did-jwt/lib.esm/encryption/X25519-ECDH-1PU.js

Library for Signing and Verifying JWTs that use DIDs as issuers and JWEs that use DIDs as recipients

import { base64ToBytes, bytesToBase64url, generateKeyPair, generateKeyPairFromSeed } from '../util.js';
import { concatKDF } from '../Digest.js';
import { x25519 } from '@noble/curves/ed25519.js';
export async function computeX25519Ecdh1PUv3Kek(recipient, recipientSecret, senderPublicKey, alg) {
    const crv = 'X25519';
    const keyLen = 256;
    const header = recipient.header;
    if (header.epk?.crv !== crv || typeof header.epk.x == 'undefined')
        return null;
    // ECDH-1PU requires additional shared secret between
    // static key of sender and static key of recipient
    const publicKey = base64ToBytes(header.epk.x);
    let zE;
    let zS;
    if (recipientSecret instanceof Uint8Array) {
        zE = x25519.getSharedSecret(recipientSecret, publicKey);
        zS = x25519.getSharedSecret(recipientSecret, senderPublicKey);
    }
    else {
        zE = await recipientSecret(publicKey);
        zS = await recipientSecret(senderPublicKey);
    }
    const sharedSecret = new Uint8Array(zE.length + zS.length);
    sharedSecret.set(zE);
    sharedSecret.set(zS, zE.length);
    // Key Encryption Key
    let producerInfo;
    let consumerInfo;
    if (recipient.header.apu)
        producerInfo = base64ToBytes(recipient.header.apu);
    if (recipient.header.apv)
        consumerInfo = base64ToBytes(recipient.header.apv);
    return concatKDF(sharedSecret, keyLen, alg, producerInfo, consumerInfo);
}
export async function createX25519Ecdh1PUv3Kek(recipientPublicKey, senderSecret, alg, // must be provided as this is the key agreement alg + the key wrapper alg, Example: 'ECDH-ES+A256KW'
apu, apv, ephemeralKeyPair) {
    const crv = 'X25519';
    const keyLen = 256;
    const ephemeral = ephemeralKeyPair ? generateKeyPairFromSeed(ephemeralKeyPair.secretKey) : generateKeyPair();
    const epk = { kty: 'OKP', crv, x: bytesToBase64url(ephemeral.publicKey) };
    const zE = x25519.getSharedSecret(ephemeral.secretKey, recipientPublicKey);
    // ECDH-1PU requires additional shared secret between
    // static key of sender and static key of recipient
    let zS;
    if (senderSecret instanceof Uint8Array) {
        zS = x25519.getSharedSecret(senderSecret, recipientPublicKey);
    }
    else {
        zS = await senderSecret(recipientPublicKey);
    }
    const sharedSecret = new Uint8Array(zE.length + zS.length);
    sharedSecret.set(zE);
    sharedSecret.set(zS, zE.length);
    let partyUInfo = new Uint8Array(0);
    let partyVInfo = new Uint8Array(0);
    if (apu)
        partyUInfo = base64ToBytes(apu);
    if (apv)
        partyVInfo = base64ToBytes(apv);
    // Key Encryption Key
    const kek = concatKDF(sharedSecret, keyLen, alg, partyUInfo, partyVInfo);
    return { epk, kek };
}
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