Cryptography is not Magic (or Why You should Never Roll your own Crypto)

Cryptography has learnable rules rather than being dark magic, and the piece argues that people should be pointed to those rules instead of being told never to build their own crypto. Implementing primitives mainly requires avoiding timing side channels through constant-time code and checking correctness against reference implementations or test vectors. Designing protocols requires defining a threat model and proving security against it, such as IND-CCA2 for untrusted networks or IND-CPA for passive adversaries. Its stated basis is a programmer working since 2007 who wrote a crypto library whose recent audit found no major flaw.