Reduce buffer usage (#521)

This commit is contained in:
Franck R 2022-02-14 10:50:02 +11:00 committed by GitHub
parent 2dc8764be2
commit cfc5eee4ff
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
19 changed files with 165 additions and 80 deletions

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@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
- docs: Various improvements.
- Ran `npm audit fix`.
- `Waku.dial` accepts protocols expected from the peer. Defaults to Waku Relay only.
- Deprecated `hexToBuf` & `bufToHex` in favour of `hexToBytes` & `bytesToHex` to move towards removing the `buffer` polyfill.
### Removed

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@ -1,7 +1,7 @@
import "@ethersproject/shims";
import { PublicKeyMessage } from "./messaging/wire";
import { hexToBuf, equalByteArrays, bufToHex } from "js-waku/lib/utils";
import { hexToBytes, equalByteArrays, bytesToHex } from "js-waku/lib/utils";
import * as sigUtil from "eth-sig-util";
/**
@ -28,8 +28,8 @@ export async function createPublicKeyMessage(
return new PublicKeyMessage({
encryptionPublicKey: encryptionPublicKey,
ethAddress: hexToBuf(address),
signature: hexToBuf(signature),
ethAddress: hexToBytes(address),
signature: hexToBytes(signature),
});
}
@ -41,7 +41,7 @@ function buildMsgParams(encryptionPublicKey: Uint8Array, fromAddress: string) {
version: "1",
},
message: {
encryptionPublicKey: bufToHex(encryptionPublicKey),
encryptionPublicKey: bytesToHex(encryptionPublicKey),
ownerAddress: fromAddress,
},
// Refers to the keys of the *types* object below.
@ -79,7 +79,7 @@ export async function signEncryptionKey(
console.log("TYPED SIGNED:" + JSON.stringify(result));
return hexToBuf(result);
return hexToBytes(result);
}
/**
@ -88,13 +88,13 @@ export async function signEncryptionKey(
export function validatePublicKeyMessage(msg: PublicKeyMessage): boolean {
const recovered = sigUtil.recoverTypedSignature_v4({
data: JSON.parse(
buildMsgParams(msg.encryptionPublicKey, "0x" + bufToHex(msg.ethAddress))
buildMsgParams(msg.encryptionPublicKey, "0x" + bytesToHex(msg.ethAddress))
),
sig: "0x" + bufToHex(msg.signature),
sig: "0x" + bytesToHex(msg.signature),
});
console.log("Recovered", recovered);
console.log("ethAddress", "0x" + bufToHex(msg.ethAddress));
console.log("ethAddress", "0x" + bytesToHex(msg.ethAddress));
return equalByteArrays(recovered, msg.ethAddress);
}

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@ -8,7 +8,7 @@ import {
} from "@material-ui/core";
import React, { ChangeEvent, useState, KeyboardEvent } from "react";
import { Waku, WakuMessage } from "js-waku";
import { bufToHex, hexToBuf } from "js-waku/lib/utils";
import { bytesToHex, hexToBytes } from "js-waku/lib/utils";
import { PrivateMessage } from "./wire";
import { PrivateMessageContentTopic } from "../waku";
import * as sigUtil from "eth-sig-util";
@ -111,7 +111,7 @@ async function encodeEncryptedWakuMessage(
address: string
): Promise<WakuMessage> {
const privateMessage = new PrivateMessage({
toAddress: hexToBuf(address),
toAddress: hexToBytes(address),
message: message,
});
@ -119,7 +119,7 @@ async function encodeEncryptedWakuMessage(
const encObj = sigUtil.encrypt(
Buffer.from(publicKey).toString("base64"),
{ data: bufToHex(payload) },
{ data: bytesToHex(payload) },
"x25519-xsalsa20-poly1305"
);

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@ -3,7 +3,7 @@ import { Waku, WakuMessage } from "js-waku";
import { PrivateMessage, PublicKeyMessage } from "./messaging/wire";
import { validatePublicKeyMessage } from "./crypto";
import { Message } from "./messaging/Messages";
import { bufToHex, equalByteArrays } from "js-waku/lib/utils";
import { bytesToHex, equalByteArrays } from "js-waku/lib/utils";
export const PublicKeyContentTopic =
"/eth-pm-wallet/1/encryption-public-key/proto";
@ -44,7 +44,7 @@ export function handlePublicKeyMessage(
if (res) {
setPublicKeys((prevPks: Map<string, Uint8Array>) => {
prevPks.set(
bufToHex(publicKeyMsg.ethAddress),
bytesToHex(publicKeyMsg.ethAddress),
publicKeyMsg.encryptionPublicKey
);
return new Map(prevPks);

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@ -1,13 +1,13 @@
import "@ethersproject/shims";
import { PublicKeyMessage } from "./messaging/wire";
import { hexToBuf, equalByteArrays, bufToHex } from "js-waku/lib/utils";
import { hexToBytes, equalByteArrays, bytesToHex } from "js-waku/lib/utils";
import { generatePrivateKey, getPublicKey } from "js-waku";
import * as sigUtil from "eth-sig-util";
import { PublicKeyContentTopic } from "./waku";
import { keccak256 } from "ethers/lib/utils";
export const PublicKeyMessageEncryptionKey = hexToBuf(
export const PublicKeyMessageEncryptionKey = hexToBytes(
keccak256(Buffer.from(PublicKeyContentTopic, "utf-8"))
);
@ -49,8 +49,8 @@ export async function createPublicKeyMessage(
return new PublicKeyMessage({
encryptionPublicKey: encryptionPublicKey,
ethAddress: hexToBuf(address),
signature: hexToBuf(signature),
ethAddress: hexToBytes(address),
signature: hexToBytes(signature),
});
}
@ -62,7 +62,7 @@ function buildMsgParams(encryptionPublicKey: Uint8Array, fromAddress: string) {
version: "1",
},
message: {
encryptionPublicKey: bufToHex(encryptionPublicKey),
encryptionPublicKey: bytesToHex(encryptionPublicKey),
ownerAddress: fromAddress,
},
// Refers to the keys of the *types* object below.
@ -100,7 +100,7 @@ export async function signEncryptionKey(
console.log("TYPED SIGNED:" + JSON.stringify(result));
return hexToBuf(result);
return hexToBytes(result);
}
/**
@ -109,13 +109,13 @@ export async function signEncryptionKey(
export function validatePublicKeyMessage(msg: PublicKeyMessage): boolean {
const recovered = sigUtil.recoverTypedSignature_v4({
data: JSON.parse(
buildMsgParams(msg.encryptionPublicKey, "0x" + bufToHex(msg.ethAddress))
buildMsgParams(msg.encryptionPublicKey, "0x" + bytesToHex(msg.ethAddress))
),
sig: "0x" + bufToHex(msg.signature),
sig: "0x" + bytesToHex(msg.signature),
});
console.log("Recovered", recovered);
console.log("ethAddress", "0x" + bufToHex(msg.ethAddress));
console.log("ethAddress", "0x" + bytesToHex(msg.ethAddress));
return equalByteArrays(recovered, msg.ethAddress);
}

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@ -1,5 +1,5 @@
import { KeyPair } from "../crypto";
import { bufToHex, hexToBuf } from "js-waku/lib/utils";
import { bytesToHex, hexToBytes } from "js-waku/lib/utils";
/**
* Save keypair to storage, encrypted with password
@ -11,9 +11,9 @@ export async function saveKeyPairToStorage(
const { salt, iv, cipher } = await encryptKey(EncryptionKeyPair, password);
const data = {
salt: bufToHex(salt),
iv: bufToHex(iv),
cipher: bufToHex(cipher),
salt: bytesToHex(salt),
iv: bytesToHex(iv),
cipher: bytesToHex(cipher),
};
localStorage.setItem("cipherEncryptionKeyPair", JSON.stringify(data));
@ -29,9 +29,9 @@ export async function loadKeyPairFromStorage(
if (!str) return;
const data = JSON.parse(str);
const salt = hexToBuf(data.salt);
const iv = hexToBuf(data.iv);
const cipher = hexToBuf(data.cipher);
const salt = hexToBytes(data.salt);
const iv = hexToBytes(data.iv);
const cipher = hexToBytes(data.cipher);
return await decryptKey(salt, iv, cipher, password);
}
@ -96,9 +96,9 @@ async function encryptKey(encryptionKeyPair: KeyPair, password: string) {
* Derive a key from a password, and use the key to decrypt the cipher key pair.
*/
async function decryptKey(
salt: Buffer,
iv: Buffer,
cipherKeyPair: Buffer,
salt: Uint8Array,
iv: Uint8Array,
cipherKeyPair: Uint8Array,
password: string
): Promise<KeyPair | undefined> {
const keyMaterial = await getKeyMaterial(password);

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@ -8,7 +8,7 @@ import {
} from "@material-ui/core";
import React, { ChangeEvent, useState, KeyboardEvent } from "react";
import { Waku, WakuMessage } from "js-waku";
import { hexToBuf } from "js-waku/lib/utils";
import { hexToBytes } from "js-waku/lib/utils";
import { PrivateMessage } from "./wire";
import { PrivateMessageContentTopic } from "../waku";
@ -110,7 +110,7 @@ async function encodeEncryptedWakuMessage(
address: string
): Promise<WakuMessage> {
const privateMessage = new PrivateMessage({
toAddress: hexToBuf(address),
toAddress: hexToBytes(address),
message: message,
});

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@ -3,7 +3,7 @@ import { Waku, WakuMessage } from "js-waku";
import { PrivateMessage, PublicKeyMessage } from "./messaging/wire";
import { validatePublicKeyMessage } from "./crypto";
import { Message } from "./messaging/Messages";
import { bufToHex, equalByteArrays } from "js-waku/lib/utils";
import { bytesToHex, equalByteArrays } from "js-waku/lib/utils";
export const PublicKeyContentTopic = "/eth-pm/1/public-key/proto";
export const PrivateMessageContentTopic = "/eth-pm/1/private-message/proto";
@ -42,7 +42,7 @@ export function handlePublicKeyMessage(
if (res) {
setter((prevPks: Map<string, Uint8Array>) => {
prevPks.set(
bufToHex(publicKeyMsg.ethAddress),
bytesToHex(publicKeyMsg.ethAddress),
publicKeyMsg.encryptionPublicKey
);
return new Map(prevPks);

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@ -1,4 +1,4 @@
import { bufToHex } from "../utils";
import { bytesToHex } from "../utils";
import { NodeId } from "./types";
@ -6,5 +6,5 @@ export function createNodeId(buffer: Buffer): NodeId {
if (buffer.length !== 32) {
throw new Error("NodeId must be 32 bytes in length");
}
return bufToHex(buffer);
return bytesToHex(buffer);
}

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@ -2,7 +2,7 @@ import { assert, expect } from "chai";
import { Multiaddr } from "multiaddr";
import PeerId from "peer-id";
import { bufToHex } from "../utils";
import { bytesToHex } from "../utils";
import { ERR_INVALID_ID } from "./constants";
import { ENR } from "./enr";
@ -31,8 +31,8 @@ describe("ENR", function () {
const txt = enr.encodeTxt(keypair.privateKey);
expect(txt.slice(0, 4)).to.be.equal("enr:");
const enr2 = ENR.decodeTxt(txt);
expect(bufToHex(enr2.signature as Buffer)).to.be.equal(
bufToHex(enr.signature as Buffer)
expect(bytesToHex(enr2.signature as Buffer)).to.be.equal(
bytesToHex(enr.signature as Buffer)
);
const multiaddr = enr2.getLocationMultiaddr("udp")!;
expect(multiaddr.toString()).to.be.equal("/ip4/18.223.219.100/udp/9000");
@ -56,7 +56,7 @@ describe("ENR", function () {
const enr = ENR.decodeTxt(txt);
const eth2 = enr.get("eth2") as Buffer;
expect(eth2).to.not.be.undefined;
expect(bufToHex(eth2)).to.be.equal("f6775d0700000113ffffffffffff1f00");
expect(bytesToHex(eth2)).to.be.equal("f6775d0700000113ffffffffffff1f00");
});
it("should decode valid ENR with multiaddrs successfully [shared test vector]", () => {

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@ -2,6 +2,8 @@ import { keccak256, Message } from "js-sha3";
/**
* Convert input to a Buffer.
*
* @deprecated Use `hexToBytes` instead.
*/
export function hexToBuf(hex: string | Buffer | Uint8Array): Buffer {
if (typeof hex === "string") {
@ -11,36 +13,66 @@ export function hexToBuf(hex: string | Buffer | Uint8Array): Buffer {
}
}
/**
* Convert input to a byte array.
*/
export function hexToBytes(hex: string | Uint8Array): Uint8Array {
if (typeof hex === "string") {
const _hex = hex.replace(/^0x/i, "");
const bytes = [];
for (let c = 0; c < _hex.length; c += 2)
bytes.push(parseInt(_hex.substring(c, c + 2), 16));
return new Uint8Array(bytes);
}
return hex;
}
/**
* Convert input to hex string (no `0x` prefix).
*
* @deprecated Use `bytesToHex` instead.
*/
export function bufToHex(buf: Uint8Array | Buffer | ArrayBuffer): string {
const _buf = Buffer.from(buf);
return _buf.toString("hex");
}
/**
* Convert byte array to hex string (no `0x` prefix).
*/
export function bytesToHex(bytes: Uint8Array): string {
const hex = [];
for (let i = 0; i < bytes.length; i++) {
const current = bytes[i] < 0 ? bytes[i] + 256 : bytes[i];
hex.push((current >>> 4).toString(16));
hex.push((current & 0xf).toString(16));
}
return hex.join("");
}
/**
* Compare both inputs, return true if they represent the same byte array.
*/
export function equalByteArrays(
a: Uint8Array | Buffer | string,
b: Uint8Array | Buffer | string
a: Uint8Array | string,
b: Uint8Array | string
): boolean {
let aBuf: Buffer;
let bBuf: Buffer;
let _a: string;
let _b: string;
if (typeof a === "string") {
aBuf = hexToBuf(a);
_a = a.replace(/^0x/i, "").toLowerCase();
} else {
aBuf = Buffer.from(a);
_a = bytesToHex(a);
}
if (typeof b === "string") {
bBuf = hexToBuf(b);
_b = b.replace(/^0x/i, "").toLowerCase();
} else {
bBuf = Buffer.from(b);
_b = bytesToHex(b);
}
return aBuf.compare(bBuf) === 0;
return _a === _b;
}
/**

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@ -2,13 +2,14 @@ import { expect } from "chai";
import debug from "debug";
import {
bytesToUtf8,
makeLogFileName,
NimWaku,
NOISE_KEY_1,
WakuRelayMessage,
} from "../../test_utils";
import { delay } from "../../test_utils/delay";
import { hexToBuf } from "../utils";
import { hexToBytes } from "../utils";
import { Protocols, Waku } from "../waku";
import {
@ -90,8 +91,8 @@ describe("Waku Message [node only]", function () {
dbg("Ask nim-waku to generate asymmetric key pair");
const keyPair = await nimWaku.getAsymmetricKeyPair();
const privateKey = hexToBuf(keyPair.privateKey);
const publicKey = hexToBuf(keyPair.publicKey);
const privateKey = hexToBytes(keyPair.privateKey);
const publicKey = hexToBytes(keyPair.publicKey);
const messageText = "This is a message I am going to encrypt";
dbg("Encrypt message");
@ -116,7 +117,7 @@ describe("Waku Message [node only]", function () {
dbg("Check message content");
expect(msgs[0].contentTopic).to.equal(message.contentTopic);
expect(hexToBuf(msgs[0].payload).toString("utf-8")).to.equal(messageText);
expect(bytesToUtf8(hexToBytes(msgs[0].payload))).to.equal(messageText);
});
it("JS decrypts nim message [symmetric, no signature]", async function () {
@ -177,7 +178,7 @@ describe("Waku Message [node only]", function () {
}
expect(msgs[0].contentTopic).to.equal(message.contentTopic);
expect(hexToBuf(msgs[0].payload).toString("utf-8")).to.equal(messageText);
expect(bytesToUtf8(hexToBytes(msgs[0].payload))).to.equal(messageText);
});
});
});

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@ -5,7 +5,7 @@ import * as ecies from "ecies-geth";
import { keccak256 } from "js-sha3";
import * as secp256k1 from "secp256k1";
import { hexToBuf } from "../utils";
import { hexToBytes } from "../utils";
import { IvSize, symmetric, SymmetricKeySize } from "./symmetric";
@ -58,7 +58,7 @@ export function clearEncode(
if (sigPrivKey) {
envelope[0] |= IsSignedMask;
const hash = keccak256(envelope);
const s = secp256k1.ecdsaSign(hexToBuf(hash), sigPrivKey);
const s = secp256k1.ecdsaSign(hexToBytes(hash), sigPrivKey);
envelope = Buffer.concat([envelope, s.signature, Buffer.from([s.recid])]);
sig = {
signature: Buffer.from(s.signature),
@ -116,7 +116,7 @@ export async function encryptAsymmetric(
data: Uint8Array | Buffer,
publicKey: Uint8Array | Buffer | string
): Promise<Uint8Array> {
return ecies.encrypt(hexToBuf(publicKey), Buffer.from(data));
return ecies.encrypt(Buffer.from(hexToBytes(publicKey)), Buffer.from(data));
}
/**
@ -148,7 +148,11 @@ export async function encryptSymmetric(
const iv = symmetric.generateIv();
// Returns `cipher | tag`
const cipher = await symmetric.encrypt(iv, hexToBuf(key), Buffer.from(data));
const cipher = await symmetric.encrypt(
iv,
Buffer.from(hexToBytes(key)),
Buffer.from(data)
);
return Buffer.concat([cipher, Buffer.from(iv)]);
}
@ -170,7 +174,7 @@ export async function decryptSymmetric(
const cipher = data.slice(0, ivStart);
const iv = data.slice(ivStart);
return symmetric.decrypt(iv, hexToBuf(key), cipher);
return symmetric.decrypt(iv, Buffer.from(hexToBytes(key)), cipher);
}
/**
@ -250,7 +254,7 @@ function ecRecoverPubKey(messageHash: string, signature: Buffer): Uint8Array {
return secp256k1.ecdsaRecover(
signature.slice(0, 64),
recovery,
hexToBuf(messageHash),
hexToBytes(messageHash),
false
);
}

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@ -13,7 +13,7 @@ import { InMessage } from "libp2p-interfaces/src/pubsub";
import { SignaturePolicy } from "libp2p-interfaces/src/pubsub/signature-policy";
import PeerId from "peer-id";
import { hexToBuf } from "../utils";
import { hexToBytes } from "../utils";
import { CreateOptions, DefaultPubSubTopic } from "../waku";
import { DecryptionMethod, WakuMessage } from "../waku_message";
@ -135,7 +135,7 @@ export class WakuRelay extends Gossipsub {
key: Uint8Array | string,
options?: { method?: DecryptionMethod; contentTopics?: string[] }
): void {
this.decryptionKeys.set(hexToBuf(key), options ?? {});
this.decryptionKeys.set(hexToBytes(key), options ?? {});
}
/**
@ -145,7 +145,7 @@ export class WakuRelay extends Gossipsub {
* Strings must be in hex format.
*/
deleteDecryptionKey(key: Uint8Array | string): void {
this.decryptionKeys.delete(hexToBuf(key));
this.decryptionKeys.delete(hexToBytes(key));
}
/**

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@ -8,7 +8,7 @@ import PeerId from "peer-id";
import { HistoryResponse_Error } from "../../proto";
import { getPeersForProtocol, selectRandomPeer } from "../select_peer";
import { hexToBuf } from "../utils";
import { hexToBytes } from "../utils";
import { DefaultPubSubTopic } from "../waku";
import { DecryptionMethod, WakuMessage } from "../waku_message";
@ -181,7 +181,7 @@ export class WakuStore {
if (opts.decryptionKeys) {
opts.decryptionKeys.forEach((key) => {
decryptionKeys.push({
key: hexToBuf(key),
key: hexToBytes(key),
contentTopics: contentTopics.length ? contentTopics : undefined,
method: undefined,
});
@ -276,7 +276,7 @@ export class WakuStore {
key: Uint8Array | string,
options?: { method?: DecryptionMethod; contentTopics?: string[] }
): void {
this.decryptionKeys.set(hexToBuf(key), options ?? {});
this.decryptionKeys.set(hexToBytes(key), options ?? {});
}
/**
@ -286,7 +286,7 @@ export class WakuStore {
* Strings must be in hex format.
*/
deleteDecryptionKey(key: Uint8Array | string): void {
this.decryptionKeys.delete(hexToBuf(key));
this.decryptionKeys.delete(hexToBytes(key));
}
/**

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@ -9,3 +9,4 @@ export * from "./async_fs";
export * from "./constants";
export * from "./log_file";
export * from "./nim_waku";
export * from "./utf8";

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@ -1,6 +1,6 @@
import { expect } from "chai";
import { argsToArray, bufToHex, defaultArgs, strToHex } from "./nim_waku";
import { argsToArray, bytesToHex, defaultArgs, strToHex } from "./nim_waku";
describe("nim_waku", () => {
it("Correctly serialized arguments", function () {
@ -37,7 +37,7 @@ describe("nim_waku", () => {
]);
const expected = "5468697320697320616e207574662d3820737472696e672e";
const actual = bufToHex(buf);
const actual = bytesToHex(buf);
expect(actual).to.deep.equal(expected);
});
});

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@ -11,7 +11,7 @@ import { Multiaddr, multiaddr } from "multiaddr";
import PeerId from "peer-id";
import portfinder from "portfinder";
import { hexToBuf } from "../lib/utils";
import { hexToBytes } from "../lib/utils";
import { DefaultPubSubTopic } from "../lib/waku";
import { WakuMessage } from "../lib/waku_message";
import * as proto from "../proto/waku/v2/message";
@ -203,7 +203,7 @@ export class NimWaku {
}
const rpcMessage = {
payload: bufToHex(message.payload),
payload: bytesToHex(message.payload),
contentTopic: message.contentTopic,
timestamp,
};
@ -258,7 +258,7 @@ export class NimWaku {
return this.rpcCall<boolean>("post_waku_v2_private_v1_asymmetric_message", [
pubSubTopic ? pubSubTopic : DefaultPubSubTopic,
message,
"0x" + bufToHex(publicKey),
"0x" + bytesToHex(publicKey),
]);
}
@ -272,18 +272,18 @@ export class NimWaku {
"get_waku_v2_private_v1_asymmetric_messages",
[
pubSubTopic ? pubSubTopic : DefaultPubSubTopic,
"0x" + bufToHex(privateKey),
"0x" + bytesToHex(privateKey),
]
);
}
async getSymmetricKey(): Promise<Buffer> {
async getSymmetricKey(): Promise<Uint8Array> {
this.checkProcess();
return this.rpcCall<string>(
"get_waku_v2_private_v1_symmetric_key",
[]
).then(hexToBuf);
).then(hexToBytes);
}
async postSymmetricMessage(
@ -300,7 +300,7 @@ export class NimWaku {
return this.rpcCall<boolean>("post_waku_v2_private_v1_symmetric_message", [
pubSubTopic ? pubSubTopic : DefaultPubSubTopic,
message,
"0x" + bufToHex(symKey),
"0x" + bytesToHex(symKey),
]);
}
@ -312,7 +312,10 @@ export class NimWaku {
return await this.rpcCall<WakuRelayMessage[]>(
"get_waku_v2_private_v1_symmetric_messages",
[pubSubTopic ? pubSubTopic : DefaultPubSubTopic, "0x" + bufToHex(symKey)]
[
pubSubTopic ? pubSubTopic : DefaultPubSubTopic,
"0x" + bytesToHex(symKey),
]
);
}
@ -416,7 +419,7 @@ export function strToHex(str: string): string {
return hex;
}
export function bufToHex(buffer: Uint8Array): string {
export function bytesToHex(buffer: Uint8Array): string {
return Array.prototype.map
.call(buffer, (x) => ("00" + x.toString(16)).slice(-2))
.join("");

43
src/test_utils/utf8.ts Normal file
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@ -0,0 +1,43 @@
// Thanks https://gist.github.com/pascaldekloe/62546103a1576803dade9269ccf76330
export function bytesToUtf8(bytes: Uint8Array): string {
let i = 0,
s = "";
while (i < bytes.length) {
let c = bytes[i++];
if (c > 127) {
if (c > 191 && c < 224) {
if (i >= bytes.length)
throw new Error("UTF-8 decode: incomplete 2-byte sequence");
c = ((c & 31) << 6) | (bytes[i++] & 63);
} else if (c > 223 && c < 240) {
if (i + 1 >= bytes.length)
throw new Error("UTF-8 decode: incomplete 3-byte sequence");
c = ((c & 15) << 12) | ((bytes[i++] & 63) << 6) | (bytes[i++] & 63);
} else if (c > 239 && c < 248) {
if (i + 2 >= bytes.length)
throw new Error("UTF-8 decode: incomplete 4-byte sequence");
c =
((c & 7) << 18) |
((bytes[i++] & 63) << 12) |
((bytes[i++] & 63) << 6) |
(bytes[i++] & 63);
} else
throw new Error(
"UTF-8 decode: unknown multi byte start 0x" +
c.toString(16) +
" at index " +
(i - 1)
);
}
if (c <= 0xffff) s += String.fromCharCode(c);
else if (c <= 0x10ffff) {
c -= 0x10000;
s += String.fromCharCode((c >> 10) | 0xd800);
s += String.fromCharCode((c & 0x3ff) | 0xdc00);
} else
throw new Error(
"UTF-8 decode: code point 0x" + c.toString(16) + " exceeds UTF-16 reach"
);
}
return s;
}