@hpke/dhkem-x448/esm/src/x448.js

A Hybrid Public Key Encryption (HPKE) module extension for X448

import { x448 } from "@noble/curves/ed448";
import { base64UrlToBytes, DeriveKeyPairError, DeserializeError, EMPTY, KEM_USAGES, LABEL_DKP_PRK, LABEL_SK, NotSupportedError, SerializeError, XCryptoKey, } from "@hpke/common";
const ALG_NAME = "X448";
export class X448 {
    constructor(hkdf) {
        Object.defineProperty(this, "_hkdf", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "_nPk", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        Object.defineProperty(this, "_nSk", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: void 0
        });
        this._hkdf = hkdf;
        this._nPk = 56;
        this._nSk = 56;
    }
    async serializePublicKey(key) {
        try {
            return await this._serializePublicKey(key);
        }
        catch (e) {
            throw new SerializeError(e);
        }
    }
    async deserializePublicKey(key) {
        try {
            return await this._importRawKey(key, true);
        }
        catch (e) {
            throw new DeserializeError(e);
        }
    }
    async serializePrivateKey(key) {
        try {
            return await this._serializePrivateKey(key);
        }
        catch (e) {
            throw new SerializeError(e);
        }
    }
    async deserializePrivateKey(key) {
        try {
            return await this._importRawKey(key, false);
        }
        catch (e) {
            throw new DeserializeError(e);
        }
    }
    async importKey(format, key, isPublic) {
        try {
            if (format === "raw") {
                return await this._importRawKey(key, isPublic);
            }
            // jwk
            if (key instanceof ArrayBuffer) {
                throw new Error("Invalid jwk key format");
            }
            return await this._importJWK(key, isPublic);
        }
        catch (e) {
            throw new DeserializeError(e);
        }
    }
    async generateKeyPair() {
        try {
            const rawSk = x448.utils.randomPrivateKey();
            const sk = new XCryptoKey(ALG_NAME, rawSk, "private", KEM_USAGES);
            const pk = await this.derivePublicKey(sk);
            return { publicKey: pk, privateKey: sk };
        }
        catch (e) {
            throw new NotSupportedError(e);
        }
    }
    async deriveKeyPair(ikm) {
        try {
            const dkpPrk = await this._hkdf.labeledExtract(EMPTY.buffer, LABEL_DKP_PRK, new Uint8Array(ikm));
            const rawSk = await this._hkdf.labeledExpand(dkpPrk, LABEL_SK, EMPTY, this._nSk);
            const sk = new XCryptoKey(ALG_NAME, new Uint8Array(rawSk), "private", KEM_USAGES);
            return {
                privateKey: sk,
                publicKey: await this.derivePublicKey(sk),
            };
        }
        catch (e) {
            throw new DeriveKeyPairError(e);
        }
    }
    async derivePublicKey(key) {
        try {
            return await this._derivePublicKey(key);
        }
        catch (e) {
            throw new DeserializeError(e);
        }
    }
    async dh(sk, pk) {
        try {
            return await this._dh(sk, pk);
        }
        catch (e) {
            throw new SerializeError(e);
        }
    }
    _serializePublicKey(k) {
        return new Promise((resolve) => {
            resolve(k.key.buffer);
        });
    }
    _serializePrivateKey(k) {
        return new Promise((resolve) => {
            resolve(k.key.buffer);
        });
    }
    _importRawKey(key, isPublic) {
        return new Promise((resolve, reject) => {
            if (isPublic && key.byteLength !== this._nPk) {
                reject(new Error("Invalid length of the key"));
            }
            if (!isPublic && (key.byteLength !== this._nSk)) {
                reject(new Error("Invalid length of the key"));
            }
            resolve(new XCryptoKey(ALG_NAME, new Uint8Array(key), isPublic ? "public" : "private", isPublic ? [] : KEM_USAGES));
        });
    }
    _importJWK(key, isPublic) {
        return new Promise((resolve, reject) => {
            if (key.kty !== "OKP") {
                reject(new Error(`Invalid kty: ${key.kty}`));
            }
            if (key.crv !== "X448") {
                reject(new Error(`Invalid crv: ${key.crv}`));
            }
            if (isPublic) {
                if (typeof key.d !== "undefined") {
                    reject(new Error("Invalid key: `d` should not be set"));
                }
                if (typeof key.x !== "string") {
                    reject(new Error("Invalid key: `x` not found"));
                }
                resolve(new XCryptoKey(ALG_NAME, base64UrlToBytes(key.x), "public"));
            }
            else {
                if (typeof key.d !== "string") {
                    reject(new Error("Invalid key: `d` not found"));
                }
                resolve(new XCryptoKey(ALG_NAME, base64UrlToBytes(key.d), "private", KEM_USAGES));
            }
        });
    }
    _derivePublicKey(k) {
        return new Promise((resolve, reject) => {
            try {
                const pk = x448.getPublicKey(k.key);
                resolve(new XCryptoKey(ALG_NAME, pk, "public"));
            }
            catch (e) {
                reject(e);
            }
        });
    }
    _dh(sk, pk) {
        return new Promise((resolve, reject) => {
            try {
                resolve(x448.getSharedSecret(sk.key, pk.key).buffer);
            }
            catch (e) {
                reject(e);
            }
        });
    }
}