From a2592156207ed04671d6532cec4997fb1dab1595 Mon Sep 17 00:00:00 2001 From: Bitflash Date: Tue, 4 Aug 2026 10:19:38 -0300 Subject: docs: one documentation directory, not two (#137) docs/ has held the README's images since the fair-launch release. I added doc/ yesterday for the derivation spec without looking, and #108 then correctly used docs/ -- leaving the repository with both, one letter apart, which is the kind of thing that quietly costs someone ten minutes a year forever. The mistake was mine, so the move is mine: derivation.md and verify-derivation.py go to docs/, and the two README links follow. No content changes. The verifier still reproduces the wallet from its new path, which is the only thing here that can actually break. --- doc/derivation.md | 125 ------------------------------------------------------ 1 file changed, 125 deletions(-) delete mode 100644 doc/derivation.md (limited to 'doc/derivation.md') diff --git a/doc/derivation.md b/doc/derivation.md deleted file mode 100644 index 3ca8339..0000000 --- a/doc/derivation.md +++ /dev/null @@ -1,125 +0,0 @@ -# Key derivation and address format - -This document exists so that a Bitflash wallet can be rebuilt **without this -software**. If the project stops, the binaries are lost, or you simply do not -trust them, the twelve words plus what is written here are enough to recover -your private keys with ordinary cryptographic tools. - -Everything below is verified by `doc/verify-derivation.py`, a self-contained -script that implements this document from scratch — no Bitflash code, no -libraries beyond Python's standard library — and checks that it reproduces the -addresses the wallet produces. If the two ever disagree, this document is wrong -and the script will say so. - -## Addresses - -An address is the Base58Check encoding of a version byte followed by -`RIPEMD160(SHA256(public key))`. - -| | | -|---|---| -| curve | secp256k1 | -| public key encoding | **uncompressed**, 65 bytes, `0x04 ‖ X ‖ Y` | -| address version byte | **25** (`0x19`), which is why addresses begin with `B` | -| checksum | first 4 bytes of `SHA256(SHA256(payload))`, appended before Base58 | - -The public key is uncompressed. This matters more than anything else here: the -same private key hashed in compressed form gives a completely different, valid -looking address that holds nothing. Bitflash descends from Bitcoin 0.1.0, which -predates compressed keys. - -Outputs paying an address use the usual script: - -``` -OP_DUP OP_HASH160 OP_EQUALVERIFY OP_CHECKSIG -``` - -Mined coins and payments made directly to a public key use the older form -` OP_CHECKSIG`. A wallet scanning the chain must recognise both. - -## From twelve words to a master key - -Standard BIP-39 and BIP-32, with no modifications: - -1. **Seed.** `PBKDF2-HMAC-SHA512(password = mnemonic, salt = "mnemonic" + passphrase, iterations = 2048, length = 64 bytes)`. Bitflash always uses an empty passphrase, so the salt is the literal string `mnemonic`. -2. **Master key.** `I = HMAC-SHA512(key = "Bitcoin seed", data = seed)`. The master private key is `I[0..32]`, the master chain code is `I[32..64]`. - -Child derivation is BIP-32 `CKDpriv`, hardened and non-hardened as usual. - -## Two layouts - -A wallet records which layout it uses in `wallet.dat` under the key `hdschema`. -Wallets created before that field existed are treated as legacy. - -### Legacy (`hdschema` absent or 1) - -``` -m/i' -``` - -Hardened children of the master key, one flat sequence. Index 0 is the wallet's -default receiving address; the key pool and change take the following indices. - -Used by every wallet created before BIP-44 support existed, and kept forever: -those phrases must keep working. - -### BIP-44 (`hdschema` = 2) - -``` -m/44'/4346950'/0'/0/i external chain (receiving) -m/44'/4346950'/0'/1/i internal chain (change) -``` - -Coin type **4346950** is `0x425446`, the ASCII bytes `BTF`. It is -[registered for Bitflash under the symbol BITFLASH](https://github.com/satoshilabs/slips/blob/master/slip-0044.md). -The account level is fixed at `0'`; Bitflash does not expose multiple accounts. - -A wallet restored from a phrase scans **both** layouts, because the words alone -do not say which one produced them. - -## Test vectors - -Using the public BIP-39 test mnemonic: - -``` -abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about -``` - -### Legacy - -| path | address | -|---|---| -| `m/0'` | `BHJNmVvkVv59fgn7gmgP78BtciQi2HY8Hy` | -| `m/1'` | `B5qh9opG8sH8Mv9k2xzHoTeSUd9BkT6XEZ` | -| `m/2'` | `BCNH8uGyvkiz3uXjhA9iiF27PWAaTStNin` | -| `m/3'` | `BC1QNaXuTPGDgLZy53PghZMHEmZcp5GLgD` | - -### BIP-44 external chain - -| path | address | -|---|---| -| `m/44'/4346950'/0'/0/0` | `BF1ukigB1afmqxH64gJymPwUqFBrRqWbrb` | -| `m/44'/4346950'/0'/0/1` | `BACY8pcuCapNQr897eRHroNrgN38GSsEzV` | -| `m/44'/4346950'/0'/0/2` | `BMzkMN2k1phNBqy8RPb4Pv1i2QpwsWkKPa` | -| `m/44'/4346950'/0'/0/3` | `BNPZ8U6FHXr9Ererk8psyM2RqEVtF6sfBQ` | - -Check them yourself: - -``` -python doc/verify-derivation.py -``` - -Both tables were produced by the wallet — the legacy one by the v1.2.15 binary, -which only knows that layout — and then reproduced independently by the script. - -## What this document does not give you - -Deriving the keys is not the same as spending. To move recovered coins you still -need a node that knows the network: the chain, the peer protocol, and the -transaction format. This document is about **not losing the keys**, which is the -part that cannot be reconstructed later by reading source code that no longer -exists anywhere. - -Note also that `wallet.dat` stores private keys unencrypted. A recovery phrase -protects you against losing the file; it does not protect the file. Anyone who -can read it can spend the coins. -- cgit v1.2.3