verify File Sign With Decrypt

Description

Demo Code


import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.Date;
import javax.crypto.Cipher;

public class Main{

    /*www.  j a  va 2 s  .co m*/
    public static final String KEY_STORE = "JKS";
    public static final String X509 = "X.509";
    
    private static final int CACHE_SIZE = 2048;
    
    private static final int MAX_DECRYPT_BLOCK = 128;
    
    public static boolean verifyFileSignWithDecrypt(
            String encryptedFilePath, String sign, String certificatePath)
            throws Exception {
        byte[] encryptedData = fileToByte(encryptedFilePath);
        byte[] data = decryptByPublicKey(encryptedData, certificatePath);
        return verifySign(data, sign, certificatePath);
    }
    
    public static byte[] fileToByte(String filePath) throws Exception {
        byte[] data = new byte[0];
        File file = new File(filePath);
        if (file.exists()) {
            FileInputStream in = new FileInputStream(file);
            ByteArrayOutputStream out = new ByteArrayOutputStream(2048);
            byte[] cache = new byte[CACHE_SIZE];
            int nRead = 0;
            while ((nRead = in.read(cache)) != -1) {
                out.write(cache, 0, nRead);
                out.flush();
            }
            out.close();
            in.close();
            data = out.toByteArray();
        }
        return data;
    }
    
    public static byte[] decryptByPublicKey(byte[] encryptedData,
            String certificatePath) throws Exception {
        PublicKey publicKey = getPublicKey(certificatePath);
        Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // ?????????
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet,
                        MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen
                        - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }
    
    public static boolean verifySign(byte[] data, String sign,
            String certificatePath) throws Exception {
        // ?????
        X509Certificate x509Certificate = (X509Certificate) getCertificate(certificatePath);
        // ????
        PublicKey publicKey = x509Certificate.getPublicKey();
        // ??????
        Signature signature = Signature.getInstance(x509Certificate
                .getSigAlgName());
        signature.initVerify(publicKey);
        signature.update(data);
        return signature.verify(Base64.decode(sign));
    }
    
    private static PublicKey getPublicKey(String certificatePath)
            throws Exception {
        Certificate certificate = getCertificate(certificatePath);
        PublicKey publicKey = certificate.getPublicKey();
        return publicKey;
    }
    
    private static Certificate getCertificate(String certificatePath)
            throws Exception {
        CertificateFactory certificateFactory = CertificateFactory
                .getInstance(X509);
        FileInputStream in = new FileInputStream(certificatePath);
        Certificate certificate = certificateFactory
                .generateCertificate(in);
        in.close();
        return certificate;
    }
    
    private static Certificate getCertificate(String keyStorePath,
            String alias, String password) throws Exception {
        KeyStore keyStore = getKeyStore(keyStorePath, password);
        Certificate certificate = keyStore.getCertificate(alias);
        return certificate;
    }
    
    private static KeyStore getKeyStore(String keyStorePath, String password)
            throws Exception {
        FileInputStream in = new FileInputStream(keyStorePath);
        KeyStore keyStore = KeyStore.getInstance(KEY_STORE);
        keyStore.load(in, password.toCharArray());
        in.close();
        return keyStore;
    }
}
verify File Sign With Decrypt - Java Security

Description

Demo Code

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