/** * To create a binary seed from the mnemonic, we use 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). * * @param mnemonic The input mnemonic which should be 128-160 bits in length containing * only valid words * @param passphrase The passphrase which will be used as part of salt for PBKDF2 * function * @return Byte array representation of the generated seed */ public static byte[] generateSeed(String mnemonic, String passphrase) { if (isMnemonicEmpty(mnemonic)) { throw new IllegalArgumentException("Mnemonic is required to generate a seed"); } passphrase = passphrase == null ? "" : passphrase; String salt = String.format("mnemonic%s", passphrase); PKCS5S2ParametersGenerator gen = new PKCS5S2ParametersGenerator(new SHA512Digest()); gen.init(mnemonic.getBytes(UTF_8), salt.getBytes(UTF_8), SEED_ITERATIONS); return ((KeyParameter) gen.generateDerivedParameters(SEED_KEY_SIZE)).getKey(); }
/** * To create a binary seed from the mnemonic, we use 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). * * @param mnemonic The input mnemonic which should be 128-160 bits in length containing * only valid words * @param passphrase The passphrase which will be used as part of salt for PBKDF2 * function * @return Byte array representation of the generated seed */ public static byte[] generateSeed(String mnemonic, String passphrase) { if (isMnemonicEmpty(mnemonic)) { throw new IllegalArgumentException("Mnemonic is required to generate a seed"); } passphrase = passphrase == null ? "" : passphrase; String salt = String.format("mnemonic%s", passphrase); PKCS5S2ParametersGenerator gen = new PKCS5S2ParametersGenerator(new SHA512Digest()); gen.init(mnemonic.getBytes(UTF_8), salt.getBytes(UTF_8), SEED_ITERATIONS); return ((KeyParameter) gen.generateDerivedParameters(SEED_KEY_SIZE)).getKey(); }