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Demystifying Cryptography with OpenSSL 3.0

You're reading from   Demystifying Cryptography with OpenSSL 3.0 Discover the best techniques to enhance your network security with OpenSSL 3.0

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Product type Paperback
Published in Oct 2022
Publisher Packt
ISBN-13 9781800560345
Length 342 pages
Edition 1st Edition
Languages
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Author (1):
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Alexei Khlebnikov Alexei Khlebnikov
Author Profile Icon Alexei Khlebnikov
Alexei Khlebnikov
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Toc

Table of Contents (20) Chapters Close

Preface 1. Part 1: Introduction
2. Chapter 1: OpenSSL and Other SSL/TLS Libraries FREE CHAPTER 3. Part 2: Symmetric Cryptography
4. Chapter 2: Symmetric Encryption and Decryption 5. Chapter 3: Message Digests 6. Chapter 4: MAC and HMAC 7. Chapter 5: Derivation of an Encryption Key from a Password 8. Part 3: Asymmetric Cryptography and Certificates
9. Chapter 6: Asymmetric Encryption and Decryption 10. Chapter 7: Digital Signatures and Their Verification 11. Chapter 8: X.509 Certificates and PKI 12. Part 4: TLS Connections and Secure Communication
13. Chapter 9: Establishing TLS Connections and Sending Data over Them 14. Chapter 10: Using X.509 Certificates in TLS 15. Chapter 11: Special Usages of TLS 16. Part 5: Running a Mini-CA
17. Chapter 12: Running a Mini-CA 18. Index 19. Other Books You May Enjoy

Why are message digests needed?

Message digests have many applications. The most obvious one is data integrity verification.

Data integrity verification

When you’re downloading software from the internet, you will often find the message digest of the distribution package close to the download link. As an example, look at the OpenSSL download page at https://www.openssl.org/source/:

Figure 3.1 – The OpenSSL download page fragment

Next to the download link, you will see links called SHA256 and SHA1. These contain the message digests for the corresponding .tar.gz files. When the required .tar.gz file is downloaded, the digest of the downloaded file can be calculated and compared to the expected digest. If the digests match, then the file may not have been corrupted or otherwise changed while being transmitted and saved. If the file was changed, the calculated digest would look very different from the expected digest, because of the avalanche...

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