pgp加密解密过程java

PGP（Pretty Good Privacy）是一种加密和签名数据的标准，它使用了非对称加密算法和对称加密算法。下面是 PGP 加密解密的 Java 代码示例：

PGP 加密过程：

import java.io.*;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Date;
import org.bouncycastle.bcpg.*;
import org.bouncycastle.openpgp.*;
import org.bouncycastle.openpgp.bc.*;
import org.bouncycastle.openpgp.jcajce.*;
import org.bouncycastle.openpgp.operator.bc.*;
import org.bouncycastle.util.io.*;

public class PgpEncrypt {
    public static void encrypt(String inputFile, String publicKeyFile, String outputFile) {
        try {
            Security.addProvider(new BouncyCastleProvider());

            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            PGPCompressedDataGenerator compressedDataGenerator = new PGPCompressedDataGenerator(CompressionAlgorithmTags.ZIP);
            OutputStream compressedDataStream = compressedDataGenerator.open(baos);

            PGPLiteralDataGenerator literalDataGenerator = new PGPLiteralDataGenerator();
            OutputStream literalDataStream = literalDataGenerator.open(compressedDataStream, PGPLiteralData.BINARY, inputFile, new Date(), new byte[4096]);

            FileInputStream publicKeyInputStream = new FileInputStream(publicKeyFile);
            byte[] publicKeyBytes = new byte[publicKeyInputStream.available()];
            publicKeyInputStream.read(publicKeyBytes);
            publicKeyInputStream.close();
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(publicKeyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);

            PGPEncryptedDataGenerator encryptedDataGenerator = new PGPEncryptedDataGenerator(new JcePGPDataEncryptorBuilder(PGPEncryptedData.CAST5).setWithIntegrityPacket(true).setSecureRandom(new SecureRandom()).setProvider("BC"));
            encryptedDataGenerator.addMethod(new JcePublicKeyKeyEncryptionMethodGenerator(publicKey).setProvider("BC"));

            OutputStream encryptedDataStream = encryptedDataGenerator.open(literalDataStream, new byte[4096]);
            FileInputStream inputStream = new FileInputStream(inputFile);
            IOUtils.copy(inputStream, encryptedDataStream);
            inputStream.close();

            encryptedDataStream.close();
            literalDataStream.close();
            literalDataGenerator.close();
            compressedDataStream.close();
            compressedDataGenerator.close();

            FileOutputStream encryptedOutputStream = new FileOutputStream(outputFile);
            encryptedOutputStream.write(baos.toByteArray());
            encryptedOutputStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

PGP 解密过程：

import java.io.*;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import org.bouncycastle.bcpg.*;
import org.bouncycastle.openpgp.*;
import org.bouncycastle.openpgp.bc.*;
import org.bouncycastle.openpgp.jcajce.*;
import org.bouncycastle.util.io.*;

public class PgpDecrypt {
    public static void decrypt(String inputFile, String privateKeyFile, String privateKeyPassword, String outputFile) {
        try {
            Security.addProvider(new BouncyCastleProvider());

            FileInputStream inputStream = new FileInputStream(inputFile);
            PGPObjectFactory objectFactory = new PGPObjectFactory(PGPUtil.getDecoderStream(inputStream), new BcKeyFingerprintCalculator());
            Object object = objectFactory.nextObject();

            PGPEncryptedDataList encryptedDataList = null;
            if (object instanceof PGPEncryptedDataList) {
                encryptedDataList = (PGPEncryptedDataList) object;
            } else {
                encryptedDataList = (PGPEncryptedDataList) objectFactory.nextObject();
            }

            Iterator<PGPPublicKeyEncryptedData> iterator = encryptedDataList.getEncryptedDataObjects();
            PGPPrivateKey privateKey = null;
            PGPPublicKeyEncryptedData encryptedData = null;
            while (privateKey == null && iterator.hasNext()) {
                encryptedData = iterator.next();
                PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(IOUtils.toByteArray(new FileInputStream(privateKeyFile)));
                KeyFactory keyFactory = KeyFactory.getInstance("RSA");
                PrivateKey privateKeyObj = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
                if (encryptedData.getKeyID() == privateKeyObj.getEncoded()) {
                    privateKey = new JcePGPKeyConverter().getPGPPrivateKey(encryptedData.getKeyAlgorithm(), privateKeyObj);
                }
            }

            if (privateKey == null) {
                throw new IllegalArgumentException("Can't find private key with ID " + encryptedData.getKeyID());
            }

            InputStream decryptedDataStream = encryptedData.getDataStream(new JcePublicKeyDataDecryptorFactoryBuilder().setProvider("BC").build(privateKey));
            PGPObjectFactory pgpObjectFactory = new PGPObjectFactory(decryptedDataStream, new BcKeyFingerprintCalculator());

            Object message = pgpObjectFactory.nextObject();
            if (message instanceof PGPCompressedData) {
                PGPCompressedData compressedData = (PGPCompressedData) message;
                pgpObjectFactory = new PGPObjectFactory(compressedData.getDataStream(), new BcKeyFingerprintCalculator());
                message = pgpObjectFactory.nextObject();
            }

            PGPLiteralData literalData = (PGPLiteralData) message;
            InputStream literalDataStream = literalData.getInputStream();
            FileOutputStream outputStream = new FileOutputStream(outputFile);
            IOUtils.copy(literalDataStream, outputStream);

            outputStream.close();
            literalDataStream.close();
            decryptedDataStream.close();
            inputStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

上面的代码使用了 Bouncy Castle 库来实现 PGP 加密解密。需要注意的是，加密和解密时需要用到公钥和私钥，这里的公钥和私钥是以文件形式存储的，需要读取文件并转换成相应的对象使用。另外，解密时还需要输入私钥的密码。