feat: load or create key

server/src/utils/crypto.ts

@@ -1,3 +1,4 @@
+import fs from 'fs'
 import { generateKeyPairSync } from 'crypto'
 
 type KeyPair = {
@@ -5,8 +6,26 @@ type KeyPair = {
   publicKey: string
 }
 
+export function loadOrCreateKeyPair(privateKeyPath: string): KeyPair {
+  const publicKeyPath = `${privateKeyPath}.pub`
+  if (fs.existsSync(privateKeyPath) && fs.existsSync(publicKeyPath)) {
+    const privateKey = fs.readFileSync(privateKeyPath, 'utf8')
+    const publicKey = fs.readFileSync(publicKeyPath, 'utf8')
+    return { privateKey, publicKey }
+  }
+  const keyPair = generateKeyPair()
+  fs.writeFileSync(privateKeyPath, keyPair.privateKey, {
+    mode: 0o600,
+  })
+  fs.writeFileSync(publicKeyPath, keyPair.publicKey, {
+    mode: 0o600,
+  })
+  return keyPair
+}
+
 export function generateKeyPair(): KeyPair {
-  const { privateKey, publicKey } = generateKeyPairSync('ed25519', {
+  const { privateKey, publicKey } = generateKeyPairSync('rsa', {
+    modulusLength: 2048,
     publicKeyEncoding: {
       type: 'spki',
       format: 'pem',