import org.spongycastle.cert.jcajce.JcaCertStore; //导入依赖的package包/类
/**
 * Sign the given content using the private and public keys from the keySet, and return the encoded CMS (PKCS#7) data.
 * Use of direct signature and DER encoding produces a block that is verifiable by Android recovery programs.
 */
public static byte[] generate(KeySet keySet, byte[] content) {
    try {
        List certList = new ArrayList();
        CMSTypedData msg = new CMSProcessableByteArray(content);

        certList.add(keySet.getPublicKey());

        Store certs = new JcaCertStore(certList);

        CMSSignedDataGenerator gen = new CMSSignedDataGenerator();

        JcaContentSignerBuilder jcaContentSignerBuilder = new JcaContentSignerBuilder(keySet.getSignatureAlgorithm()).setProvider("SC");
        ContentSigner sha1Signer = jcaContentSignerBuilder.build(keySet.getPrivateKey());

        JcaDigestCalculatorProviderBuilder jcaDigestCalculatorProviderBuilder = new JcaDigestCalculatorProviderBuilder().setProvider("SC");
        DigestCalculatorProvider digestCalculatorProvider = jcaDigestCalculatorProviderBuilder.build();

        JcaSignerInfoGeneratorBuilder jcaSignerInfoGeneratorBuilder = new JcaSignerInfoGeneratorBuilder( digestCalculatorProvider);
        jcaSignerInfoGeneratorBuilder.setDirectSignature(true);
        SignerInfoGenerator signerInfoGenerator = jcaSignerInfoGeneratorBuilder.build(sha1Signer, keySet.getPublicKey());

        gen.addSignerInfoGenerator( signerInfoGenerator);

        gen.addCertificates(certs);

        CMSSignedData sigData = gen.generate(msg, false);
        return sigData.toASN1Structure().getEncoded("DER");

    } catch (Exception x) {
        throw new RuntimeException(x.getMessage(), x);
    }
}
 

import org.spongycastle.cert.jcajce.JcaCertStore; //导入依赖的package包/类
@Override
public byte[] sign(InputStream content) throws IOException 
{
  CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
  SignatureData input = new SignatureData(content);
  List<Certificate> certs = new ArrayList<Certificate>();
  for (int i = 0; i < chain.length; i ++) {
    certs.add(chain[i]);
  }

  try
  {
    Store certStore = new JcaCertStore(certs);

    Certificate cert = chain[0];
    org.spongycastle.asn1.x509.Certificate x509Cert =
      org.spongycastle.asn1.x509.Certificate.getInstance(ASN1Primitive.fromByteArray(cert.getEncoded()));

    ContentSigner sha256Signer = new JcaContentSignerBuilder("SHA256withRSA").build(privKey);
    gen.addSignerInfoGenerator(
             new JcaSignerInfoGeneratorBuilder(
             new JcaDigestCalculatorProviderBuilder().build())
             .build(sha256Signer, new X509CertificateHolder(x509Cert)));

    gen.addCertificates(certStore);
    CMSSignedData signedData = gen.generate(input, false);
    return signedData.getEncoded();
  }
  catch (Exception e)
  {
    e.printStackTrace();
  }
  throw new RuntimeException("Signing error, look at the stack trace");
}
 

import org.spongycastle.cert.jcajce.JcaCertStore; //导入依赖的package包/类
public void sendMail(String from, String to, String subject, String body)
        throws Exception {
    X509Certificate signerCert = getSignerCertificate();
    if (signerCert == null) {
        throw new IllegalStateException(
                "Load signing certificate and key first.");
    }

    ASN1EncodableVector signedAttrs = new ASN1EncodableVector();
    SMIMECapabilityVector caps = new SMIMECapabilityVector();

    caps.addCapability(SMIMECapability.aES256_CBC);
    caps.addCapability(SMIMECapability.dES_EDE3_CBC);
    caps.addCapability(SMIMECapability.dES_CBC);

    signedAttrs.add(new SMIMECapabilitiesAttribute(caps));

    // for encrypted responses
    IssuerAndSerialNumber issAndSer = new IssuerAndSerialNumber(
            new X500Name(signerCert.getSubjectDN().getName()),
            signerCert.getSerialNumber());
    signedAttrs.add(new SMIMEEncryptionKeyPreferenceAttribute(issAndSer));

    SMIMESignedGenerator gen = new SMIMESignedGenerator();
    gen.addSignerInfoGenerator(createSignerInfoGenerator(signedAttrs));

    Store certs = new JcaCertStore(Arrays.asList(signerCert));
    gen.addCertificates(certs);

    Session session = Session.getInstance(sessionProps, authenticator);

    Address fromUser = new InternetAddress(from);
    Address toUser = new InternetAddress(to);

    MimeMessage mimeMsg = new MimeMessage(session);
    mimeMsg.setFrom(fromUser);
    mimeMsg.setRecipient(Message.RecipientType.TO, toUser);
    mimeMsg.setSubject(subject);
    mimeMsg.setContent(body, "text/plain");
    mimeMsg.saveChanges();

    MimeMultipart mm = gen.generate(mimeMsg, "SC");
    MimeMessage signedMessage = new MimeMessage(session);
    Enumeration<?> headers = mimeMsg.getAllHeaderLines();
    while (headers.hasMoreElements()) {
        signedMessage.addHeaderLine((String) headers.nextElement());
    }
    signedMessage.setContent(mm);
    signedMessage.saveChanges();
    signedMessage.writeTo(new FileOutputStream(new File(Environment
            .getExternalStorageDirectory(), "signed.message")));

    Transport.send(signedMessage);
}