Krypto

Krypto is a cryptography library for Multiplatform Kotlin 1.3.

https://github.com/korlibs/krypto

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Table of contents:

• SecureRandom
  • Using the SecureRandom instance
  • Seeding extra bytes
• Hash (MD4/MD5/SHA1/SHA256/SHA512)
• HMAC
• PBKDF2
• AES
• Using with gradle

SecureRandom

Krypto provides a SecureRandom object that extends the kotlin.random.Random class, but it generates cryptographic secure values. It is a singleton, and you cannot provide an initial seed.

Instead of a pseudo-random and reproducible, its result values are fully random, making it suitable for cryptographic purposes, and not suitable for reproductible results.

It uses SecureRandom on the JVM + PRNGFixes on Android. On Native POSIX (including Linux, macOS and iOS), it uses /dev/urandom, on Windows BCryptGenRandom

Using the SecureRandom instance

Since it is an object, you can use it directly as a Random instance:

val random: Random = SecureRandom

Seeding extra bytes

In addition to the standard kotlin Random interface, SecureRandom provides a method for seeding extra random bytes.

val bytes = byteArrayOf(1, 2, 3)
SecureRandom.addSeed(bytes)

Hash (MD4/MD5/SHA1/SHA256/SHA512)

fun ByteArray.hash(algo: HashFactory): ByteArray
fun ByteArray.md4()
fun ByteArray.md5()
fun ByteArray.sha1()
fun ByteArray.sha256()
fun ByteArray.sha512()

object MD4 : HashFactory
object MD5 : HashFactory
object SHA1 : HashFactory
object SHA256 : HashFactory
object SHA512 : HashFactory

open class HashFactory() {
    fun create(): Hash
}

fun HashFactory.digest(data: ByteArray): ByteArray

abstract class Hash {
    val chunkSize: Int
    val digestSize: Int
    
    fun reset(): Hash
    fun update(data: ByteArray, offset: Int, count: Int): Hash
    fun digest(): ByteArray
    fun digestOut(out: ByteArray)
}

HMAC

PBKDF2

AES

object AES {
    fun decryptAes128Cbc(encryptedMessage: ByteArray, cipherKey: ByteArray): ByteArray
    fun encryptEes128Cbc(plainMessage: ByteArray, cipherKey: ByteArray): ByteArray
}

Using with gradle

Requires Gradle 7.1.1 (JVM 11~17) for building and Kotlin >=1.7.21 for running:

build.gradle.kts

val kryptoVersion = "4.0.2"

// For multiplatform projects
kotlin {
    sourceSets {
        commonMain {
            dependencies {
                implementation("com.soywiz.korlibs.krypto:krypto:$kryptoVersion") 
            }
        }
    }
}

dependencies {
    // For JVM only
    implementation("com.soywiz.korlibs.krypto:krypto-jvm:$kryptoVersion") 
    // For Android only
    implementation("com.soywiz.korlibs.krypto:krypto-android:$kryptoVersion") 
    // For JS only
    implementation("com.soywiz.korlibs.krypto:krypto-js:$kryptoVersion") 
}