fci4096

A BIP39-inspired mnemonic implementation using 4096 Chinese four-character idioms as the wordlist.

Overview

fci4096 is a mnemonic system inspired by BIP39, replacing the English word list with 4096 standard four-character Chinese idioms. Each idiom encodes 12 bits of information (2^12 = 4096), providing higher information density compared to BIP39's 2048-word list (11 bits/word) for the same number of words.

Differences from BIP39

Encoding Scheme

With a 4096-word list, each idiom encodes 12 bits. The checksum is 1/8 of the entropy length:

The checksum is the leading N bits of SHA-256(entropy).

Installation

[dependencies]
fci4096 = "0.1"

Feature Flags

Usage

Generate a Mnemonic

use fci4096::{generate, IdiomMnemonicSize};

let mnemonic = generate(IdiomMnemonicSize::Idioms12)?;
println!("{}", mnemonic.phrase());
// e.g. 哀而不伤 按部就班 草木皆兵 ...

From Entropy

use fci4096::from_entropy;

let entropy = [0x00u8; 16]; // 128 bits of entropy
let mnemonic = from_entropy(&entropy)?;

Parse and Validate

use fci4096::{from_phrase, validate};

let phrase = "哀而不伤 按部就班 草木皆兵 ...";
if validate(phrase) {
    let mnemonic = from_phrase(phrase)?;
    let entropy = mnemonic.to_entropy()?;
}

Generate a Seed

let seed = mnemonic.to_seed("passphrase");
// Returns [u8; 64], using PBKDF2-SHA512 with 4096 iterations

CLI Examples

# Generate a 12-word mnemonic
cargo run --example generate 12

# Recover the seed
cargo run --example recover "idiom1 idiom2 idiom3 ..." [passphrase]

Security

• Entropy source: Uses the getrandom crate for OS-level cryptographically secure random numbers
• Checksum: 128-bit entropy with 16-bit checksum (BIP39 uses only 4 bits), providing stronger error detection
• Seed derivation: PBKDF2-SHA512, 4096 iterations, passphrase is NFKD-normalized
• Wordlist: 4096 standard four-character idioms, sorted by pinyin, systematically reviewed to remove derogatory idioms

License

MIT