Cryptography with intuition
Begin with “Hashes: fingerprints for data” and work toward “Signature verification practice set”. Each available lesson includes a visual explanation and a quick knowledge check.
Read in order or choose a topic below. Completion marks stay in this browser. All 20 lessons in this track are available.
- 01
Hashes: fingerprints for data
The same input gives the same fingerprint; a tiny edit changes it.
6 MIN READ - 02
Signatures and permissions
Prove authorization without sharing the secret that creates it.
7 MIN READ - 03
Bytes versus hexadecimal display
Hex text is a way to write bytes, not automatically the bytes themselves.
4 MIN READ - 04
Keccak-256 versus SHA3-256
Similar names do not make two digest algorithms interchangeable.
4 MIN READ - 05
Hash preimages and collisions
Finding an input for a digest differs from finding two matching digests.
4 MIN READ - 06
Domain separation explained
Bind a digest to the intended protocol context.
4 MIN READ - 07
Elliptic curve intuition
A public key is derived through a one-way group operation.
4 MIN READ - 08
secp256k1 keys at a glance
Ethereum EOA signing uses a specific curve and valid scalar range.
4 MIN READ - 09
Ethereum address derivation
An EOA address is derived from a public key, not directly from its display text.
4 MIN READ - 10
Signature r, s and v fields
Signature components need a stated encoding and signing context.
4 MIN READ - 11
Recovering an externally owned signer
Recovery identifies a candidate signer for one digest and signature.
4 MIN READ - 12
Personal message signing prefixes
Personal-message hashing prefixes the exact message length and bytes.
4 MIN READ - 13
EIP-712 domain separators
Typed signing binds structured content to a specified domain.
4 MIN READ - 14
EIP-712 typed structs
Type definitions participate in the signed digest.
4 MIN READ - 15
Nonces and replay protection
A valid authorization may need to be usable only once.
4 MIN READ - 16
Deadlines and signature expiry
Expiry is enforced by verification logic, not by the bytes aging automatically.
4 MIN READ - 17
ERC-1271 contract signatures
A contract account can validate signatures under its own policy.
4 MIN READ - 18
Malleability and signature normalization
Different signature encodings can relate to the same authorization.
4 MIN READ - 19
Commit and reveal patterns
Commit to a choice before exposing the choice and salt.
4 MIN READ - 20
Signature verification practice set
Check digest construction, account policy and replay rules together.
4 MIN READ