(PHP Extension) BIP39 Compute Binary Seed from Mnemonic

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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).

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

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

$crypt = new CkCrypt2();

// 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 = new CkBinData();
$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');

print 'Expected: ' . $expectedSeed . "\n";
print 'Computed: ' . $computedSeed . "\n";

// 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 = new CkBinData();
$bdSeed->AppendEncoded($computedSeed,'hex_lower');
$crypt->put_EncodingMode('hex_lower');
$crypt->put_HashAlgorithm('sha512');
$crypt->SetMacKeyString('Bitcoin seed');
$hmacSha512_hex = $crypt->macBdENC($bdSeed);

$bdHmac = new CkBinData();
$bdHmac->AppendEncoded($hmacSha512_hex,'hex_lower');

$bdXprv = new CkBinData();
$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->put_EncodingMode('hex_lower');
$crypt->put_HashAlgorithm('sha256');

$bdHash = new CkBinData();
$bdHash->AppendEncoded($crypt->hashBdENC($bdXprv),'hex_lower');
$secondHash = $crypt->hashBdENC($bdHash);
$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');

print 'Expected Master Key: ' . $expectedMasterKey . "\n";
print 'Computed Master Key: ' . $computedMasterKey . "\n";

?>