【Java密码学】使用Bouncy Castle生成数字签名、数字信封

Bouncy Castle（轻量级密码术包）是一种用于 Java 平台的开放源码的轻量级密码术包，它支持大量的密码术算法，并提供 JCE 1.2.1 的实现。最近项目上正好用到了Bouncy Castle，用于生成数字签名、数字信封，去网上找了很久，都没有找到合适的案例，而Bouncy Castle本身的文档也不多，最有用的就是官网上的Java Doc文档，因为这个问题也困扰了我好几天，最后还是通过阅读Java Doc文档找到了合适的类和方法，果然阅读Doc文档还是很有必要的啊。好了，话不多说，把我写的方法列出来，以防忘记，并给有同样需求的同学提供一些参考，其中有些代码也是参考了网上的写法，最有用的还是Doc文档里提供的一些示例写法，基本的需求已经能够满足了。

要使用Bouncy Castle，就需要引入相应的jar包，在官网就可以根据自己的需要进行下载，然后就可以使用了。

import java.io.FileInputStream;
import java.io.InputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.Provider;
import java.security.Security;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.cert.X509CertificateHolder;
import org.bouncycastle.cert.jcajce.JcaCertStore;
import org.bouncycastle.cms.CMSEnvelopedData;
import org.bouncycastle.cms.CMSEnvelopedDataGenerator;
import org.bouncycastle.cms.CMSProcessableByteArray;
import org.bouncycastle.cms.CMSSignedData;
import org.bouncycastle.cms.CMSSignedDataGenerator;
import org.bouncycastle.cms.CMSTypedData;
import org.bouncycastle.cms.RecipientInformation;
import org.bouncycastle.cms.RecipientInformationStore;
import org.bouncycastle.cms.SignerInformation;
import org.bouncycastle.cms.SignerInformationStore;
import org.bouncycastle.cms.jcajce.JcaSignerInfoGeneratorBuilder;
import org.bouncycastle.cms.jcajce.JcaSimpleSignerInfoVerifierBuilder;
import org.bouncycastle.cms.jcajce.JceCMSContentEncryptorBuilder;
import org.bouncycastle.cms.jcajce.JceKeyTransEnvelopedRecipient;
import org.bouncycastle.cms.jcajce.JceKeyTransRecipientInfoGenerator;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.operator.ContentSigner;
import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder;
import org.bouncycastle.operator.jcajce.JcaDigestCalculatorProviderBuilder;
import org.bouncycastle.util.Store;
import org.bouncycastle.util.encoders.Base64;

public class MessageUtil {
    private String ksType = "PKCS12";

    /**
     * 生成数字签名
     * @param srcMsg 源信息
     * @param charSet 字符编码
     * @param certPath 证书路径
     * @param certPwd 证书密码
     * @return
     */
    public byte[] signMessage(String srcMsg, String charSet, String certPath, String certPwd) {
        String priKeyName = null;
        char passphrase[] = certPwd.toCharArray();

        try {
            Provider provider = new BouncyCastleProvider();
            // 添加BouncyCastle作为安全提供
            Security.addProvider(provider);

            // 加载证书
            KeyStore ks = KeyStore.getInstance(ksType);
            ks.load(new FileInputStream(certPath), passphrase);

            if (ks.aliases().hasMoreElements()) {
                priKeyName = ks.aliases().nextElement();
            }
            
            Certificate cert = (Certificate) ks.getCertificate(priKeyName);

            // 获取私钥
            PrivateKey prikey = (PrivateKey) ks.getKey(priKeyName, passphrase);

            X509Certificate cerx509 = (X509Certificate) cert;

            List<Certificate> certList = new ArrayList<Certificate>();
            certList.add(cerx509);

            CMSTypedData msg = (CMSTypedData) new CMSProcessableByteArray(
                    srcMsg.getBytes(charSet));

            Store certs = new JcaCertStore(certList);

            CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
            ContentSigner sha1Signer = new JcaContentSignerBuilder(
                    "SHA1withRSA").setProvider("BC").build(prikey);

            gen.addSignerInfoGenerator(new JcaSignerInfoGeneratorBuilder(
                    new JcaDigestCalculatorProviderBuilder().setProvider("BC")
                            .build()).build(sha1Signer, cerx509));

            gen.addCertificates(certs);

            CMSSignedData sigData = gen.generate(msg, true);

            return Base64.encode(sigData.getEncoded());

        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 验证数字签名
     * @param signedData
     * @return
     */
    public boolean signedDataVerify(byte[] signedData) {
        boolean verifyRet = true;
        try {
            // 新建PKCS#7签名数据处理对象
            CMSSignedData sign = new CMSSignedData(signedData);

            // 添加BouncyCastle作为安全提供
            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());

            // 获得证书信息
            Store certs = sign.getCertificates();

            // 获得签名者信息
            SignerInformationStore signers = sign.getSignerInfos();
            Collection c = signers.getSigners();
            Iterator it = c.iterator();

            // 当有多个签名者信息时需要全部验证
            while (it.hasNext()) {
                SignerInformation signer = (SignerInformation) it.next();

                // 证书链
                Collection certCollection = certs.getMatches(signer.getSID());
                Iterator certIt = certCollection.iterator();
                X509CertificateHolder cert = (X509CertificateHolder) certIt
                        .next();

                // 验证数字签名
                if (signer.verify(new JcaSimpleSignerInfoVerifierBuilder()
                        .setProvider("BC").build(cert))) {
                    verifyRet = true;
                } else {
                    verifyRet = false;
                }
            }

        } catch (Exception e) {
            verifyRet = false;
            e.printStackTrace();
            System.out.println("验证数字签名失败");
        }
        return verifyRet;
    }

    /**
     * 加密数据
     * @param srcMsg 源信息
     * @param certPath 证书路径
     * @param charSet 字符编码
     * @return
     * @throws Exception
     */
    public String envelopeMessage(String srcMsg, String certPath, String charSet) throws Exception {
        CertificateFactory certificatefactory;
        X509Certificate cert;
        // 使用公钥对对称密钥进行加密 //若此处不加参数 "BC" 会报异常：CertificateException -
        certificatefactory = CertificateFactory.getInstance("X.509", "BC");
        // 读取.crt文件；你可以读取绝对路径文件下的crt，返回一个InputStream（或其子类）即可。
        InputStream bais = new FileInputStream(certPath);

        cert = (X509Certificate) certificatefactory.generateCertificate(bais);

        //添加数字信封
        CMSTypedData msg = new CMSProcessableByteArray(srcMsg.getBytes(charSet));

        CMSEnvelopedDataGenerator edGen = new CMSEnvelopedDataGenerator();

        edGen.addRecipientInfoGenerator(new JceKeyTransRecipientInfoGenerator(
                cert).setProvider("BC"));

        CMSEnvelopedData ed = edGen.generate(msg,
                new JceCMSContentEncryptorBuilder(PKCSObjectIdentifiers.rc4)
                        .setProvider("BC").build());

        String rslt = new String(Base64.encode(ed.getEncoded()));

        System.out.println(rslt);
        return rslt;
    }

    /**
     * 解密数据
     * @param encode 加密后的密文
     * @param certPath 证书路径
     * @param certPwd 证书密码
     * @param charSet 字符编码
     * @return
     * @throws Exception
     */
    public String openEnvelope(String encode, String certPath, String certPwd, String charSet) throws Exception {
        //获取密文
        CMSEnvelopedData ed = new CMSEnvelopedData(Base64.decode(encode.getBytes()));

        RecipientInformationStore recipients = ed.getRecipientInfos();

        Collection c = recipients.getRecipients();
        Iterator it = c.iterator();

        // 加载证书
        KeyStore ks = KeyStore.getInstance(ksType);
        ks.load(new FileInputStream(certPath), certPwd.toCharArray());
        
        String priKeyName = null;
        if (ks.aliases().hasMoreElements()) {
            priKeyName = ks.aliases().nextElement();
        }
        
        // 获取私钥
        PrivateKey prikey = (PrivateKey) ks.getKey(priKeyName, certPwd.toCharArray());

        byte[] recData = null;
        //解密
        if (it.hasNext()) {
            RecipientInformation recipient = (RecipientInformation) it.next();

            recData = recipient.getContent(new JceKeyTransEnvelopedRecipient(
                    prikey).setProvider("BC"));
        }

        return new String(recData, charSet);
    }

    public MessageUtil() {
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    }


}