Crypto Wallet C

Version: 0.1.0

A minimal implementation of BIPs 32, 39, and 44 in C — generate Bitcoin wallets from mnemonics, derive keys, and manage seeds with no heavy libraries.

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Summary

• About
• Features
• Folder Structure
• Usage
• Build Instructions
• License

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About

The code is built entirely with basic C libraries, avoiding external dependencies wherever possible. It demonstrates the full process of wallet creation — from random entropy to mnemonic, seed, private key, and public key derivation.

Features

• BIP-39 mnemonic generation
• BIP-32 HD Wallet key derivation
• BIP-44 multi-account path support
• Minimal SHA-256 and PBKDF2 implementation
• Works only with basic C libraries

Folder Structure

btc-wallet-c/ ├── src/ # C source files │ ├── main.c # Program entry point │ ├── sha256.c # SHA-256 mini implementation │ ├── pbkdf2.c # PBKDF2-HMAC-SHA512 (seed generation) │ ├── bip39.c # Mnemonic generation and handling │ ├── bip32.c # HD Wallet (key derivation) │ └── utils.c # Randomness, base conversions, helpers │ ├── include/ # Header files │ ├── sha256.h │ ├── pbkdf2.h │ ├── bip39.h │ ├── bip32.h │ └── utils.h │ ├── wordlist/ # English BIP-39 wordlist file │ └── english.txt │ ├── build/ # Compiled binaries (gitignore this folder) │ ├── README.md # Project overview ├── LICENSE # MIT license (recommended) ├── Makefile # Simple build automation (optional but pro) └── .gitignore # Ignore build artifacts

📦 Short explanation of folders:

src/ → all your .c implementation files.

include/ → all your .h header files.

wordlist/ → the 2048 BIP-39 words (english.txt).

build/ → where your compiled crypto-wallet-c binary goes.

Top level → README, license, makefile, and config files.

Build

make

Usage

./crypto-wallet-c 128   # 128 bits entropy (12 words)
./crypto-wallet-c 256   # 256 bits entropy (24 words)

🔥 Most direct comparison:

• 128 bits (12 words)

  • It is already very secure.
  • Attacking a key is practically impossible today.
  • Easier to write down/memorize.
  • Widely used in wallets such as Electrum, Ledger, Trezor.

• 256 bits (24 words)

  • Absurd security (it is “overkill” today).
  • Takes much longer to generate and process.
  • Harder to write down (more chance of error).
  • Requires more patience from the user.

Relation between Entropy and Number of Words (BIP-39)

Entropy (bits)	Checksum (bits)	Total bits	Number of words
128	4	132	12
160	5	165	15
192	6	198	18
224	7	231	21
256	8	264	24

Formulas used

• checksum_bits = entropy_bits / 32
• total_bits = entropy_bits + checksum_bits
• words = total_bits / 11

Quick summary

• 128 bits → 12 words
• 160 bits → 15 words
• 192 bits → 18 words
• 224 bits → 21 words
• 256 bits → 24 words

Project Goals

Learn and demonstrate how Bitcoin key derivation works at the byte level Create a minimalistic implementation without external cryptographic libraries Help others understand BIP-32, BIP-39, and BIP-44 through readable C code

Roadmap

✅ Entropy generation and checksum

✅ Mnemonic creation from wordlist

🔳 Seed derivation with PBKDF2-HMAC-SHA512

🔳 Full master key + chain code generation (BIP-32)

🔳 Child key derivation (hardened and non-hardened)

🔳 Wallet paths (m/44'/0'/0'/0/0) (BIP-44)

🔳 Address generation (P2PKH / P2WPKH)

BIPs

BIP	Nome	O que implementamos?
BIP-39	Mnemonic code for generating deterministic keys	✅ Geramos a mnemônica a partir de entropia + checksum + wordlist
BIP-32	Hierarchical Deterministic Wallets	⚠️ Em andamento (derivar chave privada da seed)
BIP-44	Multi-account hierarchy for deterministic wallets	❌ Ainda não implementado

License

MIT License.