普通私鑰32B,版本號以"00"開頭
WIF（Wallet Import Format）格式私鑰51位，以“5”開頭，版本號以"80"開頭
wif壓縮格式52位，以“L"/"K"開頭，最后一位為是否壓縮
wif格式可以自動偵測地址錯誤，通過私鑰的hash值產生校驗碼

package crypto;

public class BitcoinAddressUtil {
    /**
     * 將16進制私鑰轉成WIF格式或WIF-compressed格式
     * flag:boolean,是否采用壓縮格式.true:壓縮格式
     */
    public static String generatePrivateKeyWIF(String hexprivKey, boolean flag) {
        String versionStr = "";
        if (flag) {
            versionStr = "80" + hexprivKey + "01";
        } else {
            versionStr = "80" + hexprivKey;
        }
        try {
            String hashDouble = HashUtils.sha256(HashUtils.hexToByteArray(HashUtils.sha256(HashUtils.hexToByteArray(versionStr))));
            String checkSum = hashDouble.substring(0, 8);

            String strPrivKey = versionStr + checkSum;
            return Base58Util.encode(HashUtils.hexToByteArray(strPrivKey));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * WIF格式私鑰返回到16進制格式
     *
     * @param wifPrivKey ,WIF格式私鑰
     */
    public static String getHexPrivateKey(String wifPrivKey) {
        validateWifPrivateKey(wifPrivKey);
        boolean flag = true;
        if (wifPrivKey.length() == 51 && wifPrivKey.indexOf("5") == 0) {
            flag = false;
        }
        byte[] arrPrivKey = Base58Util.decode(wifPrivKey);
        String hexStr = HashUtils.byte2HexStr(arrPrivKey);
        String result = "";
        if (flag) {
            result = hexStr.substring(2, hexStr.length() - 10);
        } else {
            result = hexStr.substring(2, hexStr.length() - 8);
        }
        return result;
    }

    //驗證wif私鑰是否有效
    public static boolean validateWifPrivateKey(String wifPrivateKey) {
        byte[] arrPrivateKey = Base58Util.decode(wifPrivateKey);
        String hexStr = HashUtils.bytesToHex(arrPrivateKey);
        String checksum = hexStr.substring(hexStr.length() - 8);
        String versionStr = hexStr.substring(0, hexStr.length() - 8);
        try {
            String checksumNew = HashUtils.sha256(HashUtils.hexToByteArray(HashUtils.sha256(HashUtils.hexToByteArray(versionStr)))).substring(0, 8);
            if (checksum.equals(checksumNew)) {
                return true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    public static void main(String[] args) {
        String ss = generatePrivateKeyWIF("18E14A7B6A307F426A94F8114701E7C8E774E7F9A47E2C2035DB29A206321725", false);
        System.out.println(ss);
        String hexPrivateKey = getHexPrivateKey("Kx45GeUBSMPReYQwgXiKhG9FzNXrnCeutJp4yjTd5kKxCitadm3C");
        System.out.println(hexPrivateKey);
        boolean flag = validateWifPrivateKey("5J1F7GHadZG3sCCKHCwg8Jvys9xUbFsjLnGec4H125Ny1V9nR6V");
        System.out.println(flag);
    }
}