How to decrypt an encrypted text file using Algorithm SHA1withRSA .

Question

I have one encrypted file instance_demo_Encryp.xml and encrypted format is
MIMVwmYGCSqGSIb3DQEHAqCDFcJWMIMVwlECAQExCzAJBgUrDgMCGgUAMIMVvzoG
CSqGSIb3DQEHAaCDFb8qBIMVvyU8P3htbCB2ZXJzaW9uPScxLjAnIGVuY29kaW5n
PSdVVEYtOCcgPz4NCjx4YnJsaTp4YnJsIHhtbG5zOnhicmxpPSdodHRwOi8vd3d3
Lnhicmwub3JnLzIwMDMvaW5zdGFuY2UnIHhtbG5zOmxpbms9J2h0dHA6Ly93d3cu
eGJybC5vcmcvMjAwMy9saW5rYmFzZScgeG1sbnM6eGxpbms9J2h0dHA6Ly93d3cu
dzMub3JnLzE5OTkveGxpbmsnIHhtbG5zOnJlZj0naHR0cDovL3d3dy54YnJsLm9y
Zy8yMDA0L3JlZicgeG1sbnM6eGJybGR0PSdodHRwOi8veGJybC5vcmcvMjAwNS94
I want to decrypt and convert into original xml file.I am using below code but some error occurred javax.crypto.BadPaddingException: Data must start with zero.Please help
import java.io.*;
import java.math.BigInteger;
import java.net.URLEncoder;
import java.util.*;
import java.security.AlgorithmParameters;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPairGenerator;
import java.security.KeyStore;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
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.security.spec.RSAPublicKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import oracle.security.xmlsec.util.Base64;
import sun.misc.*;
//import org.bouncycastle.jce.provider.BouncyCastleProvider;
//import org.bouncycastle.jce.*;
public class EsignWithBC {
     public static final String KEY_STORE_PASSWORD = "password";
     public static void main(String[] args) {
           BASE64Encoder base64Encoder = new BASE64Encoder();
           BASE64Decoder base64Decoder = new BASE64Decoder();
          String record = null;
          char[] passwd = KEY_STORE_PASSWORD.toCharArray();
          String inputFileName = "webroot/cerFiles/instance_demo_Encryp.xml";
          try {
               KeyStore keyStore = KeyStore.getInstance("PKCS12");
               FileInputStream fis = new FileInputStream(
                         "D:\\eclipse_program\\xRnd\\WebRoot\\cerFiles\\AlicePFX.pfx");
               keyStore.load(fis, passwd);
               fis.close();
               Enumeration aliases = keyStore.aliases();
               while (aliases.hasMoreElements()) {
                    System.out.println(aliases.nextElement());
               /*FileInputStream fin = new FileInputStream("D:\\eclipse_program\\xRnd\\WebRoot\\cerFiles\\Alice.cer");
                CertificateFactory cf = CertificateFactory.getInstance("X.509");
                Collection c = cf.generateCertificates(fin);
                Iterator i = c.iterator();
                while (i.hasNext()) {
                   Certificate cert = (Certificate)i.next();
                   System.out.println("***************************************************");
                   System.out.println(cert.getPublicKey());
                   System.out.println("***************************************************");
                String filename= "D:\\eclipse_program\\xRnd\\WebRoot\\cerFiles\\Alice.cer";
                FileInputStream fis1 = new FileInputStream(filename);
                DataInputStream dis = new DataInputStream(fis1);
                CertificateFactory cf1 = CertificateFactory.getInstance("X.509");
                byte[] bytes = new byte[dis.available()];
                dis.readFully(bytes);
                ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
                Key key = null;
                while (bais.available() > 0) {
                   Certificate cert = cf1.generateCertificate(bais);
                   key = cert.getPublicKey();
                   System.out.println(cert.toString());
               // EsignWithBC obj = new EsignWithBC();
                //System.out.println(obj.createUrlFragment("alice's key","password","D:\\eclipse_program\\xRnd\\webroot\\cerFiles\\instance_demo_Encryp.xml"));
                FileReader fr = new FileReader(inputFileName);
                    BufferedReader br = new BufferedReader(fr);
                    byte text[] = null;
                     //System.out.println(text.toString());
               // Cipher cipher = Cipher.getInstance("SHA1withRSA");
                    KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
                    Signature sig = Signature.getInstance("SHA1withRSA");
                    Cipher rsaCipher = Cipher.getInstance("RSA");
                    String str = null;
                     byte[] cleartext1 = null;
                    rsaCipher.init(Cipher.DECRYPT_MODE, key);
                    System.out.println("********************************");
                    while ( (record=br.readLine()) != null ) {
                          text = base64Decoder.decodeBuffer(record);                         
                          cleartext1 = rsaCipher.doFinal(text);
                          //str = new String(cleartext1);
                          System.out.println(rsaCipher.doFinal(text));
                    System.out.println("********************************");
          } catch (Exception e) {
               e.printStackTrace();
}

Answer 1

SHA1withRSA is a signature algorithm and not an encryption. If all you have is the signature then you can never get back the original document. The best you can do is to check that the signature is valid but for that you will need the original document and the public key of the person who signed the document.
The code you post is not coherent and though I think can see what you are trying to do I am not willing to make guesses at this stage since it sounds like you are trying to do the impossible.