ts-mls/dist/src/crypto/kdf.js

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import { utf8ToBytes } from "@noble/ciphers/utils";
import { HkdfSha256, HkdfSha384, HkdfSha512 } from "@hpke/core";
import { encodeVarLenData } from "../codec/variableLength";
import { encodeUint16, encodeUint32 } from "../codec/number";
import { bytesToBuffer } from "../util/byteArray";
export function makeKdfImpl(k) {
    return {
        async extract(salt, ikm) {
            const result = await k.extract(bytesToBuffer(salt), bytesToBuffer(ikm));
            return new Uint8Array(result);
        },
        async expand(prk, info, len) {
            const result = await k.expand(bytesToBuffer(prk), bytesToBuffer(info), len);
            return new Uint8Array(result);
        },
        size: k.hashSize,
    };
}
export function makeKdf(kdfAlg) {
    switch (kdfAlg) {
        case "HKDF-SHA256":
            return new HkdfSha256();
        case "HKDF-SHA384":
            return new HkdfSha384();
        case "HKDF-SHA512":
            return new HkdfSha512();
    }
}
export function expandWithLabel(secret, label, context, length, kdf) {
    return kdf.expand(secret, new Uint8Array([
        ...encodeUint16(length),
        ...encodeVarLenData(utf8ToBytes(`MLS 1.0 ${label}`)),
        ...encodeVarLenData(context),
    ]), length);
}
export async function deriveSecret(secret, label, kdf) {
    return expandWithLabel(secret, label, new Uint8Array(), kdf.size, kdf);
}
export async function deriveTreeSecret(secret, label, generation, length, kdf) {
    return expandWithLabel(secret, label, encodeUint32(generation), length, kdf);
}
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