Java中的PKCS＃7解密代码

Question

I am very new to this area. I'm trying to develop a simply PCKS#7 encrypt/decrypt function in Java. The encrypt is without signing yet, I just want to test the encrypt/decrypt (the key is from a keystore)

Below is my encryption code.

private static byte[] encryptData() throws Exception {

    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    FileInputStream fIn = new FileInputStream(_keyStorePath);
    KeyStore keystore = KeyStore.getInstance("JKS");
    keystore.load(fIn, _password);
    Certificate cert = keystore.getCertificate("abc");
    fIn.close();

    // set up the generator
    CMSEnvelopedDataGenerator gen = new CMSEnvelopedDataGenerator();

    gen.addRecipientInfoGenerator(new JceKeyTransRecipientInfoGenerator((X509Certificate) cert).setProvider("BC"));

    // create the enveloped-data object
    CMSProcessable data = new CMSProcessableByteArray("Hello World!".getBytes());
    CMSEnvelopedData enveloped = gen.generate((CMSTypedData) data,new JceCMSContentEncryptorBuilder(CMSAlgorithm.DES_EDE3_CBC).setProvider("BC").build());
    return  enveloped.getEncoded();
}

How do I code a very simple decryption function(no verify signing) to decryption my file ?

I do some research online, 1 of the sample code I google it is `RecipientId recId = new RecipientId();

    recId.setSerialNumber(cert.getSerialNumber());
    recId.setIssuer(cert.getIssuerX500Principal().getEncoded());

    RecipientInformationStore recipients = enveloped.getRecipientInfos();
    RecipientInformation recipient = recipients.get(recId);

    byte[] recData = recipient.getContent(key, "BC");`

However, the "RecipientId recId = new RecipientId();" is not working, error msg : Cannot instantiate the type RecipientId

Thank you very much.

Answer 1

I think there is some changes for the new API.

Below should be the correct one,

X509Certificate cert9 = (X509Certificate) keystore.getCertificate("abc");
    KeyTransRecipientId recId = new JceKeyTransRecipientId(cert9.getIssuerX500Principal(), cert9.getSerialNumber());