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4 articles with this tag.
SSH secures remote logins with a binary packet protocol, a curve25519-sha256 key exchange, and an Ed25519 host key. Learn the handshake and the chacha20-poly1305@openssh.com cipher, with Python code that reproduces the IETF draft's own worked example byte for byte.
29 min read
WireGuard is a VPN protocol built on the Noise IKpsk2 handshake. Learn the two handshake messages, the cookie mechanism against denial of service, the replay window, and the timers, with Python code that reproduces an official test vector and the Linux kernel self-test.
37 min read
Ed25519 is the EdDSA signature scheme on the Edwards curve of Curve25519, defined in RFC 8032. Learn how a 32-byte seed becomes a key, how a deterministic nonce replaces random numbers, how a signature is checked with the cofactor, and why the range check on S matters.
19 min read
X25519 is the Diffie-Hellman function on Curve25519, defined in RFC 7748. Learn how a 32-byte private key is clamped, how the Montgomery ladder multiplies a point using only its u coordinate, why the curve was chosen, and what the all-zero check protects against.
18 min read
