Asymmetric Encryption (Box)

Asymmetric encryption, or Public-Key Cryptography, allows two parties to securely exchange messages without ever sharing their private keys. Kodium implements authenticated encryption using Curve25519, XSalsa20, and Poly1305.

Basic Usage

To securely send a message, the sender needs the recipient's Public Key and their own Private Key.

1. Generating Keys

// Alice and Bob generate their respective key pairs
val alice = Kodium.generateKeyPair()
val bob = Kodium.generateKeyPair()

2. Encrypting a Message (Alice to Bob)

Alice wants to send a secret message to Bob. She uses her private key and Bob's public key.

val message = "The eagle flies at midnight.".encodeToByteArray()

// Alice encrypts a message for Bob
val encryptedResult = Kodium.encryptToEncodedString(
    mySecretKey = alice,
    theirPublicKey = bob.getPublicKey(),
    data = message
)

// The result is a Result<String> containing the Base58Check encoded ciphertext
val cipherTextString = encryptedResult.getOrThrow()

3. Decrypting a Message (Bob from Alice)

Bob receives the cipherTextString from Alice. He decrypts it using his private key and Alice's public key. This not only decrypts the message but also authenticates that it truly came from Alice.

val decryptedResult = Kodium.decryptFromEncodedString(
    mySecretKey = bob,
    theirPublicKey = alice.getPublicKey(),
    data = cipherTextString
)

decryptedResult.onSuccess { decryptedBytes ->
    println("Decrypted: ${decryptedBytes.decodeToString()}")
}.onFailure { error ->
    println("Decryption failed or message was forged: ${error.message}")
}