fix: use node.js crypto for x25519 keys

Using node crypto to do X25519 key operations instead of `@noble/curves`
yields a nice little performance bump which translates to slightly lower
latencies when opening connections.

Running the `benchmark.js` file:

Before:

```console
% node ./benchmark.js
Initializing handshake benchmark
Init complete, running benchmark
handshake x 124 ops/sec ±0.47% (84 runs sampled)
```

After:

```console
% node ./benchmark.js
Initializing handshake benchmark
Init complete, running benchmark
handshake x 314 ops/sec ±0.99% (87 runs sampled)
```

package.json

@@ -55,7 +55,6 @@
     "clean": "aegir clean",
     "dep-check": "aegir dep-check",
     "build": "aegir build",
-    "prebuild": "mkdirp dist/src && cp -R src/proto dist/src",
     "lint": "aegir lint",
     "lint:fix": "aegir lint --fix",
     "test": "aegir test",

src/crypto/index.ts

@@ -1,13 +1,17 @@
 import crypto from 'node:crypto'
 import { newInstance, ChaCha20Poly1305 } from '@chainsafe/as-chacha20poly1305'
 import { digest } from '@chainsafe/as-sha256'
+import { concat as uint8ArrayConcat } from 'uint8arrays/concat'
 import { isElectronMain } from 'wherearewe'
 import { pureJsCrypto } from './js.js'
+import type { KeyPair } from '../@types/libp2p.js'
 import type { ICryptoInterface } from '../crypto.js'
 
 const ctx = newInstance()
 const asImpl = new ChaCha20Poly1305(ctx)
 const CHACHA_POLY1305 = 'chacha20-poly1305'
+const PKCS8_PREFIX = Buffer.from([0x30, 0x2e, 0x02, 0x01, 0x00, 0x30, 0x05, 0x06, 0x03, 0x2b, 0x65, 0x6e, 0x04, 0x22, 0x04, 0x20])
+const X25519_PREFIX = Buffer.from([0x30, 0x2a, 0x30, 0x05, 0x06, 0x03, 0x2b, 0x65, 0x6e, 0x03, 0x21, 0x00])
 const nodeCrypto: Pick<ICryptoInterface, 'hashSHA256' | 'chaCha20Poly1305Encrypt' | 'chaCha20Poly1305Decrypt'> = {
   hashSHA256 (data) {
     return crypto.createHash('sha256').update(data).digest()
@@ -76,6 +80,68 @@ export const defaultCrypto: ICryptoInterface = {
       return asCrypto.chaCha20Poly1305Decrypt(ciphertext, nonce, ad, k, dst)
     }
     return nodeCrypto.chaCha20Poly1305Decrypt(ciphertext, nonce, ad, k, dst)
+  },
+  generateX25519KeyPair (): KeyPair {
+    const { publicKey, privateKey } = crypto.generateKeyPairSync('x25519', {
+      publicKeyEncoding: {
+        type: 'spki',
+        format: 'der'
+      },
+      privateKeyEncoding: {
+        type: 'pkcs8',
+        format: 'der'
+      }
+    })
+
+    return {
+      publicKey: publicKey.subarray(X25519_PREFIX.length),
+      privateKey: privateKey.subarray(PKCS8_PREFIX.length)
+    }
+  },
+  generateX25519KeyPairFromSeed (seed: Uint8Array): KeyPair {
+    const privateKey = crypto.createPrivateKey({
+      key: Buffer.concat([
+        PKCS8_PREFIX,
+        seed
+      ], PKCS8_PREFIX.byteLength + seed.byteLength),
+      type: 'pkcs8',
+      format: 'der'
+    })
+
+    const publicKey = crypto.createPublicKey(privateKey)
+      .export({
+        type: 'spki',
+        format: 'der'
+      }).subarray(X25519_PREFIX.length)
+
+    return {
+      publicKey,
+      privateKey: seed
+    }
+  },
+  generateX25519SharedKey (privateKey: Uint8Array, publicKey: Uint8Array): Uint8Array {
+    publicKey = uint8ArrayConcat([
+      X25519_PREFIX,
+      publicKey
+    ], X25519_PREFIX.byteLength + publicKey.byteLength)
+
+    privateKey = uint8ArrayConcat([
+      PKCS8_PREFIX,
+      privateKey
+    ], PKCS8_PREFIX.byteLength + privateKey.byteLength)
+
+    return crypto.diffieHellman({
+      publicKey: crypto.createPublicKey({
+        key: Buffer.from(publicKey, publicKey.byteOffset, publicKey.byteLength),
+        type: 'spki',
+        format: 'der'
+      }),
+      privateKey: crypto.createPrivateKey({
+        key: Buffer.from(privateKey, privateKey.byteOffset, privateKey.byteLength),
+        type: 'pkcs8',
+        format: 'der'
+      })
+    })
   }
 }
 

src/encoder.ts

@@ -1,19 +1,12 @@
+import { alloc as uint8ArrayAlloc, allocUnsafe as uint8ArrayAllocUnsafe } from 'uint8arrays/alloc'
 import { concat as uint8ArrayConcat } from 'uint8arrays/concat'
 import type { bytes } from './@types/basic.js'
 import type { MessageBuffer } from './@types/handshake.js'
 import type { LengthDecoderFunction } from 'it-length-prefixed'
 import type { Uint8ArrayList } from 'uint8arraylist'
 
-const allocUnsafe = (len: number): Uint8Array => {
-  if (globalThis.Buffer) {
-    return globalThis.Buffer.allocUnsafe(len)
-  }
-
-  return new Uint8Array(len)
-}
-
 export const uint16BEEncode = (value: number): Uint8Array => {
-  const target = allocUnsafe(2)
+  const target = uint8ArrayAllocUnsafe(2)
   new DataView(target.buffer, target.byteOffset, target.byteLength).setUint16(0, value, false)
   return target
 }
@@ -52,7 +45,7 @@ export function decode0 (input: bytes): MessageBuffer {
   return {
     ne: input.subarray(0, 32),
     ciphertext: input.subarray(32, input.length),
-    ns: new Uint8Array(0)
+    ns: uint8ArrayAlloc(0)
   }
 }
 
@@ -74,7 +67,7 @@ export function decode2 (input: bytes): MessageBuffer {
   }
 
   return {
-    ne: new Uint8Array(0),
+    ne: uint8ArrayAlloc(0),
     ns: input.subarray(0, 48),
     ciphertext: input.subarray(48, input.length)
   }

src/handshake-xx.ts

@@ -1,4 +1,5 @@
 import { InvalidCryptoExchangeError, UnexpectedPeerError } from '@libp2p/interface/errors'
+import { alloc as uint8ArrayAlloc } from 'uint8arrays/alloc'
 import { decode0, decode1, decode2, encode0, encode1, encode2 } from './encoder.js'
 import { XX } from './handshakes/xx.js'
 import {
@@ -63,7 +64,7 @@ export class XXHandshake implements IHandshake {
     logLocalStaticKeys(this.session.hs.s)
     if (this.isInitiator) {
       logger.trace('Stage 0 - Initiator starting to send first message.')
-      const messageBuffer = this.xx.sendMessage(this.session, new Uint8Array(0))
+      const messageBuffer = this.xx.sendMessage(this.session, uint8ArrayAlloc(0))
       await this.connection.write(encode0(messageBuffer))
       logger.trace('Stage 0 - Initiator finished sending first message.')
       logLocalEphemeralKeys(this.session.hs.e)
@@ -144,13 +145,13 @@ export class XXHandshake implements IHandshake {
   public encrypt (plaintext: Uint8Array, session: NoiseSession): bytes {
     const cs = this.getCS(session)
 
-    return this.xx.encryptWithAd(cs, new Uint8Array(0), plaintext)
+    return this.xx.encryptWithAd(cs, uint8ArrayAlloc(0), plaintext)
   }
 
   public decrypt (ciphertext: Uint8Array, session: NoiseSession, dst?: Uint8Array): { plaintext: bytes, valid: boolean } {
     const cs = this.getCS(session, false)
 
-    return this.xx.decryptWithAd(cs, new Uint8Array(0), ciphertext, dst)
+    return this.xx.decryptWithAd(cs, uint8ArrayAlloc(0), ciphertext, dst)
   }
 
   public getRemoteStaticKey (): bytes {

src/handshakes/abstract-handshake.ts

@@ -1,4 +1,5 @@
 import { fromString as uint8ArrayFromString } from 'uint8arrays'
+import { alloc as uint8ArrayAlloc } from 'uint8arrays/alloc'
 import { concat as uint8ArrayConcat } from 'uint8arrays/concat'
 import { equals as uint8ArrayEquals } from 'uint8arrays/equals'
 import { logger } from '../logger.js'
@@ -44,7 +45,7 @@ export abstract class AbstractHandshake {
   }
 
   protected createEmptyKey (): bytes32 {
-    return new Uint8Array(32)
+    return uint8ArrayAlloc(32)
   }
 
   protected isEmptyKey (k: bytes32): boolean {
@@ -82,7 +83,7 @@ export abstract class AbstractHandshake {
       }
     } else {
       return {
-        plaintext: new Uint8Array(0),
+        plaintext: uint8ArrayAlloc(0),
         valid: false
       }
     }
@@ -112,7 +113,7 @@ export abstract class AbstractHandshake {
     } catch (e) {
       const err = e as Error
       logger.error(err)
-      return new Uint8Array(32)
+      return uint8ArrayAlloc(32)
     }
   }
 
@@ -150,31 +151,31 @@ export abstract class AbstractHandshake {
 
   protected hashProtocolName (protocolName: Uint8Array): bytes32 {
     if (protocolName.length <= 32) {
-      const h = new Uint8Array(32)
+      const h = uint8ArrayAlloc(32)
       h.set(protocolName)
       return h
     } else {
-      return this.getHash(protocolName, new Uint8Array(0))
+      return this.getHash(protocolName, uint8ArrayAlloc(0))
     }
   }
 
   protected split (ss: SymmetricState): SplitState {
-    const [tempk1, tempk2] = this.crypto.getHKDF(ss.ck, new Uint8Array(0))
+    const [tempk1, tempk2] = this.crypto.getHKDF(ss.ck, uint8ArrayAlloc(0))
     const cs1 = this.initializeKey(tempk1)
     const cs2 = this.initializeKey(tempk2)
 
     return { cs1, cs2 }
   }
 
   protected writeMessageRegular (cs: CipherState, payload: bytes): MessageBuffer {
-    const ciphertext = this.encryptWithAd(cs, new Uint8Array(0), payload)
+    const ciphertext = this.encryptWithAd(cs, uint8ArrayAlloc(0), payload)
     const ne = this.createEmptyKey()
-    const ns = new Uint8Array(0)
+    const ns = uint8ArrayAlloc(0)
 
     return { ne, ns, ciphertext }
   }
 
   protected readMessageRegular (cs: CipherState, message: MessageBuffer): DecryptedResult {
-    return this.decryptWithAd(cs, new Uint8Array(0), message.ciphertext)
+    return this.decryptWithAd(cs, uint8ArrayAlloc(0), message.ciphertext)
   }
 }

src/handshakes/xx.ts

@@ -1,3 +1,4 @@
+import { alloc as uint8ArrayAlloc } from 'uint8arrays/alloc'
 import { isValidPublicKey } from '../utils.js'
 import { AbstractHandshake, type DecryptedResult } from './abstract-handshake.js'
 import type { bytes32, bytes } from '../@types/basic.js'
@@ -9,7 +10,7 @@ export class XX extends AbstractHandshake {
     const name = 'Noise_XX_25519_ChaChaPoly_SHA256'
     const ss = this.initializeSymmetric(name)
     this.mixHash(ss, prologue)
-    const re = new Uint8Array(32)
+    const re = uint8ArrayAlloc(32)
 
     return { ss, s, rs, psk, re }
   }
@@ -18,13 +19,13 @@ export class XX extends AbstractHandshake {
     const name = 'Noise_XX_25519_ChaChaPoly_SHA256'
     const ss = this.initializeSymmetric(name)
     this.mixHash(ss, prologue)
-    const re = new Uint8Array(32)
+    const re = uint8ArrayAlloc(32)
 
     return { ss, s, rs, psk, re }
   }
 
   private writeMessageA (hs: HandshakeState, payload: bytes, e?: KeyPair): MessageBuffer {
-    const ns = new Uint8Array(0)
+    const ns = uint8ArrayAlloc(0)
 
     if (e !== undefined) {
       hs.e = e
@@ -113,7 +114,7 @@ export class XX extends AbstractHandshake {
 
   public initSession (initiator: boolean, prologue: bytes32, s: KeyPair): NoiseSession {
     const psk = this.createEmptyKey()
-    const rs = new Uint8Array(32) // no static key yet
+    const rs = uint8ArrayAlloc(32) // no static key yet
     let hs
 
     if (initiator) {
@@ -164,7 +165,7 @@ export class XX extends AbstractHandshake {
   }
 
   public recvMessage (session: NoiseSession, message: MessageBuffer): DecryptedResult {
-    let plaintext: bytes = new Uint8Array(0)
+    let plaintext: bytes = uint8ArrayAlloc(0)
     let valid = false
     if (session.mc === 0) {
       ({ plaintext, valid } = this.readMessageA(session.hs, message))

src/noise.ts

@@ -2,6 +2,7 @@ import { decode } from 'it-length-prefixed'
 import { lpStream, type LengthPrefixedStream } from 'it-length-prefixed-stream'
 import { duplexPair } from 'it-pair/duplex'
 import { pipe } from 'it-pipe'
+import { alloc as uint8ArrayAlloc } from 'uint8arrays/alloc'
 import { NOISE_MSG_MAX_LENGTH_BYTES } from './constants.js'
 import { defaultCrypto } from './crypto/index.js'
 import { decryptStream, encryptStream } from './crypto/streaming.js'
@@ -59,7 +60,7 @@ export class Noise implements INoiseConnection {
     } else {
       this.staticKeys = this.crypto.generateX25519KeyPair()
     }
-    this.prologue = prologueBytes ?? new Uint8Array(0)
+    this.prologue = prologueBytes ?? uint8ArrayAlloc(0)
   }
 
   /**

src/nonce.ts

@@ -1,3 +1,4 @@
+import { alloc as uint8ArrayAlloc } from 'uint8arrays/alloc'
 import type { bytes, uint64 } from './@types/basic.js'
 
 export const MIN_NONCE = 0
@@ -22,7 +23,7 @@ export class Nonce {
 
   constructor (n = MIN_NONCE) {
     this.n = n
-    this.bytes = new Uint8Array(12)
+    this.bytes = uint8ArrayAlloc(12)
     this.view = new DataView(this.bytes.buffer, this.bytes.byteOffset, this.bytes.byteLength)
     this.view.setUint32(4, n, true)
   }