Generate Ecdsa Public Key From Private Key In Java
Generate Ecdsa Public Key From Private Key In Java 4,9/5 2784 reviews

Jun 18, 2014 In Java generating public private key using RSA algorithm is quite easy as it provides lib to do these tasks. In Java java.security package contains classes to do these operation. Generating public private key pairs. By using KeyPairGenerator class we can generate public/private key pairs as given below.

ECDSA with secp256k1 in Java: generate ECC keys, sign, verify
ECDSA-secp256k1-example.java
importorg.bouncycastle.util.encoders.Hex;
importorg.web3j.crypto.*;
importjava.math.BigInteger;
publicclassECCExample {
publicstaticStringcompressPubKey(BigIntegerpubKey) {
String pubKeyYPrefix = pubKey.testBit(0) ?'03':'02';
String pubKeyHex = pubKey.toString(16);
String pubKeyX = pubKeyHex.substring(0, 64);
return pubKeyYPrefix + pubKeyX;
}
publicstaticvoidmain(String[] args) throwsException {
//BigInteger privKey = Keys.createEcKeyPair().getPrivateKey();
BigInteger privKey =newBigInteger('97ddae0f3a25b92268175400149d65d6887b9cefaf28ea2c078e05cdc15a3c0a', 16);
BigInteger pubKey =Sign.publicKeyFromPrivate(privKey);
ECKeyPair keyPair =newECKeyPair(privKey, pubKey);
System.out.println('Private key: '+ privKey.toString(16));
System.out.println('Public key: '+ pubKey.toString(16));
System.out.println('Public key (compressed): '+ compressPubKey(pubKey));
String msg ='Message for signing';
byte[] msgHash =Hash.sha3(msg.getBytes());
Sign.SignatureData signature =Sign.signMessage(msgHash, keyPair, false);
System.out.println('Msg: '+ msg);
System.out.println('Msg hash: '+Hex.toHexString(msgHash));
System.out.printf('Signature: [v = %d, r = %s, s = %s]n',
signature.getV() -27,
Hex.toHexString(signature.getR()),
Hex.toHexString(signature.getS()));
System.out.println();
BigInteger pubKeyRecovered =Sign.signedMessageToKey(msg.getBytes(), signature);
System.out.println('Recovered public key: '+ pubKeyRecovered.toString(16));
boolean validSig = pubKey.equals(pubKeyRecovered);
System.out.println('Signature valid? '+ validSig);
}
}
pom.xml
<?xml version='1.0' encoding='UTF-8'?>
<projectxmlns='http://maven.apache.org/POM/4.0.0'
xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
xsi:schemaLocation='http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd'>
<modelVersion>4.0.0</modelVersion>
<groupId>bc-examples</groupId>
<artifactId>bc-examples</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>org.web3j</groupId>
<artifactId>crypto</artifactId>
<version>3.3.1</version>
</dependency>
</dependencies>
</project>

commented Apr 5, 2018

The expected output is as follows:

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commented Sep 16, 2018

java.security package contains ECDSA classes for generating the key pair, signing and verifying signatures.

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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.

Generate Ecdsa Public Key From Private Key In Java Tutorial

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.

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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:

Generate Ecdsa Public Key From Private Key In Java

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.

Generate Ecdsa Public Key From Private Key In Java Windows 10

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

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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 .

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

Generate Ecdsa Public Key From Private Key In Java Keystore

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

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