【Java密碼學】使用Bouncy Castle生成數字簽名、數字信封

Bouncy Castle（輕量級密碼術包）是一種用於 Java 平臺的開放源碼的輕量級密碼術包，它支持大量的密碼術算法，並提供 JCE 1.2.1 的實現。最近項目上正好用到了Bouncy Castle，用於生成數字簽名、數字信封，去網上找了好久，都沒有找到合適的案例，而Bouncy Castle自己的文檔也很少，最有用的就是官網上的Java Doc文檔，由於這個問題也困擾了我好幾天，最後仍是經過閱讀Java Doc文檔找到了合適的類和方法，果真閱讀Doc文檔仍是頗有必要的啊。好了，話很少說，把我寫的方法列出來，以防忘記，並給有一樣需求的同窗提供一些參考，其中有些代碼也是參考了網上的寫法，最有用的仍是Doc文檔裏提供的一些示例寫法，基本的需求已經可以知足了。

要使用Bouncy Castle，就須要引入相應的jar包，在官網就能夠根據本身的須要進行下載，而後就可使用了。

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";

    /**
     * 生成數字簽名
     * @param srcMsg 源信息
     * @param charSet 字符編碼
     * @param certPath 證書路徑
     * @param certPwd 證書密碼
     * @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做爲安全提供
            Security.addProvider(provider);

            // 加載證書
            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);

            // 獲取私鑰
            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;
        }
    }

    /**
     * 驗證數字簽名
     * @param signedData
     * @return
     */
    public boolean signedDataVerify(byte[] signedData) {
        boolean verifyRet = true;
        try {
            // 新建PKCS#7簽名數據處理對象
            CMSSignedData sign = new CMSSignedData(signedData);

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

            // 得到證書信息
            Store certs = sign.getCertificates();

            // 得到簽名者信息
            SignerInformationStore signers = sign.getSignerInfos();
            Collection c = signers.getSigners();
            Iterator it = c.iterator();

            // 當有多個簽名者信息時須要所有驗證
            while (it.hasNext()) {
                SignerInformation signer = (SignerInformation) it.next();

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

                // 驗證數字簽名
                if (signer.verify(new JcaSimpleSignerInfoVerifierBuilder()
                        .setProvider("BC").build(cert))) {
                    verifyRet = true;
                } else {
                    verifyRet = false;
                }
            }

        } catch (Exception e) {
            verifyRet = false;
            e.printStackTrace();
            System.out.println("驗證數字簽名失敗");
        }
        return verifyRet;
    }

    /**
     * 加密數據
     * @param srcMsg 源信息
     * @param certPath 證書路徑
     * @param charSet 字符編碼
     * @return
     * @throws Exception
     */
    public String envelopeMessage(String srcMsg, String certPath, String charSet) throws Exception {
        CertificateFactory certificatefactory;
        X509Certificate cert;
        // 使用公鑰對對稱密鑰進行加密 //若此處不加參數 "BC" 會報異常：CertificateException -
        certificatefactory = CertificateFactory.getInstance("X.509", "BC");
        // 讀取.crt文件；你能夠讀取絕對路徑文件下的crt，返回一個InputStream（或其子類）便可。
        InputStream bais = new FileInputStream(certPath);

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

        //添加數字信封
        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;
    }

    /**
     * 解密數據
     * @param encode 加密後的密文
     * @param certPath 證書路徑
     * @param certPwd 證書密碼
     * @param charSet 字符編碼
     * @return
     * @throws Exception
     */
    public String openEnvelope(String encode, String certPath, String certPwd, String charSet) throws Exception {
        //獲取密文
        CMSEnvelopedData ed = new CMSEnvelopedData(Base64.decode(encode.getBytes()));

        RecipientInformationStore recipients = ed.getRecipientInfos();

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

        // 加載證書
        KeyStore ks = KeyStore.getInstance(ksType);
        ks.load(new FileInputStream(certPath), certPwd.toCharArray());
        
        String priKeyName = null;
        if (ks.aliases().hasMoreElements()) {
            priKeyName = ks.aliases().nextElement();
        }
        
        // 獲取私鑰
        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());
    }


}