var passphraseBits = sjcl.codec.utf8String.toBits(passphrase);
var result = sjcl.misc.pbkdf2(mnemonicBits, passphraseBits, PBKDF2_ROUNDS, 512, hmacSHA512);
var hashHex = sjcl.codec.hex.fromBits(result);
var passphraseBits = sjcl.codec.utf8String.toBits(passphrase);
var result = sjcl.misc.pbkdf2(mnemonicBits, passphraseBits, PBKDF2_ROUNDS, 512, hmacSHA512);
var hashHex = sjcl.codec.hex.fromBits(result);