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@sodot/sodot-node-sdk / BIP340

Class: BIP340

Class providing the functionality for the BIP340 protocol the FROST MPC protocol.

Example​

// Your server side creates a room for 3 parties using its API_KEY
// Creating a room uuid should always happen on the server side using your API_KEY
const N = 3;
const T = 2;
const bip340 = new BIP340();
const API_KEY = 'MY_API_KEY';
const keygenRoomUuid = await bip340.createRoom(N, API_KEY);
// All parties call initKeygen to get an BIP340InitKeygenResult, that contains a keygenId
const keygenInitResult = await bip340.initKeygen();
// All parties receive the keygenIds from all other parties
const keygenIds = [keygenId1, keygenId2];
// All parties join the keygen room
const keygenResult = await bip340.keygen(keygenRoomUuid, N, T, keygenInitResult, keygenIds);

// Pick the derivation path of the public key you want to sign for
const derivationPath = new Uint32Array([44,60,0,0,0]);
// Get the public key for the derivation path
const pubkey = await bip340.deriveTweakPubkey(keygenResult, derivationPath);
// To sign a message, create a signing room on the server side, using your API_KEY
const signingRoomUuid = await bip340.createRoom(T, API_KEY);
// your message in hex
const message = 'deadbeef';
// 2 parties join the signing room
const signature = await bip340.sign(signingRoomUuid, keygenResult, message, derivationPath);
// This signature can now be verified against pubkey

// Refreshing the secret key material
// Your server creates a room for 3 parties
const refreshRoomUuid = await bip340.createRoom(N, API_KEY);
// All parties join the refresh room
const refreshResult = await bip340.refresh(refreshRoomUuid, keygenResult);
// Note: refreshResult.pubkey == keygenResult.pubkey

// Signing using the new secret key material
// The room is again created by the server
const signingRoomUuid2 = await bip340.createRoom(T, API_KEY);
const message2 = 'deadbeefcafebabe';
const signature2 = await bip340.sign(signingRoomUuid2, refreshResult, message2, derivationPath);
// This signature can now be verified against pubkey

Extends​

  • BIP340

Constructors​

new BIP340()​

new BIP340(hostUrl?): BIP340

Constructs a new Ecdsa instance.

Parameters​

• hostUrl?: string

Returns​

BIP340

Overrides​

BIP340Internal.constructor

Methods​

createRoom()​

createRoom(numParties, apiKey): Promise<string>

Creates a room for the given number of parties. A room is a one time instance used to perform a single MPC operation(keygen/signing/refresh etc.) between parties

This function should be called in the backend so to not embed the API key in code that is distributed to the users. After the backend calls this function, the other parties can join the room by calling the relevant keygen/signing/refresh/etc. operation.

Parameters​

• numParties: number

The number of parties that will join the room. (an integer in range 1..65_535)

• apiKey: string

An API key is required to create a room

Returns​

Promise<string>

The UUID of the created room.

Inherited from​

BIP340Internal.createRoom

derivePrivateKeyFromXpriv()​

derivePrivateKeyFromXpriv(xpriv, derivationPath?): Promise<string>

Parses an xpriv string according to BIP-32 non-hardened, and returns the derived private key for a given BIP-32 non-hardened derivation path

Parameters​

• xpriv: string

A valid secp256k1 xpriv string.

• derivationPath?: Uint32Array

The BIP-32 non-hardened derivation path to use for computing the private key.

Returns​

Promise<string>

The derived private key of the xpriv.

Inherited from​

BIP340Internal.derivePrivateKeyFromXpriv

deriveTweakPubkey()​

deriveTweakPubkey(keygenResult, derivationPath?, tweak?): Promise<Uint8Array>

Returns the (optionally)derived and (optionally)tweaked public key for a keygenResult for a given BIP-32 non-hardened derivation path and an optional BIP-341 tweak

The tweak is used to tweak a public key with a BIP-341 Taproot tweaking, by supplying the T value from the BIP-341 Taproot specification(https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki#script-validation-rules): Let t = hash_<TapTweak>(p || km). If t ≥ 0xFFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE BAAEDCE6 AF48A03B BFD25E8C D0364141 (order of secp256k1), fail. Let Q = P + int(t)G.

Parameters​

• keygenResult: string | BIP340KeygenResult

An BIP340KeygenResult that contains a secret share, or the secret share as a string.

• derivationPath?: Uint32Array

The BIP-32 non-hardened derivation path to use for computing the public key.

• tweak?: string | Uint8Array

The tweak to be used for signing. Must be 32 bytes long, either as a Uint8Array or as a hex string.

Returns​

Promise<Uint8Array>

The derived public key of the keypair, you can sign for it by passing the same derivation_path and tweak to the sign method.

Inherited from​

BIP340Internal.deriveTweakPubkey

deriveTweakPubkeyFromXpub()​

deriveTweakPubkeyFromXpub(Xpub, derivationPath?, tweak?): Promise<Uint8Array>

Returns the derived public key for a given BIP-32 non-hardened derivation path and an extended public key (xpub).

Parameters​

• Xpub: string

The extended public key (xpub) of the keypair.

• derivationPath?: Uint32Array

The BIP-32 non-hardened derivation path to use for computing the public key.

• tweak?: string | Uint8Array

The tweak to be used for signing. Must be 32 bytes long, either as a Uint8Array or as a hex string.

Returns​

Promise<Uint8Array>

The extended public key (xpub) of the keypair as a hex string.

Inherited from​

BIP340Internal.deriveTweakPubkeyFromXpub

exportFullPrivateKey()​

exportFullPrivateKey(roomUuid, keygenResult, toExportID): Promise<undefined | string>

Combine all secret shares and export the full private key to a single party. Requires a threshold amount of parties to participate.

Parameters​

• roomUuid: string

The UUID of the export room.

• keygenResult: string | BIP340KeygenResult

The BIP340KeygenResult that contains the secret share of the private key to be extracted, or the secret key as a string.

• toExportID: string

The exportID outputs from exportID() of the party that will receive the private key, this must match between all parties, and the receiving party must participate.

Returns​

Promise<undefined | string>

The party being exported to will receive a string containing the full xpriv, while the rest will receive undefined.

Inherited from​

BIP340Internal.exportFullPrivateKey

exportID()​

exportID(keygenResult): Promise<string>

The party that expects to receive the private key needs to call this function before exportFullPrivatekey. It must then transmit the ID to threshold-1 parties, this can be done in an untrusted channel (as if the parties use different keys this will break) Once the parties have the exportID of the party they want to export the private key to, the party and the threshold-1 participants need to call exportFullPrivatekey with that ID.

Parameters​

• keygenResult: string | BIP340KeygenResult

The BIP340KeygenResult that contains the secret share to be used for key extraction, or the secret share as a string.

Returns​

Promise<string>

A string that contains a base58 string exportID.

Inherited from​

BIP340Internal.exportID

getXpub()​

getXpub(keygenResult): Promise<string>

Returns returns a base58 encoded extended public key (Xpub) derived from a BIP340KeygenResult. See BIP-32: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#serialization-format The Xpub can be used either via third party libraries or via BIP340.deriveTweakPubkeyFromXpub

Parameters​

• keygenResult: string | BIP340KeygenResult

An BIP340KeygenResult that contains the secret share of the private key, or the secret share as a string.

Returns​

Promise<string>

base58 encoded extended public key (Xpub).

Inherited from​

BIP340Internal.getXpub

importPrivateKeyImporter()​

importPrivateKeyImporter(roomUuid, threshold, privateKey, keygenInit, keygenIds): Promise<BIP340KeygenResult>

WARNING: Private key import is an advanced feature of the SDK. We strongly advise consulting with the Sodot team before using it, due to a full private key being imported from a different system. Secret shares generated from imported private keys will always have the risk of the private key having been compromised in the past or in the future in case the private key is not deleted after the import operation.

Importing a full private key, and sharing into a T-of-N sharing, the resultant key shares will be of the exact same public key as the full private key.

This is the method that an importing party (meaning one the party in possesion of the private key) should use for receiving a key share in the new T-of-N quorum.

Parameters​

• roomUuid: string

The UUID of the import room.

• threshold: number

The threshold of the keypair of the new quorum. (an integer in range 1..65_535)

• privateKey: string

The private key to be imported. (a hex string of length 64)

• keygenInit: BIP340InitKeygenResult

This must be the same BIP340InitKeygenResult the keygenId of was sent to the other parties.

• keygenIds: string[]

The keygenId outputs from initKeygen(), of all other parties we wish to be part of the new quorum with, keygenIds from all parties must be received through an authenticated communication channel.

Returns​

Promise<BIP340KeygenResult>

An BIP340KeygenResult that contains the public key as well as the secret data that can be used for signing.

Example​

const N = 3;
const T = 2;
// A private key is created in some external system.
// const privateKey = "b3ac...0d71"; // hex string with 64 hex chars
// Some time passes...
// Now this party wishes to be part of a new quorum of `2-of-3` sharing of the private key.

// The app server creates a room for N(= 3) parties.
const importRoomUuid = await bip340.createRoom(N, API_KEY);
// The other parties must join the import room using the `importPrivateKeyRecipient` method.
const keygenInitResult = await bip340.initKeygen(); // This the importing party
// This importing party will send its `keygenInitResult.keygenId` to all other parties.
// This party will also receive the `keygenId`s of all other parties of the new quorum.
const keygenIds = [keygenId1, keygenId2, keygenId3]; // Note that here we must include our own `keygenId` as well, the order of the ids doesn't matter.
const importKeygenResult = await bip340.importPrivateKeyImporter(importRoomUuid, T, privateKey, keygenInitResult, keygenIds);
// importKeygenResult can now be used for signing under the T(= 2) threshold with the same public key

Inherited from​

BIP340Internal.importPrivateKeyImporter

importPrivateKeyRecipient()​

importPrivateKeyRecipient(roomUuid, threshold, keygenInit, keygenIds): Promise<BIP340KeygenResult>

WARNING: Private key import is an advanced feature of the SDK. We strongly advise consulting with the Sodot team before using it, due to a full private key being imported from a different system. Secret shares generated from imported private keys will always have the risk of the private key having been compromised in the past or in the future in case the private key is not deleted after the import operation.

Importing a full private key, and sharing into a T-of-N sharing, the resultant key shares will be of the exact same public key as the full private key.

This is the method that a new party (meaning one that does not currently have the private key) should use for receiving a key share in the new T-of-N quorum. The method takes the same input parameters as keygen since for a new party joining the quorum the import operation is very similar to a keygen operation.

Parameters​

• roomUuid: string

The UUID of the import room.

• threshold: number

The threshold of the keypair of the new quorum. (an integer in range 1..65_535)

• keygenInit: BIP340InitKeygenResult

This must be the same BIP340InitKeygenResult the keygenId of was sent to the other parties.

• keygenIds: string[]

The keygenId outputs from initKeygen(), of all other parties we wish to be part of the new quorum with, keygenIds from all parties must be received through an authenticated communication channel.

Returns​

Promise<BIP340KeygenResult>

An BIP340KeygenResult that contains the public key as well as the secret data that can be used for signing.

Example​

const N = 3;
const T = 2;
// A private key is created in some external system.
// Some time passes...
// Now this party wishes to be part of a new quorum of `2-of-3` sharing of the private key.

// The app server creates a room for N(= 3) parties.
const importRoomUuid = await bip340.createRoom(N, API_KEY);
// The party with the private key must join the import room using the `importPrivateKeyImporter` method.
const keygenInitResult = await bip340.initKeygen(); // This is a new party
// This new party will send its `keygenInitResult.keygenId` to all other parties.
// This party will also receive the `keygenId`s of all other parties of the new quorum.
const keygenIds = [keygenId1, keygenId2, keygenId3]; // Note that here we must include our own `keygenId` as well, the order of the ids doesn't matter.
const importKeygenResult = await bip340.importPrivateKeyRecipient(importRoomUuid, T, keygenInitResult, keygenIds);
// importKeygenResult can now be used for signing under the T(= 2) threshold with the same public key

Inherited from​

BIP340Internal.importPrivateKeyRecipient

initKeygen()​

initKeygen(): Promise<BIP340InitKeygenResult>

All parties must call this function before calling keygen. All parties receive an BIP340InitKeygenResult as an output from this function. The BIP340InitKeygenResult.keygenId must be sent through an authenticated communication channel to all other devices we wish to perform keygen with. Once we have the keygenId-s of all parties, then keygen can be called with the same BIP340InitKeygenResult.keygenSecret as was given here.

Returns​

Promise<BIP340InitKeygenResult>

An BIP340InitKeygenResult that contains a base58 string keygenId and keygenSecret.

Inherited from​

BIP340Internal.initKeygen

keygen()​

keygen(roomUuid, numParties, threshold, keygenInit, keygenIds): Promise<BIP340KeygenResult>

Generate a keypair for the given number of parties and threshold.

Parameters​

• roomUuid: string

The UUID of the keygen room.

• numParties: number

The number of parties that will join the keygen room. (an integer in range 1..65_535)

• threshold: number

The threshold of the keypair that will be generated. (an integer in range 1..65_535)

• keygenInit: BIP340InitKeygenResult

This must be the same BIP340InitKeygenResult the keygenId of was sent to the other parties.

• keygenIds: string[]

The keygenId outputs from initKeygen of all other parties we wish to perform keygen with, these must have been received through an authenticated communication channel.

Returns​

Promise<BIP340KeygenResult>

An BIP340 KeygenResult that includes the public key of the generated keypair.

Example​

// Your server side creates a room for 3 parties using its API_KEY
const N = 5;
const T = 3;
const bip340 = new BIP340();
const API_KEY = 'MY_API_KEY';
const keygenRoomUuid = await bip340.createRoom(N, API_KEY);

// All parties call initKeygen to get an BIP340InitKeygenResult, that contains a keygenId
const keygenInitResult = await bip340.initKeygen();
// All parties receive the keygenIds from all other parties
const keygenIds = [keygenId1, keygenId2, keygenId3, keygenId4];
// All parties join the keygen room
const keygenResult = await bip340.keygen(keygenRoomUuid, N, T, keygenInitResult, keygenIds);
// keygenResult.pubkey is now distributed between all 5 parties, such that each 3 parties can sign a message

Inherited from​

BIP340Internal.keygen

offlineExportFullPrivateKey()​

offlineExportFullPrivateKey(keygenResults): Promise<string>

Receives as input an array of threshold BIP340KeygenResults and locally computes the full private key (spriv). The main use case for this function is in an offline recovery setting where keygen results are collected manually and used to recover the full private key on an air-gapped server/device.

Parameters​

• keygenResults: string[] | BIP340KeygenResult[]

An array of threshold BIP340KeygenResults that each contain a secret share of the private key to be locally extracted, or an array of secret shares as strings

Returns​

Promise<string>

A string containing the full xpriv.

Inherited from​

BIP340Internal.offlineExportFullPrivateKey

refresh()​

refresh(roomUuid, keygenResult): Promise<BIP340KeygenResult>

Used for refreshing the secret material of all parties without altering the public key at all. Takes an BIP340KeygenResult as input and returns a new one with the same public key but with fresh key material. Be careful to delete the BIP340KeygenResult given as input before it is certain that all devices have properly stored the fresh BIP340KeygenResult that is output. Note that the new BIP340KeygenResults may only be used with each other, attempting to use older BIP340KeygenResults with newer ones for signing will result in failure. The motivation for using refresh is to enhance security by switching the secret key material frequently, this means that an adversary will need to compromise multiple devices at the same time in order to compromise the private key.

Parameters​

• roomUuid: string

The UUID of the refresh room.

• keygenResult: string | BIP340KeygenResult

The BIP340KeygenResult that contains the secret share that will be refreshed, or the secret share as a string.

Returns​

Promise<BIP340KeygenResult>

A new BIP340KeygenResult with the same pubkey as the input but with fresh secret key material.

Example​

const N = 5;
const T = 3;
const bip340 = new BIP340();
const API_KEY = 'MY_API_KEY';
// An BIP340KeygenResult is generated
const keygenResult = await bip340.keygen(...);
// Some time passes ...

// We now refresh the secret key material of our public key
// Your server creates a room for 3 parties
const refreshRoomUuid = await bip340.createRoom(N, API_KEY);
// All parties now join the refresh room using their current secret key material

// Option 1: Refresh the secret using the generated keygenResult
const refreshedKeygenResult = await bip340.refresh(refreshRoomUuid, keygenResult)

// Option 2:  Refresh the secret using a secret share string
let secretShareString: string = keygenResult.secretShare;
const refreshedKeygenResult = await bip340.refresh(refreshRoomUuid, secretShareString)
// Note: refreshedKeygenResult.pubkey == keygenResult.pubkey
// refreshedKeygenResult can now be used for signing under the same T threshold, as well as be refreshed again

Inherited from​

BIP340Internal.refresh

reshareNewParty()​

reshareNewParty(roomUuid, oldThreshold, newThreshold, keygenInit, keygenIds): Promise<BIP340KeygenResult>

WARNING: Key resharing is an advanced feature of the SDK. We strongly advise consulting with the Sodot team before using it, as incorrect usage might lead to the detriment of the private key security. To use the feature correctly, developers using this feature must make sure that at least n - t + 1 parties of the t-of-n signing quorum delete their current shares before using the resharing of the private key. Also, after resharing, the resharing operation must not be considered complete until such deletion has occurred. Since deleting a share cannot be guaranteed cryptographically, it must be guaranteed by the software architecture (hence, by the developers using the SDK).

Resharing the private key of the t-of-n quorum of signers, the resultant key shares will be of the exact same public key as the previous quorum. Resharing should be used in cases where we aim to modify the current t-of-n quorum with a new quorum with newT-of-newN signers for the same public key.

This is the method that a new party (meaning one that does not currently have a key share) should use for receiving a key share in the new newT-of-newN quorum. The method takes the same input parameters as keygen since for a new party joining the quorum the reshare operation is very similar to a keygen operation. In order to receive the keygenIds of parties that are already a part of the quorum, those parties will need to call exportID() and send the result to the parties in the new quorum.

Parameters​

• roomUuid: string

The UUID of the reshare room.

• oldThreshold: number

The threshold of the existing quorum. (an integer in range 1..65_535)

• newThreshold: number

The threshold of the keypair of the new quorum. (an integer in range 1..65_535)

• keygenInit: BIP340InitKeygenResult

This must be the same BIP340InitKeygenResult the keygenId of was sent to the other parties.

• keygenIds: string[]

The keygenId outputs from initKeygen() - for new parties / exportID() - for parties remaining in the quorum, of all other parties we wish to be part of the new quorum with, keygenIds from all parties must be received through an authenticated communication channel.

Returns​

Promise<BIP340KeygenResult>

An BIP340KeygenResult that contains the public key as well as the secret data that can be used for signing.

Example​

const N = 5;
const T = 3;
const newN = 6;
const newT = 5;
// A signing quorum of `3-of-5` is set up without this party.
// Some time passes...
// Now this party wishes to be part of a new quorum of `5-of-6`.

// The app server creates a room for newN(= 6) parties.
const reshareRoomUuid = await bip340.createRoom(newN, API_KEY);
// At least T(= 3) parties now join the reshare room using the current secret key material (this will be done using `reshareRemainingParty`), all new parties will then join the reshare room using their `initKeygenResult` using `reshareNewParty`.
const keygenInitResult = await bip340.initKeygen(); // This is a new party
// This new party will send its `keygenInitResult.keygenId` to all other parties.
// This party will also receive the `keygenId`s of all other parties of the new quorum.
const keygenIds = [keygenId1, keygenId2, ..., keygenId6]; // Note that here we must include our own `keygenId` as well, the order of the ids doesn't matter.
const reshareKeygenResult = await bip340.reshareNewParty(reshareRoomUuid, T, newT, keygenInitResult, keygenIds);
// reshareKeygenResult can now be used for signing under the newT(= 5) threshold with the same public key, as well as be reshared again

Inherited from​

BIP340Internal.reshareNewParty

reshareRemainingParty()​

reshareRemainingParty(roomUuid, newThreshold, keygenResult, keygenIds): Promise<BIP340KeygenResult>

WARNING: Key resharing is an advanced feature of the SDK. We strongly advise consulting with the Sodot team before using it, as incorrect usage might lead to the detriment of the private key security. To use the feature correctly, developers using this feature must make sure that at least n - t + 1 parties of the t-of-n signing quorum delete their current shares before using the resharing of the private key. Also, after resharing, the resharing operation must not be considered complete until such deletion has occurred. Since deleting a share cannot be guaranteed cryptographically, it must be guaranteed by the software architecture (hence, by the developers using the SDK).

Resharing the private key of the t-of-n quorum of signers, the resultant key shares will be of the exact same public key as the previous quorum. Resharing should be used in cases where we aim to modify the current t-of-n quorum with a new quorum with newT-of-newN signers for the same public key.

This is the method that a remaining party (meaning one that does currently have a key share) should use for receiving a new key share in the new newT-of-newN quorum. The method takes the same input parameters as reshareNewParty except that it will use its existing BIP340KeygenResult instead of a new BIP340InitKeygenResult. In order to receive the keygenIds of parties that are already a part of the quorum, those parties will need to call exportID() and send the result to the parties in the new quorum.

Parameters​

• roomUuid: string

The UUID of the reshare room.

• newThreshold: number

The threshold of the keypair of the new quorum. (an integer in range 1..65_535)

• keygenResult: string | BIP340KeygenResult

The BIP340KeygenResult that is used for signing with the existing t-of-n quorum, or the secret share as a string.

• keygenIds: string[]

The keygenId outputs from initKeygen() - for new parties / exportID() - for parties remaining in the quorum, of all other parties we wish to be part of the new quorum with, keygenIds from new parties must be received through an authenticated communication channel, keygenIds from remaining parties in the quorum can be sent through any communication channel.

Returns​

Promise<BIP340KeygenResult>

An BIP340KeygenResult that contains the public key as well as the secret data that can be used for signing.

Example​

const N = 5;
const T = 3;
const newN = 6;
const newT = 5;
// A signing quorum of `3-of-5` is set up with this party.
const keygenResult = bip340.keygen(...);
// Some time passes...
// Now this party wishes to be part of a new quorum of `5-of-6`.

// The app server creates a room for newN(= 6) parties.
const reshareRoomUuid = await bip340.createRoom(newN, API_KEY);
// At least T(= 3) parties now join the reshare room using the current secret key material (this will be done using `reshareRemainingParty`), all new parties will then join the reshare room using their `initKeygenResult` using `reshareNewParty`.
const keygenId = await bip340.exportID(keygenResult); // This is a remaining party
// This remaining party will send its `keygenId` to all other parties (new - via an authenticated channel and remaining - via any channel).
// This party will also receive the `keygenId`s of all other parties of the new quorum (new - via an authenticated channel and remaining - via any channel).
const keygenIds = [keygenId1, keygenId2, ..., keygenId6]; // Note that here we must include our own `keygenId` as well, the order of the ids doesn't matter.
 // Option 1:  Reshare the private key using the generated keygenResult
const reshareKeygenResult = await bip340.reshareRemainingParty(reshareRoomUuid, newT, keygenResult, keygenIds);

// Option 2:  Reshare the private key using a secret share string
let secretShareString: string = keygenResult.secretShare;
const reshareKeygenResult = await bip340.reshareRemainingParty(reshareRoomUuid, newT, secretShareString, keygenIds);
// reshareKeygenResult can now be used for signing under the newT(= 5) threshold with the same public key, as well as be reshared again

Inherited from​

BIP340Internal.reshareRemainingParty

sign()​

sign(roomUuid, keygenResult, msg, derivationPath?, tweak?): Promise<Uint8Array>

Sign a message with the secret share contained in an BIP340KeygenResult. Notice that unlike ECDSA, in BIP340 there's no need to hash the message before signing it.
This supports BIP-341 Taproot tweaking by supplying the T value from the BIP-341 Taproot specification(https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki#script-validation-rules):
Let t = hash_<TapTweak>(p || km).
If t ≥ 0xFFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE BAAEDCE6 AF48A03B BFD25E8C D0364141 (order of secp256k1), fail.
Let Q = P + int(t)G.

Parameters​

• roomUuid: string

The UUID of the signing room.

• keygenResult: string | BIP340KeygenResult

The BIP340KeygenResult that contains the secret share to be used for signing, or the secret share as a string.

• msg: string | Uint8Array

The message to be signed. Either as a Uint8Array or as a hex string.

• derivationPath?: Uint32Array

The BIP-32 non-hardened derivation path to use for signing msg.

• tweak?: string | Uint8Array

The tweak to be used for signing. Must be 32 bytes long, either as a Uint8Array or as a hex string.

Returns​

Promise<Uint8Array>

The signature of the message, this signature can be verified using keygenResult.pubkey

Example​

// To sign a message, create a signing room on the server side, using your API_KEY
const N = 5;
const T = 3;
const bip340 = new BIP340();
const API_KEY = 'MY_API_KEY';
// A BIP340KeygenResult is generated
const keygenResult = await bip340.keygen(...);

const signingRoomUuid = await bip340.createRoom(T, API_KEY);

// Pick the derivation path of the public key you want to sign for
const derivationPath = new Uint32Array([44, 60, 0, 0, 0]);

// Option 1: Derive public key using the secret share from keygenResult
const pubkey = await bip340.deriveTweakPubkey(keygenResult, derivationPath);

// Option 2: Derive public key using an extended public key (Xpub) for more flexibility
const Xpub = await bip340.getXpub(keygenResult);
const pubkeyFromXpub = await bip340.deriveTweakPubkeyFromXpub(Xpub, derivationPath);

// The message as a hex string
const message = 'deadbeef';

// 3 parties join the signing room
// Option 1: Sign using the generated keygenResult
const signature = await bip340.sign(signingRoomUuid, keygenResult, message, derivationPath);

// Option 2: sign using a secret share string
let secretShareString: string = keygenResult.secretShare;
const signature = await bip340.sign(signingRoomUuid, secretShareString, message, derivationPath);
// The signature can be verified against pubkey or pubkeyFromXpub

Inherited from​

BIP340Internal.sign