6

I'm writing a program which takes as input from the console - the name of a zip file, name of a zip file to be made containig the (de/en)crypted files generated from the first zip and a file containing the public key. I get the exception when decrypting:

Exception in thread "main" java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException : algid parse error, not a sequence
at sun.security.rsa.RSAKeyFactory.engineGeneratePrivate(RSAKeyFactory.java:217)
at java.security.KeyFactory.generatePrivate(KeyFactory.java:372)
at com.Main.makePrivateKey(Main.java:148)
at com.Main.decrypt(Main.java:40)
at com.Main.main(Main.java:182)
Caused by: java.security.InvalidKeyException: IOException : algid parse error, not a sequence
at sun.security.pkcs.PKCS8Key.decode(PKCS8Key.java:351)
at sun.security.pkcs.PKCS8Key.decode(PKCS8Key.java:356)
at sun.security.rsa.RSAPrivateCrtKeyImpl.<init>(RSAPrivateCrtKeyImpl.java:91)
at sun.security.rsa.RSAPrivateCrtKeyImpl.newKey(RSAPrivateCrtKeyImpl.java:75)
at sun.security.rsa.RSAKeyFactory.generatePrivate(RSAKeyFactory.java:316)
at sun.security.rsa.RSAKeyFactory.engineGeneratePrivate(RSAKeyFactory.java:213)
... 4 more

Can't figure out why because the I use the rigth spec in the makePrivateKey method. The keys I'm testing with are(one line for a key each in a separate file):

Public key:

MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCE3pA746UfpC8sFk8ZJp0yupyJqj5jy6cjdxUYoP7mCm7c0mqQDeCcDNBYW2eSozCioPrH/9L+CDQEPLYakoem+jFnUKDH5+pru/0PJTJJF8Xh/ZT9eJlvsYBr1/qSfICf6RTs7kzwq9IuSZBw7/tfNEF9i0A8FVox6HOopXod1QIDAQAB

Private key:

MIICXQIBAAKBgQCE3pA746UfpC8sFk8ZJp0yupyJqj5jy6cjdxUYoP7mCm7c0mqQDeCcDNBYW2eSozCioPrH/9L+CDQEPLYakoem+jFnUKDH5+pru/0PJTJJF8Xh/ZT9eJlvsYBr1/qSfICf6RTs7kzwq9IuSZBw7/tfNEF9i0A8FVox6HOopXod1QIDAQABAoGANOFrYBqK5lvu1koOswDWQZFZqcSSzh8IZyoGwGWa7S0r0EECXlDXmuPSq8e9IfRG8ALHrH+ZlrbnFOSgyVSWHfpj3aH+qknoSX5TW2rMQHih8865xuqheMQ+RTZ7+BRDqNsYkzxB/Z8mqzpoJQSYf+H7nWxdDCgAJVYZzxl3DmUCQQD32iEjnwiwUjii8slcmvCEZl+z84DWNdvJOg6Z38sI4AvrfpKc1WAcDg1rNZCKrRgokh54wpLt08cpFcrD04c3AkEAiTzDmc0bdgfg5wj6xHFZpYlBwiGm/bjOR2PS57P0GNU5PsDllRbFqIuzArITutO5lvZZImzuYz7Lf+cQ73pxUwJBAOdEwmdaneDo17A0m2+to3/nhqWDMVSwLMU3RyiNigZeCMFU+bkd4PBMrHi9IoJDwacZsRU9eZwxYEUV8H2Jg0ECQEEkOqRSm2pXKwX/WSjNtQPCNxhy6NUeV6vDUmTxIjh3XYjP/ynZeVEbnoj1BjB0N2/U11Jj6nPpZqb7gyppMEkCQQCoGdVYDipU+hMMnvxa0zOIyQc/a+HE0lESqn+2ZPafYi9Z1RldRMvUXhP8U7s+OuhRwprdw2ivvOFrnWyz9lL2

The code for the program is bellow . Any help is wellcomed :)

package com;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Security;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.Enumeration;
import java.util.Scanner;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;

import javax.crypto.Cipher;

public class Main {

public final static int BUFFER_SIZE = 117;

public static void decrypt(String originalZipFileName, String newZipFileName, String privateKeyFileName) throws Exception {
    byte[] buffer = new byte[BUFFER_SIZE];  

    ZipFile originalZipFile = new ZipFile(originalZipFileName); 
    ZipOutputStream newZipFile = new ZipOutputStream(new FileOutputStream(newZipFileName));

    Enumeration<? extends ZipEntry> zipEntries = originalZipFile.entries();

    String privateKey = getKeyString(privateKeyFileName);
    PrivateKey key = makePrivateKey(privateKey);

    Cipher cipher = Cipher.getInstance("RSA");

    cipher.init(Cipher.DECRYPT_MODE, key);
    File file = new File("temp.txt");

    while(zipEntries.hasMoreElements()){

        ZipEntry entry = zipEntries.nextElement();          

        ZipEntry copy = new ZipEntry(entry.getName());      
        newZipFile.putNextEntry(copy);

        int read;           
        InputStream inputEntry = originalZipFile.getInputStream(entry);
        OutputStream outputFile = new FileOutputStream(file);

        while((read = inputEntry.read(buffer)) != -1){              
            outputFile.write(cipher.doFinal(buffer), 0, read);
        }

        InputStream inputTempFile = new FileInputStream(file);

        while((read = inputTempFile.read(buffer)) != -1){
            newZipFile.write(buffer, 0, read);
        }

        newZipFile.closeEntry();
        inputEntry.close();
        inputTempFile.close();
        outputFile.close();
        file.delete();
    }
    newZipFile.close();
}

public static void encrypt(String originalZipFileName, String newZipFileName, String publicKeyFileName) throws Exception{

    byte[] buffer = new byte[BUFFER_SIZE];  

    ZipFile originalZipFile = new ZipFile(originalZipFileName); 
    ZipOutputStream newZipFile = new ZipOutputStream(new FileOutputStream(newZipFileName));

    Enumeration<? extends ZipEntry> zipEntries = originalZipFile.entries();

    String publicKey = getKeyString(publicKeyFileName);
    PublicKey key = makePublicKey(publicKey);

    Cipher cipher = Cipher.getInstance("RSA");

    cipher.init(Cipher.ENCRYPT_MODE, key);
    File file = new File("temp.txt");

    while(zipEntries.hasMoreElements()){

        ZipEntry entry = zipEntries.nextElement();          

        ZipEntry copy = new ZipEntry(entry.getName());      
        newZipFile.putNextEntry(copy);

        int read;           
        InputStream inputEntry = originalZipFile.getInputStream(entry);
        OutputStream outputFile = new FileOutputStream(file);

        while((read = inputEntry.read(buffer)) != -1){              
            outputFile.write(cipher.doFinal(buffer), 0, read);
        }

        InputStream inputTempFile = new FileInputStream(file);

        while((read = inputTempFile.read(buffer)) != -1){
            newZipFile.write(buffer, 0, read);
        }

        newZipFile.closeEntry();
        inputEntry.close();
        inputTempFile.close();
        outputFile.close();
        file.delete();
    }
    newZipFile.close();
}   

public static String getKeyString(String fileName){

    String key = new String();
    try {
        BufferedReader buf = new BufferedReader(new FileReader(fileName));
        key = buf.readLine();       
    } catch ( IOException e) {
        e.printStackTrace();
    }   

    return key.trim();
}

public static PublicKey makePublicKey(String stored) throws GeneralSecurityException {
    byte[] data = Base64.getDecoder().decode(stored);
    X509EncodedKeySpec spec = new  X509EncodedKeySpec(data);
    KeyFactory fact = KeyFactory.getInstance("RSA");
    return fact.generatePublic(spec);
}

public static PrivateKey makePrivateKey(String stored) throws GeneralSecurityException {
    byte[] data = Base64.getDecoder().decode(stored);
    PKCS8EncodedKeySpec spec = new  PKCS8EncodedKeySpec(data);
    KeyFactory fact = KeyFactory.getInstance("RSA");
    return fact.generatePrivate(spec);
}

public static void main(String[] args) throws Exception {

    Scanner scan = new Scanner(System.in);

    System.out.println("Enter type of operation:");
    String line = scan.nextLine();

    if(line.equals("encrypt")){
        System.out.println("Enter name of original ZIP file:");
        String originalZipFileName = scan.nextLine();

        System.out.println("Enter name of new ZIP file:");
        String newZipFileName = scan.nextLine();

        System.out.println("Enter name of file containg public key:");
        String publicKeyFileName = scan.nextLine();

        encrypt(originalZipFileName, newZipFileName, publicKeyFileName);        
    }
    if(line.equals("decrypt")){
        System.out.println("Enter name of original ZIP file:");
        String originalZipFileName = scan.nextLine();

        System.out.println("Enter name of new ZIP file:");
        String newZipFileName = scan.nextLine();

        System.out.println("Enter name of file containg private key:");
        String privateKeyFileName = scan.nextLine();

        decrypt(originalZipFileName, newZipFileName, privateKeyFileName);       
    }       

}

}
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2 Answers 2

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19

Your private key is not in PKCS#8 format. You have to add key algorithm information to it to make it PKCS#8 and then it will work.

Probably you should alter the way you generate keys to have them in PKCS#8 format. But since I know nothing on that I will just show how to update key to it in your application using BouncyCastle library:

@Test
public void testKey() throws Exception {
    String privKeyStr = "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";
    byte[] data = Base64.getDecoder().decode(privKeyStr);

    /* Add PKCS#8 formatting */
    ASN1EncodableVector v = new ASN1EncodableVector();
    v.add(new ASN1Integer(0));
    ASN1EncodableVector v2 = new ASN1EncodableVector();
    v2.add(new ASN1ObjectIdentifier(PKCSObjectIdentifiers.rsaEncryption.getId()));
    v2.add(DERNull.INSTANCE);
    v.add(new DERSequence(v2));
    v.add(new DEROctetString(data));
    ASN1Sequence seq = new DERSequence(v);
    byte[] privKey = seq.getEncoded("DER");

    PKCS8EncodedKeySpec spec = new  PKCS8EncodedKeySpec(privKey);
    KeyFactory fact = KeyFactory.getInstance("RSA");
    PrivateKey key = fact.generatePrivate(spec);
    Assert.assertNotNull("Failed to generate the private key", key);
}
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5 Comments

Wow nice. Never knew it needed so much more work. But know I get this exception Exception in thread "main" javax.crypto.BadPaddingException: Decryption error at sun.security.rsa.RSAPadding.unpadV15(RSAPadding.java:380) at sun.security.rsa.RSAPadding.unpad(RSAPadding.java:291) at com.sun.crypto.provider.RSACipher.doFinal(RSACipher.java:363) at com.sun.crypto.provider.RSACipher.engineDoFinal(RSACipher.java:389) at javax.crypto.Cipher.doFinal(Cipher.java:2165) at com.Main.decrypt(Main.java:67) at com.Main.main(Main.java:201) Any Idea why?
PS: I generated the keys from here travistidwell.com/blog/2013/09/06/…
You can generate asymmetric keys, for example, with java.security.KeyPairGenerator. Would you please accept the answer and ask another question about padding?
OK. Question is here: stackoverflow.com/questions/31944374/…
God bless you sir/mam! Worked like a charm!
1

This answer is a complement for divanov's answer.

PKCS#8 format contain some fields, not just the most important part private key.

Private-Key Information Syntax

This section gives the syntax for private-key information.

Private-key information shall have ASN.1 type PrivateKeyInfo:

  PrivateKeyInfo ::= SEQUENCE {
    version                   Version,
    privateKeyAlgorithm       PrivateKeyAlgorithmIdentifier,
    privateKey                PrivateKey,
    attributes           [0]  IMPLICIT Attributes OPTIONAL }

  Version ::= INTEGER

  PrivateKeyAlgorithmIdentifier ::= AlgorithmIdentifier

  PrivateKey ::= OCTET STRING

  Attributes ::= SET OF Attribute

The fields of type PrivateKeyInfo have the following meanings:

version is the syntax version number, for compatibility with future revisions of this document. It shall be 0 for this version of the document.

privateKeyAlgorithm identifies the private-key algorithm. One example of a private-key algorithm is PKCS #1's rsaEncryption [PKCS#1].

privateKey is an octet string whose contents are the value of the private key. The interpretation of the contents is defined in the registration of the private-key algorithm. For an RSA private key, for example, the contents are a BER encoding of a value of type RSAPrivateKey.

attributes is a set of attributes. These are the extended information that is encrypted along with the private-key information.

You can find the corresponding between Private-Key Information Syntax and divanov's code. Like:

v.add(new ASN1Integer(0));//add version part to a PKCS#8
v.add(new DERSequence(v2));//add algorithm part to a PKCS#8
v.add(new DEROctetString(data));//add private key part to a PKCS#8

More detail is here.

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