FastKrypto

FastKrypto provides Kotlin Multiplatform bindings to the high-performance fastcrypto Rust library. It is the primary cryptography implementation used by ksui and other McXross Sui SDKs.

Get safe, cross-platform implementations of Ed25519, Secp256k1, Secp256r1, mnemonic/HD derivation, and common hashes.

Key Features

• Generate, sign, and verify keys for Ed25519, Secp256k1, and Secp256r1.
• Get recoverable signatures on the secp curves.
• Generate and derive keys from BIP-39 mnemonics.
• Have access to fast hash functions (SHA-256, Keccak, Blake2b-256, etc.) and HKDF/HMAC.
• Private key material is zeroized after use where possible.
• The library works on all major Kotlin targets.

Installation

Add the dependency to your KMP project. Use platform-specific artifacts for best results.

// commonMain
implementation("xyz.mcxross.fastkrypto:fastkrypto:0.1.3")

Platform artifacts are published:

implementation("xyz.mcxross.fastkrypto:fastkrypto-jvm:0.1.3")
implementation("xyz.mcxross.fastkrypto:fastkrypto-android:0.1.3")
implementation("xyz.mcxross.fastkrypto:fastkrypto-iosarm64:0.1.3")
// ... other native targets

For snapshots:

repositories {
    maven("https://central.sonatype.com/repository/maven-snapshots")
}

Quick Start

Key generation and signing (Ed25519)

import xyz.mcxross.fastkrypto.ed25519GenerateKeypair
import xyz.mcxross.fastkrypto.ed25519Sign
import xyz.mcxross.fastkrypto.ed25519Verify
 
val keypair = ed25519GenerateKeypair()
val message = "hello fastkrypto".encodeToByteArray()
 
val signature = ed25519Sign(keypair.privateKey, message)
val isValid = ed25519Verify(keypair.publicKey, message, signature)
 
println("Verified: $isValid")

All cryptographic operations can throw FastCryptoFfiException on invalid input lengths or bad data.

Mnemonic and key derivation

import xyz.mcxross.fastkrypto.mnemonicGenerate
import xyz.mcxross.fastkrypto.mnemonicValidate
import xyz.mcxross.fastkrypto.mnemonicDeriveKeypair
import xyz.mcxross.fastkrypto.SignatureScheme
 
val phrase = mnemonicGenerate(12u)
check(mnemonicValidate(phrase))
 
val path = "m/44'/784'/0'/0/0"
val keypair = mnemonicDeriveKeypair(phrase, "", SignatureScheme.ED25519, path)
 
println("Private key length: ${keypair.privateKey.size}")

Hashes

import xyz.mcxross.fastkrypto.sha256
import xyz.mcxross.fastkrypto.blake2b256
import xyz.mcxross.fastkrypto.keccak256
 
val data = "some data".encodeToByteArray()
 
val sha = sha256(data)
val blake = blake2b256(data)
val keccak = keccak256(data)

Supported Curves & Functions

Mnemonic / HD Derivation

• mnemonicGenerate(wordCount)
• mnemonicValidate(phrase)
• mnemonicToSeed(phrase, passphrase)
• mnemonicDerivePrivateKey(...)
• mnemonicDerivePublicKey(...)
• mnemonicDeriveKeypair(...)

Use standard BIP-44 paths (e.g. m/44'/784'/0'/0/0 for Sui).

Hashes & KDF

• sha256, sha3_256, sha512, sha3_512
• keccak256
• blake2b256
• hmac_sha3_256_digest
• hkdf_sha3_256_expand

Error Handling

Operations that can fail throw FastCryptoFfiException.

Reference & Resources