KCrypt: Secure Key Management for Multiplatform Apps

KCrypt is a Kotlin Multiplatform Mobile (KMM) library that provides a secure and unified way to manage encryption keys across iOS and Android platforms. It abstracts the complexities of key generation, encryption, and storage, thereby providing you with a unique key that can be used for cryptographic purposes, allowing you to focus on building secure and robust multiplatform applications.

Kcrypt also provides a secured storage where in key-value pairs.

Index

• Features
• Upcoming features
• Use case
• Usage
• Compatibility
• Contributing
• Test Reports
• License

Features

• Secure Key Generation: KCrypt handles the generation of secure encryption keys based on platform-specific best practices and provides you with a unique key that persists as long as the app stays installed.
• Cross-Platform Compatibility: Build multiplatform applications with shared encryption logic that works consistently on iOS and Android.
• Storage of encrypted key-value pairs

Upcoming features

• Ability to maintain multiple keys.

Use case

If you want a secure String that you can use for encryption or any other cryptographic reasons, KCrpyt provides you with one. For example: If we take the Realm Kmm library, in order to encrypt the db we need to provide it with a key

val config = RealmConfiguration
      .Builder(
        schema = setOf(
          UserDbEntity::class,
          ClipboardDbEntity::class
        )
      )
      .schemaVersion(dbVersion)
      .encryptionKey(getKCrypt().getEncryptionKey()!!)
      .build()

We need to provide a key to the encryptionKey() method. Here comes KCrypt which provides a unique secure key across Android and iOS, that can be passed to the encryptionKey() method. Similarly, KCrypt can be used for other encryption/cryptographic purposes where one needs an encryption key.

Or

If you want to store data using key value pairs in an encrypted format, KCrypt is here for you. For example: If we want to store a value how we would normally store in encrypted shared preferences or keychain, we can do so as follows:

getKCrypt().saveString("stringVal", "my sample string")
val storedString = getKCrypt().getString("stringVal") // returns "my sample string"

Usage

To get started with KCrypt in your KMM project, follow these steps:

1. Add the KCrypt dependency to your shared module's build.gradle.kts:

// build.gradle.kts in the shared module
kotlin {
    sourceSets {
        val commonMain by getting {
            dependencies {
                implementation("io.github.abhriyaroy:KCrypt:0.0.15")
            }
        }
    }
}

2. Use KCrypt in your shared code:

• For Encryption key:

// Shared code
import studio.zebro.kcrypt.getKCrypt

val kCrypt = getKCrypt()

// to get encryption key in 64 byte array
val encryptionKeyByteArray : ByteArray = kCrypt.getEncryptionKey()

// to save a custom encryption key
kCrypt.saveEncryptionKey("MyCustomKey", isHexString = false)

// to get encryption key as a String representation of 64 byte array
val encryptionkeyInString : String = kCrypt.getEncryptionKeyToHexString()

// to convert byte array to string
val convertedByteArrayInString : String = kCrypt.byteArrayToHexString(encryptionKeyByteArray)

// to convert hex string to byte array
val convertedStringInByteArray : ByteArray = kCrypt.hexStringToByteArray(encryptionkeyInString)

• For Key-Value pairs:

// Shared code
import studio.zebro.kcrypt.getKCrypt

val kCrypt = getKCrypt()

// save string value
kCrypt.saveString("stringVal", "my string")
// retrieve saved string value
kCrypt.getString("stringVal")

// save int value
kCrypt.saveInt("intVal", 101)
// retrieve saved int value
kCrypt.getInt("intVal")

// save float value
kCrypt.saveFloat("floatVal", 100.5f)
// retrieve float value
kCrypt.getFloat("floatVal")

// save double value
kCrypt.saveDouble("doubleVal", 599.4)
// retrieve double value
kCrypt.getDouble("doubleVal")

// save boolean value
kCrypt.saveBoolean("booleanVal", true)
// retrieve boolean value
kCrypt.getBoolean("booleanVal")

Compatibility

KCrypt is designed to work with Kotlin Multiplatform Mobile projects targeting both iOS and Android platforms.

• Minimum Android version: Android 8.0 (API level 26)
• Minimum iOS version: iOS 13.0

Contributing

Contributions to KCrypt are welcome! Feel free to open issues for feature requests, bug reports, or general discussions. Pull requests are also appreciated.

Test Reports

You can view the latest test reports here.

License

This project is licensed under the MIT License.