Generating Rsa Key And Signing Java

admin

A RSA public key consists in several (big) integer values, and a RSA private key consists in also some integer values. Though the contents differ, a RSA public key and the corresponding RSA private key share a common mathematical structure, and, in particular, both include a specific value called the modulus.The public and private key of a given pair necessarily work over the same modulus. I have previously used the provider SunRsaSign for generating an RSA key pair that was used for signing data. But I am not sure if it is safe or if it makes sense to use a key pair generated by SunRsaSign for encrypting data. I have noticed that the provider SunJSSE contains: sun.security.rsa.RSAKeyPairGenerator.

/gta-v-cd-key-generator-v2-0-download.html. Generate and Install Code Signing Certificates for Windows and Java Usually when we think about SSL/TLS and certificates the first thing that comes to mind are the certificates used by a web server – and this makes sense because it is by far the most common usage for them. Jan 24, 2017 Let us learn the basics of generating and using RSA keys in Java. Java provides classes for the generation of RSA public and private key pairs with the package java.security. You can use RSA keys pairs in public key cryptography. Public key cryptography uses a pair of keys for encryption.

Generating Rsa Key And Signing Java Software

In order to be able to create a digital signature, you need a private key. (Its corresponding public key will be needed in order to verify the authenticity of the signature.)

In some cases the key pair (private key and corresponding public key) are already available in files. In that case the program can import and use the private key for signing, as shown in Weaknesses and Alternatives.

In other cases the program needs to generate the key pair. A key pair is generated by using the KeyPairGenerator class.

In this example you will generate a public/private key pair for the Digital Signature Algorithm (DSA). You will generate keys with a 1024-bit length.

Generating a key pair requires several steps:

Create a Key Pair Generator

The first step is to get a key-pair generator object for generating keys for the DSA signature algorithm.

As with all engine classes, the way to get a KeyPairGenerator object for a particular type of algorithm is to call the getInstance static factory method on the KeyPairGenerator class. This method has two forms, both of which hava a String algorithm first argument; one form also has a String provider second argument.

A caller may thus optionally specify the name of a provider, which will guarantee that the implementation of the algorithm requested is from the named provider. The sample code of this lesson always specifies the default SUN provider built into the JDK.

Put the following statement after the

line in the file created in the previous step, Prepare Initial Program Structure:

Initialize the Key Pair Generator

The next step is to initialize the key pair generator. All key pair generators share the concepts of a keysize and a source of randomness. The KeyPairGenerator class has an initialize method that takes these two types of arguments.

The keysize for a DSA key generator is the key length (in bits), which you will set to 1024.

The source of randomness must be an instance of the SecureRandom class that provides a cryptographically strong random number generator (RNG). For more information about SecureRandom, see the SecureRandom API Specification and the Java Cryptography Architecture Reference Guide .

Key

The following example requests an instance of SecureRandom that uses the SHA1PRNG algorithm, as provided by the built-in SUN provider. The example then passes this SecureRandom instance to the key-pair generator initialization method.

Some situations require strong random values, such as when creating high-value and long-lived secrets like RSA public and private keys. To help guide applications in selecting a suitable strong SecureRandom implementation, starting from JDK 8 Java distributions include a list of known strong SecureRandom implementations in the securerandom.strongAlgorithms property of the java.security.Security class. When you are creating such data, you should consider using SecureRandom.getInstanceStrong(), as it obtains an instance of the known strong algorithms.

Generate the Pair of Keys

The final step is to generate the key pair and to store the keys in PrivateKey and PublicKey objects.

Example of RSA generation, sign, verify, encryption, decryption and keystores in Java
RsaExample.java

Generating Rsa Key And Signing Java Free

importjavax.crypto.Cipher;
importjava.io.InputStream;
importjava.security.*;
importjava.util.Base64;
import staticjava.nio.charset.StandardCharsets.UTF_8;
publicclassRsaExample {
publicstaticKeyPairgenerateKeyPair() throwsException {
KeyPairGenerator generator =KeyPairGenerator.getInstance('RSA');
generator.initialize(2048, newSecureRandom());
KeyPair pair = generator.generateKeyPair();
return pair;
}
publicstaticKeyPairgetKeyPairFromKeyStore() throwsException {
//Generated with:
// keytool -genkeypair -alias mykey -storepass s3cr3t -keypass s3cr3t -keyalg RSA -keystore keystore.jks
InputStream ins =RsaExample.class.getResourceAsStream('/keystore.jks');
KeyStore keyStore =KeyStore.getInstance('JCEKS');
keyStore.load(ins, 's3cr3t'.toCharArray()); //Keystore password
KeyStore.PasswordProtection keyPassword =//Key password
newKeyStore.PasswordProtection('s3cr3t'.toCharArray());
KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry) keyStore.getEntry('mykey', keyPassword);
java.security.cert.Certificate cert = keyStore.getCertificate('mykey');
PublicKey publicKey = cert.getPublicKey();
PrivateKey privateKey = privateKeyEntry.getPrivateKey();
returnnewKeyPair(publicKey, privateKey);
}
publicstaticStringencrypt(StringplainText, PublicKeypublicKey) throwsException {
Cipher encryptCipher =Cipher.getInstance('RSA');
encryptCipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] cipherText = encryptCipher.doFinal(plainText.getBytes(UTF_8));
returnBase64.getEncoder().encodeToString(cipherText);
}
publicstaticStringdecrypt(StringcipherText, PrivateKeyprivateKey) throwsException {
byte[] bytes =Base64.getDecoder().decode(cipherText);
Cipher decriptCipher =Cipher.getInstance('RSA');
decriptCipher.init(Cipher.DECRYPT_MODE, privateKey);
returnnewString(decriptCipher.doFinal(bytes), UTF_8);
}
publicstaticStringsign(StringplainText, PrivateKeyprivateKey) throwsException {
Signature privateSignature =Signature.getInstance('SHA256withRSA');
privateSignature.initSign(privateKey);
privateSignature.update(plainText.getBytes(UTF_8));
byte[] signature = privateSignature.sign();
returnBase64.getEncoder().encodeToString(signature);
}
publicstaticbooleanverify(StringplainText, Stringsignature, PublicKeypublicKey) throwsException {
Signature publicSignature =Signature.getInstance('SHA256withRSA');
publicSignature.initVerify(publicKey);
publicSignature.update(plainText.getBytes(UTF_8));
byte[] signatureBytes =Base64.getDecoder().decode(signature);
return publicSignature.verify(signatureBytes);
}
publicstaticvoidmain(String.. argv) throwsException {
//First generate a public/private key pair
KeyPair pair = generateKeyPair();
//KeyPair pair = getKeyPairFromKeyStore();
//Our secret message
String message ='the answer to life the universe and everything';
//Encrypt the message
String cipherText = encrypt(message, pair.getPublic());
//Now decrypt it
String decipheredMessage = decrypt(cipherText, pair.getPrivate());
System.out.println(decipheredMessage);
//Let's sign our message
String signature = sign('foobar', pair.getPrivate());
//Let's check the signature
boolean isCorrect = verify('foobar', signature, pair.getPublic());
System.out.println('Signature correct: '+ isCorrect);
}
}

commented Oct 17, 2019

Generating Rsa Key And Signing Java Pdf

It's good thank you so much , How can i create base64 like jwt (header,body,sign) ?

commented Nov 26, 2019

Thanks for the code. One issue - using openjdk version '11.0.5-ea' 2019-10-15 requires the KeyStore.getInstance('JCEKS') code to be KeyStore.getInstance('PKCS12').

commented Dec 29, 2019

@stdunbar: It depends on your keyStore creation.

Generating Rsa Key And Signing Java
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment