OCSP with OpenSSL; Chapter 11: Random Numbers; 11.1 Determining What Kind of Random Numbers to Use; 11.2 Using a Generic API for Randomness and Entropy; 11.3 Using the Standard Unix Randomness Infrastructure; 11.4 Using the Standard Windows Randomness Infrastructure; 11.5 Using an Application-Level Generator; 11.6 Reseeding a Pseudo-Random Number Generator; 11.7 Using an Entropy Gathering Daemon-Compatible Solution; 11.8 Getting Entropy or Pseudo-Randomness Using EGADS; 11.9 Using the OpenSSL Random Number API; 11.10 Getting Random Integers; 11.11 Getting a Random Integer in a Range; 11.12 Getting a Random Floating-Point Value with Uniform Distribution; 11.13 Getting Floating-Point Values with Nonuniform Distributions; 11.14 Getting a Random Printable ASCII String; 11.15 Shuffling Fairly; 11.16 Compressing Data with Entropy into a Fixed-Size Seed; 11.17 Getting Entropy at Startup; 11.18 Statistically Testing Random Numbers; 11.19 Performing Entropy Estimation and Management; 11.20 Gathering Entropy from the Keyboard; 11.21 Gathering Entropy from Mouse Events on Windows; 11.22 Gathering Entropy from Thread Timings; 11.23 Gathering Entropy from System State; Chapter 12: Anti-Tampering; 12.1 Understanding the Problem of Software Protection; 12.2 Detecting Modification; 12.3 Obfuscating Code; 12.4 Performing Bit and Byte Obfuscation; 12.5 Performing Constant Transforms on Variables; 12.6 Merging Scalar Variables; 12.7 Splitting Variables; 12.8 Disguising Boolean Values; 12.9 Using Function Pointers; 12.10 Restructuring Arrays; 12.11 Hiding Strings; 12.12 Detecting Debuggers; 12.13 Detecting Unix Debuggers; 12.14 Detecting Windows Debuggers; 12.15 Detecting SoftICE; 12.16 Countering Disassembly; 12.17 Using Self-Modifying Code; Chapter 13: Other Topics; 13.1 Performing Error Handling; 13.2 Erasing Data from Memory Securely; 13.3 Preventing Memory from Being Paged to Disk; 13.4 Using Variable Arguments Properly; 13.5 Performing Proper Signal Handling; 13.6 Protecting against Shatter Attacks on Windows; 13.7 Guarding Against Spawning Too Many Threads; 13.8 Guarding Against Creating Too Many Network Sockets; 13.9 Guarding Against Resource Starvation Attacks on Unix; 13.10 Guarding Against Resource Starvation Attacks on Windows; 13.11 Following Best Practices for Audit Logging; Colophon;