Delphi ActiveX

BIP39 Compute Binary Seed from Mnemonic

See more Encryption Examples

Creates a binary seed from a mnemonic. Uses the PBKDF2 function with a mnemonic sentence (in UTF-8 NFKD) used as the password and the string "mnemonic" + passphrase (again in UTF-8 NFKD) used as the salt. The iteration count is set to 2048 and HMAC-SHA512 is used as the pseudo-random function. The length of the derived key is 512 bits (= 64 bytes). Delphi ActiveX

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
crypt: TChilkatCrypt2;
mnemonic: WideString;
passphrase: WideString;
expectedSeed: WideString;
expectedMasterKey: WideString;
bdSalt: TChilkatBinData;
computedSeed: WideString;
bdSeed: TChilkatBinData;
hmacSha512_hex: WideString;
bdHmac: TChilkatBinData;
bdXprv: TChilkatBinData;
bdHash: TChilkatBinData;
secondHash: WideString;
computedMasterKey: WideString;

begin
// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

crypt := TChilkatCrypt2.Create(Self);

// Test with the test vectors at https://github.com/trezor/python-mnemonic/blob/master/vectors.json

// This is the 2nd test vector..
mnemonic := 'legal winner thank year wave sausage worth useful legal winner thank yellow';
passphrase := 'TREZOR';
expectedSeed := '2e8905819b8723fe2c1d161860e5ee1830318dbf49a83bd451cfb8440c28bd6fa457fe1296106559a3c80937a1c1069be3a3a5bd381ee6260e8d9739fce1f607';
expectedMasterKey := 'xprv9s21ZrQH143K2gA81bYFHqU68xz1cX2APaSq5tt6MFSLeXnCKV1RVUJt9FWNTbrrryem4ZckN8k4Ls1H6nwdvDTvnV7zEXs2HgPezuVccsq';

// The mnemonic sentence (in UTF-8 NFKD) used as the password.
// The string "mnemonic" + passphrase (again in UTF-8 NFKD) used as the salt.
// The iteration count is set to 2048 and HMAC-SHA512 is used as the pseudo-random function.
// The length of the derived key is 512 bits (= 64 bytes). 

// We want the computed seed to be lowercase hex, therefore our salt must also be hex.
// The seed is the keyword "mnemonic" + passphrase (in this case is "TREZOR") converted to hex.
bdSalt := TChilkatBinData.Create(Self);
bdSalt.AppendString('mnemonic','utf-8');
bdSalt.AppendString(passphrase,'utf-8');

computedSeed := crypt.Pbkdf2(mnemonic,'utf-8','sha512',bdSalt.GetEncoded('hex_lower'),2048,512,'hex_lower');

Memo1.Lines.Add('Expected: ' + expectedSeed);
Memo1.Lines.Add('Computed: ' + computedSeed);

// To compute the hd_master_key, duplicate this Python code:

//     def to_hd_master_key(seed: bytes, testnet: bool = False) -> str:
//         if len(seed) != 64:
//             raise ValueError("Provided seed should have length of 64")
// 
//         # Compute HMAC-SHA512 of seed
//         seed = hmac.new(b"Bitcoin seed", seed, digestmod=hashlib.sha512).digest()
// 
//         # Serialization format can be found at: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#Serialization_format
//         xprv = b"\x04\x88\xad\xe4"  # Version for private mainnet
//         if testnet:
//             xprv = b"\x04\x35\x83\x94"  # Version for private testnet
//         xprv += b"\x00" * 9  # Depth, parent fingerprint, and child number
//         xprv += seed[32:]  # Chain code
//         xprv += b"\x00" + seed[:32]  # Master key
// 
//         # Double hash using SHA256
//         hashed_xprv = hashlib.sha256(xprv).digest()
//         hashed_xprv = hashlib.sha256(hashed_xprv).digest()
// 
//         # Append 4 bytes of checksum
//         xprv += hashed_xprv[:4]
// 
//         # Return base58
//         return b58encode(xprv)

// First compute the HMAC-SHA512 of the computedSeed
bdSeed := TChilkatBinData.Create(Self);
bdSeed.AppendEncoded(computedSeed,'hex_lower');
crypt.EncodingMode := 'hex_lower';
crypt.HashAlgorithm := 'sha512';
crypt.SetMacKeyString('Bitcoin seed');
hmacSha512_hex := crypt.MacBdENC(bdSeed.ControlInterface);

bdHmac := TChilkatBinData.Create(Self);
bdHmac.AppendEncoded(hmacSha512_hex,'hex_lower');

bdXprv := TChilkatBinData.Create(Self);
bdXprv.AppendEncoded('0488ade4','hex_lower');
bdXprv.AppendEncoded('000000000000000000','hex_lower');
bdXprv.AppendEncoded(bdHmac.GetEncodedChunk(32,32,'hex_lower'),'hex_lower');
bdXprv.AppendByte(0);
bdXprv.AppendEncoded(bdHmac.GetEncodedChunk(0,32,'hex_lower'),'hex_lower');

// Double hash using SHA256
crypt.EncodingMode := 'hex_lower';
crypt.HashAlgorithm := 'sha256';

bdHash := TChilkatBinData.Create(Self);
bdHash.AppendEncoded(crypt.HashBdENC(bdXprv.ControlInterface),'hex_lower');
secondHash := crypt.HashBdENC(bdHash.ControlInterface);
bdHash.Clear();
bdHash.AppendEncoded(secondHash,'hex_lower');

// Append the 1st 4 bytes of the bdHash to bdXprv.
bdXprv.AppendEncoded(bdHash.GetEncodedChunk(0,4,'hex_lower'),'hex_lower');

// Base58 encode bdXprv
computedMasterKey := bdXprv.GetEncoded('base58');

Memo1.Lines.Add('Expected Master Key: ' + expectedMasterKey);
Memo1.Lines.Add('Computed Master Key: ' + computedMasterKey);
end;