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import {
bytesToString,
canonicalJson,
decodeCrock,
encodeCrock,
getRandomBytes,
kdf,
secretbox,
stringToBytes,
} from "@gnu-taler/taler-util";
import { argon2id } from "hash-wasm";
export type Flavor<T, FlavorT> = T & { _flavor?: FlavorT };
export type FlavorP<T, FlavorT, S extends number> = T & {
_flavor?: FlavorT;
_size?: S;
};
export type UserIdentifier = Flavor<string, "UserIdentifier">;
export type ServerSalt = Flavor<string, "ServerSalt">;
export type PolicySalt = Flavor<string, "PolicySalt">;
export type PolicyKey = FlavorP<string, "PolicyKey", 64>;
export type KeyShare = Flavor<string, "KeyShare">;
export type EncryptedKeyShare = Flavor<string, "EncryptedKeyShare">;
export type EncryptedTruth = Flavor<string, "EncryptedTruth">;
export type EncryptedCoreSecret = Flavor<string, "EncryptedCoreSecret">;
export type EncryptedMasterKey = Flavor<string, "EncryptedMasterKey">;
/**
* Truth key, found in the recovery document.
*/
export type TruthKey = Flavor<string, "TruthKey">;
export type EncryptionNonce = Flavor<string, "EncryptionNonce">;
export type OpaqueData = Flavor<string, "OpaqueData">;
const nonceSize = 24;
const masterKeySize = 64;
export async function userIdentifierDerive(
idData: any,
serverSalt: ServerSalt,
): Promise<UserIdentifier> {
const canonIdData = canonicalJson(idData);
const hashInput = stringToBytes(canonIdData);
const result = await argon2id({
hashLength: 64,
iterations: 3,
memorySize: 1024 /* kibibytes */,
parallelism: 1,
password: hashInput,
salt: decodeCrock(serverSalt),
outputType: "binary",
});
return encodeCrock(result);
}
function taConcat(chunks: Uint8Array[]): Uint8Array {
let payloadLen = 0;
for (const c of chunks) {
payloadLen += c.byteLength;
}
const buf = new ArrayBuffer(payloadLen);
const u8buf = new Uint8Array(buf);
let p = 0;
for (const c of chunks) {
u8buf.set(c, p);
p += c.byteLength;
}
return u8buf;
}
export async function policyKeyDerive(
keyShares: KeyShare[],
policySalt: PolicySalt,
): Promise<PolicyKey> {
const chunks = keyShares.map((x) => decodeCrock(x));
const polKey = kdf(
64,
taConcat(chunks),
decodeCrock(policySalt),
new Uint8Array(0),
);
return encodeCrock(polKey);
}
async function deriveKey(
keySeed: OpaqueData,
nonce: EncryptionNonce,
salt: string,
): Promise<Uint8Array> {
return kdf(32, decodeCrock(keySeed), stringToBytes(salt), decodeCrock(nonce));
}
async function anastasisEncrypt(
nonce: EncryptionNonce,
keySeed: OpaqueData,
plaintext: OpaqueData,
salt: string,
): Promise<OpaqueData> {
const key = await deriveKey(keySeed, nonce, salt);
const nonceBuf = decodeCrock(nonce);
const cipherText = secretbox(decodeCrock(plaintext), decodeCrock(nonce), key);
return encodeCrock(taConcat([nonceBuf, cipherText]));
}
const asOpaque = (x: string): OpaqueData => x;
const asEncryptedKeyShare = (x: OpaqueData): EncryptedKeyShare => x as string;
const asEncryptedTruth = (x: OpaqueData): EncryptedTruth => x as string;
export async function encryptKeyshare(
keyShare: KeyShare,
userId: UserIdentifier,
answerSalt?: string,
): Promise<EncryptedKeyShare> {
const s = answerSalt ?? "eks";
const nonce = encodeCrock(getRandomBytes(24));
return asEncryptedKeyShare(
await anastasisEncrypt(nonce, asOpaque(userId), asOpaque(keyShare), s),
);
}
export async function encryptTruth(
nonce: EncryptionNonce,
truthEncKey: TruthKey,
truth: OpaqueData,
): Promise<EncryptedTruth> {
const salt = "ect";
return asEncryptedTruth(
await anastasisEncrypt(nonce, asOpaque(truthEncKey), truth, salt),
);
}
export interface CoreSecretEncResult {
encCoreSecret: EncryptedCoreSecret;
encMasterKeys: EncryptedMasterKey[];
}
export async function coreSecretEncrypt(
policyKeys: PolicyKey[],
coreSecret: OpaqueData,
): Promise<CoreSecretEncResult> {
const masterKey = getRandomBytes(masterKeySize);
const nonce = encodeCrock(getRandomBytes(nonceSize));
const coreSecretEncSalt = "cse";
const masterKeyEncSalt = "emk";
const encCoreSecret = (await anastasisEncrypt(
nonce,
encodeCrock(masterKey),
coreSecret,
coreSecretEncSalt,
)) as string;
const encMasterKeys: EncryptedMasterKey[] = [];
for (let i = 0; i < policyKeys.length; i++) {
const polNonce = encodeCrock(getRandomBytes(nonceSize));
const encMasterKey = await anastasisEncrypt(
polNonce,
asOpaque(policyKeys[i]),
encodeCrock(masterKey),
masterKeyEncSalt,
);
encMasterKeys.push(encMasterKey as string);
}
return {
encCoreSecret,
encMasterKeys,
};
}
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