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net.corda.v5.crypto.extensions heading-link-icon

The corda-crypto-extensions package of the Corda Crypto API defines low-level crypto capabilities that can be used to extend functionality of the Corda Crypto Library by implementing them in a CPK Corda Package. A signed ZIP/JAR library of Java code packaged to be portable with all of its dependencies and version information contained within it. . For more information, see the documentation for the package in the Java API documentation.

Extending Supported Digest Algorithms heading-link-icon

The Corda Crypto Library implements a wide variety of digest algorithms out of the box. However, you can use a digest algorithm that is not supported by the library by simply implementing some interfaces and adding the code into the CPK with the CorDapp Corda Distributed Application. A Java (or any JVM targeting language) application built using the Corda build toolchain and CorDapp API to solve some problem that is best solved in a decentralized manner. code. Corda picks up any custom algorithms at runtime. R3 recommends adding custom digest code in a separate Java module.

Double SHA-256 is supported by the platform, but let us assume that you want to support Triple SHA-256 where the first pass calculates the message digest and subsequent passes calculate the digest of the previous pass result. The following sections show how to achieve this.

package com.example.crypto

import net.corda.v5.crypto.DigestAlgorithmName
import net.corda.v5.crypto.extensions.DigestAlgorithm
import java.io.InputStream
import java.security.MessageDigest

class TripleSha256Digest : DigestAlgorithm {
    companion object {
        const val ALGORITHM = "SHA-256-TRIPLE"
        const val STREAM_BUFFER_SIZE = DEFAULT_BUFFER_SIZE
    }

    override fun getAlgorithm() = ALGORITHM
    override fun getDigestLength() = 32
    override fun digest(bytes: ByteArray): ByteArray = bytes.sha256Bytes().sha256Bytes().sha256Bytes()
    override fun digest(inputStream: InputStream): ByteArray {
        val messageDigest = MessageDigest.getInstance(DigestAlgorithmName.SHA2_256.name)
        val buffer = ByteArray(STREAM_BUFFER_SIZE)
        while (true) {
            val read = inputStream.read(buffer)
            if (read <= 0) break
            messageDigest.update(buffer, 0, read)
        }
        return messageDigest.digest().sha256Bytes().sha256Bytes()
    }
}

private fun ByteArray.sha256Bytes(): ByteArray =
    MessageDigest.getInstance(DigestAlgorithmName.SHA2_256.name).digest(this)

package com.example.crypto;

import net.corda.v5.crypto.DigestAlgorithmName;
import net.corda.v5.crypto.extensions.DigestAlgorithm;
import org.jetbrains.annotations.NotNull;

import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class TripleSha256Digest implements DigestAlgorithm {
    public static String ALGORITHM = "SHA-256-TRIPLE";
    public static int STREAM_BUFFER_SIZE = 8192;

    @NotNull
    @Override
    public String getAlgorithm() {
        return ALGORITHM;
    }

    @Override
    public int getDigestLength() {
        return 32;
    }

    @NotNull
    @Override
    public byte[] digest(@NotNull byte[] bytes) {
        try {
            return sha256Bytes(sha256Bytes(sha256Bytes(bytes)));
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }

    @NotNull
    @Override
    public byte[] digest(@NotNull InputStream inputStream) {
        try {
            MessageDigest messageDigest = MessageDigest.getInstance(DigestAlgorithmName.SHA2_256.getName());
            byte[] buffer = new byte[STREAM_BUFFER_SIZE];
            while (true) {
                int read = inputStream.read(buffer);
                if (read <= 0) break;
                messageDigest.update(buffer, 0, read);
            }
            return sha256Bytes(sha256Bytes(messageDigest.digest()));
        } catch (NoSuchAlgorithmException | IOException e) {
            throw new RuntimeException(e);
        }
    }

    private static byte[] sha256Bytes(byte[] bytes) throws NoSuchAlgorithmException {
        return MessageDigest.getInstance(DigestAlgorithmName.SHA2_256.getName()).digest(bytes);
    }
}

package com.example.crypto

import net.corda.v5.crypto.extensions.DigestAlgorithm
import net.corda.v5.crypto.extensions.DigestAlgorithmFactory

/**
 * This class should show up in the jar manifest
 */
class TripleSha256 : DigestAlgorithmFactory {
    override fun getAlgorithm() = TripleSha256Digest.ALGORITHM

    override fun getInstance(): DigestAlgorithm = TripleSha256Digest()
}

package com.example.crypto;

import net.corda.v5.crypto.extensions.DigestAlgorithm;
import net.corda.v5.crypto.extensions.DigestAlgorithmFactory;
import org.jetbrains.annotations.NotNull;

public class TripleSha256 implements DigestAlgorithmFactory {

    @NotNull
    @Override
    public String getAlgorithm() {
        return TripleSha256Digest.ALGORITHM;
    }

    @NotNull
    @Override
    public DigestAlgorithm getInstance() {
        return new TripleSha256Digest();
    }
}


plugins {
    id 'org.jetbrains.kotlin.jvm'
    id 'net.corda.plugins.cordapp-cpk2'
}

description 'Corda Crypto Custom Digest One'

group 'com.example.crypto'

cordapp {
    targetPlatformVersion 999 as Integer
    workflow {
        name 'Custom Crypto Digest One CPK'
        versionId 1
        vendor 'R3'
    }
}

dependencies {
    cordaProvided platform("net.corda:corda-api:$cordaApiVersion")
    cordaProvided 'org.jetbrains.kotlin:kotlin-osgi-bundle'
    cordaProvided 'net.corda:corda-crypto'
    cordaProvided 'net.corda:corda-crypto-extensions'
}

plugins {
    id 'org.jetbrains.kotlin.jvm'
    id 'net.corda.plugins.cordapp-cpk2'
}

description 'Corda Crypto Custom Digest One'

group 'com.example.crypto'

cordapp {
    targetPlatformVersion 999 as Integer
    workflow {
        name 'Custom Crypto Digest One CPK'
        versionId 1
        vendor 'R3'
    }
}

dependencies {
    cordaProvided platform("net.corda:corda-api:$cordaApiVersion")
    cordaProvided 'net.corda:corda-crypto'
    cordaProvided 'net.corda:corda-crypto-extensions'
}

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