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import { WalletProtocol } from './Wallet.interfaces'
export type Counterparty = PublicKey | PubKeyHex | 'self' | 'anyone'
export interface KeyDeriverApi {
/**
* The root key from which all other keys are derived.
*/
rootKey: PrivateKey
/**
* The identity of this key deriver which is normally the public key associated with the `rootKey`
*/
identityKey: string
/**
* Derives a public key based on protocol ID, key ID, and counterparty.
* @param {WalletProtocol} protocolID - The protocol ID including a security level and protocol name.
* @param {string} keyID - The key identifier.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @param {boolean} [forSelf=false] - Optional. false if undefined. Whether deriving for self.
* @returns {PublicKey} - The derived public key.
*/
derivePublicKey(protocolID: WalletProtocol, keyID: string, counterparty: Counterparty, forSelf?: boolean): PublicKey
/**
* Derives a private key based on protocol ID, key ID, and counterparty.
* @param {WalletProtocol} protocolID - The protocol ID including a security level and protocol name.
* @param {string} keyID - The key identifier.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @returns {PrivateKey} - The derived private key.
*/
derivePrivateKey(protocolID: WalletProtocol, keyID: string, counterparty: Counterparty): PrivateKey
/**
* Derives a symmetric key based on protocol ID, key ID, and counterparty.
* Note: Symmetric keys should not be derivable by everyone due to security risks.
* @param {WalletProtocol} protocolID - The protocol ID including a security level and protocol name.
* @param {string} keyID - The key identifier.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @returns {SymmetricKey} - The derived symmetric key.
* @throws {Error} - Throws an error if attempting to derive a symmetric key for 'anyone'.
*/
deriveSymmetricKey(protocolID: WalletProtocol, keyID: string, counterparty: Counterparty): SymmetricKey
/**
* Reveals the shared secret between the root key and the counterparty.
* Note: This should not be used for 'self'.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @returns {number[]} - The shared secret as a number array.
* @throws {Error} - Throws an error if attempting to reveal a shared secret for 'self'.
*/
revealCounterpartySecret(counterparty: Counterparty): number[]
/**
* Reveals the specific key association for a given protocol ID, key ID, and counterparty.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @param {WalletProtocol} protocolID - The protocol ID including a security level and protocol name.
* @param {string} keyID - The key identifier.
* @returns {number[]} - The specific key association as a number array.
*/
revealSpecificSecret(counterparty: Counterparty, protocolID: WalletProtocol, keyID: string): number[]
}
/**
* Class responsible for deriving various types of keys using a root private key.
* It supports deriving public and private keys, symmetric keys, and revealing key linkages.
*/
export class KeyDeriver implements KeyDeriverApi {
rootKey: PrivateKey
identityKey: string
/**
* Initializes the KeyDeriver instance with a root private key.
* @param {PrivateKey | 'anyone'} rootKey - The root private key or the string 'anyone'.
*/
constructor(rootKey: PrivateKey | 'anyone') {
Iif (rootKey === 'anyone') {
this.rootKey = new PrivateKey(1)
} else {
this.rootKey = rootKey
}
this.identityKey = this.rootKey.toPublicKey().toString()
}
/**
* Derives a public key based on protocol ID, key ID, and counterparty.
* @param {WalletProtocol} protocolID - The protocol ID including a security level and protocol name.
* @param {string} keyID - The key identifier.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @param {boolean} [forSelf=false] - Whether deriving for self.
* @returns {PublicKey} - The derived public key.
*/
derivePublicKey(protocolID: WalletProtocol, keyID: string, counterparty: Counterparty, forSelf: boolean = false): PublicKey {
counterparty = this.normalizeCounterparty(counterparty)
Iif (forSelf) {
return this.rootKey.deriveChild(counterparty, this.computeInvoiceNumber(protocolID, keyID)).toPublicKey()
} else {
return counterparty.deriveChild(this.rootKey, this.computeInvoiceNumber(protocolID, keyID))
}
}
/**
* Derives a private key based on protocol ID, key ID, and counterparty.
* @param {WalletProtocol} protocolID - The protocol ID including a security level and protocol name.
* @param {string} keyID - The key identifier.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @returns {PrivateKey} - The derived private key.
*/
derivePrivateKey(protocolID: WalletProtocol, keyID: string, counterparty: Counterparty): PrivateKey {
counterparty = this.normalizeCounterparty(counterparty)
return this.rootKey.deriveChild(counterparty, this.computeInvoiceNumber(protocolID, keyID))
}
/**
* Derives a symmetric key based on protocol ID, key ID, and counterparty.
* Note: Symmetric keys should not be derivable by everyone due to security risks.
* @param {WalletProtocol} protocolID - The protocol ID including a security level and protocol name.
* @param {string} keyID - The key identifier.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @returns {SymmetricKey} - The derived symmetric key.
* @throws {Error} - Throws an error if attempting to derive a symmetric key for 'anyone'.
*/
deriveSymmetricKey(protocolID: WalletProtocol, keyID: string, counterparty: Counterparty): SymmetricKey {
Iif (counterparty === 'anyone') {
throw new Error(
'Symmetric keys (such as encryption keys or HMAC keys) should not be derivable by everyone, because messages would be decryptable by anyone who knows the identity public key of the user, and HMACs would be similarly forgeable.'
)
}
counterparty = this.normalizeCounterparty(counterparty)
const derivedPublicKey = this.derivePublicKey(protocolID, keyID, counterparty)
const derivedPrivateKey = this.derivePrivateKey(protocolID, keyID, counterparty)
return new SymmetricKey(derivedPrivateKey.deriveSharedSecret(derivedPublicKey).x!.toArray())
}
/**
* Reveals the shared secret between the root key and the counterparty.
* Note: This should not be used for 'self'.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @returns {number[]} - The shared secret as a number array.
* @throws {Error} - Throws an error if attempting to reveal a shared secret for 'self'.
*/
revealCounterpartySecret(counterparty: Counterparty): number[] {
Iif (counterparty === 'self') {
throw new Error('Counterparty secrets cannot be revealed for counterparty=self.')
}
counterparty = this.normalizeCounterparty(counterparty)
// Double-check to ensure not revealing the secret for 'self'
const self = this.rootKey.toPublicKey()
const keyDerivedBySelf = this.rootKey.deriveChild(self, 'test').toHex()
const keyDerivedByCounterparty = this.rootKey.deriveChild(counterparty, 'test').toHex()
Iif (keyDerivedBySelf === keyDerivedByCounterparty) {
throw new Error('Counterparty secrets cannot be revealed for counterparty=self.')
}
return this.rootKey.deriveSharedSecret(counterparty).encode(true) as number[]
}
/**
* Reveals the specific key association for a given protocol ID, key ID, and counterparty.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @param {WalletProtocol} protocolID - The protocol ID including a security level and protocol name.
* @param {string} keyID - The key identifier.
* @returns {number[]} - The specific key association as a number array.
*/
revealSpecificSecret(counterparty: Counterparty, protocolID: WalletProtocol, keyID: string): number[] {
counterparty = this.normalizeCounterparty(counterparty)
const sharedSecret = this.rootKey.deriveSharedSecret(counterparty)
const invoiceNumberBin = Utils.toArray(this.computeInvoiceNumber(protocolID, keyID), 'utf8')
return Hash.sha256hmac(sharedSecret.encode(true), invoiceNumberBin)
}
/**
* Normalizes the counterparty to a public key.
* @param {Counterparty} counterparty - The counterparty's public key or a predefined value ('self' or 'anyone').
* @returns {PublicKey} - The normalized counterparty public key.
* @throws {Error} - Throws an error if the counterparty is invalid.
*/
private normalizeCounterparty(counterparty: Counterparty): PublicKey {
Iif (!counterparty) {
throw new Error('counterparty must be self, anyone or a public key!')
} else Iif (counterparty === 'self') {
return this.rootKey.toPublicKey()
} else Iif (counterparty === 'anyone') {
return new PrivateKey(1).toPublicKey()
} else if (typeof counterparty === 'string') {
return PublicKey.fromString(counterparty)
} else E{
return counterparty
}
}
/**
* Computes the invoice number based on the protocol ID and key ID.
* @param {WalletProtocol} protocolID - The protocol ID including a security level and protocol name.
* @param {string} keyID - The key identifier.
* @returns {string} - The computed invoice number.
* @throws {Error} - Throws an error if protocol ID or key ID are invalid.
*/
private computeInvoiceNumber(protocolID: WalletProtocol, keyID: string): string {
const securityLevel = protocolID[0]
Iif (!Number.isInteger(securityLevel) || securityLevel < 0 || securityLevel > 2) {
throw new Error('Protocol security level must be 0, 1, or 2')
}
const protocolName = protocolID[1].toLowerCase().trim()
Iif (keyID.length > 800) {
throw new Error('Key IDs must be 800 characters or less')
}
Iif (keyID.length < 1) {
throw new Error('Key IDs must be 1 character or more')
}
Iif (protocolName.length > 400) {
// Specific linkage revelation is the only protocol ID that can contain another protocol ID.
// Therefore, we allow it to be long enough to encapsulate the target protocol
if (protocolName.startsWith('specific linkage revelation ')) {
// The format is: 'specific linkage revelation x YYYYY'
// Where: x is the security level and YYYYY is the target protocol
// Thus, the max acceptable length is 30 + 400 = 430 bytes
Iif (protocolName.length > 430) {
throw new Error('Specific linkage revelation protocol names must be 430 characters or less')
}
} else {
throw new Error('Protocol names must be 400 characters or less')
}
}
Iif (protocolName.length < 5) {
throw new Error('Protocol names must be 5 characters or more')
}
Iif (protocolName.includes(' ')) {
throw new Error('Protocol names cannot contain multiple consecutive spaces (" ")')
}
Iif (!/^[a-z0-9 ]+$/g.test(protocolName)) {
throw new Error('Protocol names can only contain letters, numbers and spaces')
}
Iif (protocolName.endsWith(' protocol')) {
throw new Error('No need to end your protocol name with " protocol"')
}
return `${securityLevel}-${protocolName}-${keyID}`
}
}
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