Ledger_BitBox02.md

Ledger/BitBox02 key format

• Deprecated: no
• Summary: Used by Ledger hardware wallets

Reference implementation by Ledger: HDEd25519.py

Implementation by BitBox02: keystore.c

Note: Ledger and BitBox02 also allow users to set an additional passphrase

Code

function generateMasterKey(seed, password) {
    let data = PBKDF2
        ( kdf=HMAC-SHA512
        , iter=2048
        , salt="mnemonic" + UTF8NFKD(password)
        , password=UTF8NFKD(spaceSeparated(toMnemonic(seed)))
        , outputLen=64
        );

    let cc = HMAC
        ( hash=SHA256
        , key="ed25519 seed"
        , message=UTF8NFKD(1) + data
        );

    let (iL, iR) = hashRepeatedly(data);

    return (tweakBits(iL) + iR + cc);
}

function hashRepeatedly(message) {
    let (iL, iR) = HMAC
        ( hash=SHA512
        , key="ed25519 seed"
        , message=message
        );

    if (iL[31] & 0b0010_0000) {
        return hashRepeatedly(iL + iR);
    }

    return (iL, iR);
}

function tweakBits(data) {
    // * clear the lowest 3 bits
    // * clear the highest bit
    // * set the highest 2nd bit
    data[0]  &= 0b1111_1000;
    data[31] &= 0b0111_1111;
    data[31] |= 0b0100_0000;

    return data;
}

Test vectors

No passphrase no iterations

recovery phrase

recall grace sport punch exhibit mad harbor stand obey short width stem awkward used stairs wool ugly trap season stove worth toward congress jaguar

master key

a08cf85b564ecf3b947d8d4321fb96d70ee7bb760877e371899b14e2ccf88658104b884682b57efd97decbb318a45c05a527b9cc5c2f64f7352935a049ceea60680d52308194ccef2a18e6812b452a5815fbd7f5babc083856919aaf668fe7e4

---

No passphrase with iterations

recovery phrase

correct cherry mammal bubble want mandate polar hazard crater better craft exotic choice fun tourist census gap lottery neglect address glow carry old business

master key

587c6774357ecbf840d4db6404ff7af016dace0400769751ad2abfc77b9a3844cc71702520ef1a4d1b68b91187787a9b8faab0a9bb6b160de541b6ee62469901fc0beda0975fe4763beabd83b7051a5fd5cbce5b88e82c4bbaca265014e524bd

---

With passphrase

recovery phrase

abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon art

passphrase

foo (as utf8 bytes)

master key

f053a1e752de5c26197b60f032a4809f08bb3e5d90484fe42024be31efcba7578d914d3ff992e21652fee6a4d99f6091006938fac2c0c0f9d2de0ba64b754e92a4f3723f23472077aa4cd4dd8a8a175dba07ea1852dad1cf268c61a2679c3890