https://signal-and-syntax.com/tags/cryptography/Recent content in Cryptography on Signal & SyntaxHugoen-usFri, 28 Nov 2025 06:00:00 -0700https://signal-and-syntax.com/posts/birthday-paradox/Fri, 28 Nov 2025 06:00:00 -0700https://signal-and-syntax.com/posts/birthday-paradox/You generate a UUID. It’s 128 bits total, with 122 bits of randomness ( Davis et al., 2024 ). That’s 340 undecillion possible values. Collision-proof, right? Your system generates a million IDs per second. Still safe? What about a billion? As I like to say, common sense and intuition are the enemies of science. Common sense tells you that with 340,000,000,000,000,000,000,000,000,000,000,000,000 possible values, you’d need to generate at least trillions before worrying about duplicates.https://signal-and-syntax.com/posts/hash-collisions/Mon, 17 Nov 2025 06:00:00 -0700https://signal-and-syntax.com/posts/hash-collisions/In 2017, Google researchers generated two different PDF files with identical SHA-1 hashes, finally proving what cryptographers had warned about for years: hash functions don’t create truly unique fingerprints ( Stevens et al., 2017 ). This “SHAttered” attack required 9 quintillion SHA-1 computations, which is the equivalent to 6,500 years of single-CPU computation. The attack cost approximately $45,000 in cloud computing resources, making it accessible to well-funded adversaries but not casual attackers.