Files
Master-TI-2/security/TP1/VerSig.java
T
2024-10-25 10:05:52 +02:00

100 lines
3.5 KiB
Java
Executable File

/*
* Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle or the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
import java.io.*;
import java.security.*;
import java.security.spec.*;
class VerSig {
public static void main(String[] args) {
/* Verify a DSA signature */
if (args.length != 3) {
System.out.println("Usage: VerSig publickeyfile signaturefile datafile");
}
else try{
/* import encoded public key */
FileInputStream keyfis = new FileInputStream(args[0]);
byte[] encKey = new byte[keyfis.available()];
keyfis.read(encKey);
keyfis.close();
X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(encKey);
KeyFactory keyFactory = KeyFactory.getInstance("DSA", "SUN");
PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);
/* input the signature bytes */
FileInputStream sigfis = new FileInputStream(args[1]);
byte[] sigToVerify = new byte[sigfis.available()];
sigfis.read(sigToVerify );
sigfis.close();
/* create a Signature object and initialize it with the public key */
Signature sig = Signature.getInstance("SHA1withDSA", "SUN");
sig.initVerify(pubKey);
/* Update and verify the data */
FileInputStream datafis = new FileInputStream(args[2]);
BufferedInputStream bufin = new BufferedInputStream(datafis);
byte[] buffer = new byte[1024];
int len;
while (bufin.available() != 0) {
len = bufin.read(buffer);
sig.update(buffer, 0, len);
};
bufin.close();
boolean verifies = sig.verify(sigToVerify);
System.out.println("signature verifies: " + verifies);
} catch (Exception e) {
System.err.println("Caught exception " + e.toString());
};
}
}