.pfx证书 .cer证书MD5withRSA加密

public static String sign(String pfxFile, String pfxPwd, String str, String signature, String coding) {
    try {
        //获取pfx文件的prikey
        Security.addProvider(new BouncyCastleProvider());
        KeyStore e = KeyStore.getInstance("PKCS12", "BC");
        FileInputStream fis = new FileInputStream(pfxFile);
        e.load(fis, pfxPwd.toCharArray());
        Enumeration aliases = e.aliases();
        String keyAlias = null;
        PrivateKey priKey = null;
        if (aliases != null) {
            while (aliases.hasMoreElements()) {
                keyAlias = (String) aliases.nextElement();
                priKey = (PrivateKey) e.getKey(keyAlias, pfxPwd.toCharArray());
                if (priKey != null) {
                    break;
                }
            }
        }
        //使用Signature加密
        Signature signet = Signature.getInstance(signature);
        signet.initSign(priKey);
        signet.update(str.getBytes(coding));
        byte[] signed = signet.sign();
        String strSign = new String(Base64.encode(signed));
        return strSign;
    } catch (Exception ex) {
        System.out.println(ex);
    }
    return null;
}

System.out.println(sign("C://xxx.pfx","123456","123","MD5withRSA","UTF-8"));

//通过cer文件获取到publickey
String e ="c://xxx.cer";
logger.debug("公钥证书路径：" + e);
FileInputStream in = new FileInputStream(e);
CertificateFactory cf = CertificateFactory.getInstance("X.509");
Certificate cac = cf.generateCertificate(in);
PublicKey pubKey = cac.getPublicKey();
in.close();

//通过pubkey加密
Signature signetcheck = Signature.getInstance("MD5withRSA");
signetcheck.initVerify(pubKey);
signetcheck.update(Base64.decode(msg));

//验证是否一样
if (!signetcheck.verify(Base64.decode(check))) {
    throw new  异常("Verify Signature Error");
}