BIP32 Support

We support generating signatures for a BIP32 child key. Perform keygen once, and generate signatures for all BIP32 child keys!

Perform Derive Child Public-Key

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• Call SilentShard.ECDSA.deriveChildPublicKey() or SilentShard.EdDSA.deriveChildPublicKey() which returns Result of Success with Child Public-Key ByteArray or Failure with exception.

Example

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ECDSA

Example.kt

suspend fun deriveChildPublicKeyUsingKeyshare(
    keyId: String,
    trioSession: TrioSession,
    storageClient: StorageClient,
): ByteArray {
    return withContext(Dispatchers.IO) {
        //signature example for context
        trioSession.sign(
            keyId = keyId,
            message = messageHash,
            derivationPath = "m" // This is the default, use your desired path here. For e.g. 'm/1/2'
        ).getOrThrow()


        // Read the keyshare bytes from your StorageClient by keyId.
        val keyshare = (storageClient.read(keyId) as ReconcileStoreDao).currentKeyshare!!

        // child public key derivation
        SilentShard.ECDSA.deriveChildPublicKey(
            keyshare = keyshare,
            derivationPath = "m/1"
        ).getOrThrow()
    }
}

EdDSA

Example.kt

suspend fun deriveChildPublicKeyUsingKeyshare(
    keyId: String,
    trioSession: TrioSession,
    storageClient: StorageClient,
): ByteArray {
    return withContext(Dispatchers.IO) {
        //signature example for context
        trioSession.sign(
            keyId = keyId,
            message = messageHash,
            derivationPath = "m" // This is the default, use your desired path here. For e.g. 'm/1/2'
        ).getOrThrow()


        // Read the keyshare bytes from your StorageClient by keyId.
        val keyshare = (storageClient.read(keyId) as ReconcileStoreDao).currentKeyshare!!

        // child public key derivation
        SilentShard.EdDSA.deriveChildPublicKey(
            keyshare = keyshare,
            derivationPath = "m/1"
        ).getOrThrow()
    }
}

• When trioSession.sign() is called with a derivationPath, the signature is generated for the specified BIP32 derivation path.
• derivationPath is a string that specifies the path to the child key. It defaults to 'm' (no derivation) if not provided.

The derivation above computes a child public key from your existing key. For ECDSA sessions, hardDerivation(keyId, derivationPath) performs an MPC hardened derivation and returns a new child keyId that you can sign with directly.