fix: use CreateKeyPair instead of ImportKeyPair for simpler SSH key management

AWS CreateKeyPair generates the RSA key pair server-side and returns the private key,
avoiding the need to manually format RSA public keys in OpenSSH wire format.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/services/ec2.ts

@@ -7,12 +7,11 @@ import {
   DeleteSecurityGroupCommand,
   AuthorizeSecurityGroupIngressCommand,
   DescribeSecurityGroupsCommand,
-  ImportKeyPairCommand,
+  CreateKeyPairCommand,
   DeleteKeyPairCommand,
   CreateTagsCommand,
 } from "@aws-sdk/client-ec2";
 import { STSClient, GetCallerIdentityCommand } from "@aws-sdk/client-sts";
-import { generateKeyPairSync, createPublicKey } from "crypto";
 import { createLogger } from "../lib/logger";
 import { decrypt } from "../lib/encryption";
 import type { User } from "@prisma/client";
@@ -68,38 +67,13 @@ export async function validateAwsCredentials(user: User): Promise<{ success: boo
   }
 }
 
-export function generateSshKeyPair(): { privateKey: string; publicKeyOpenssh: string } {
-  const { privateKey: privKeyPem, publicKey: pubKeyPem } = generateKeyPairSync("rsa", {
-    modulusLength: 2048,
-    publicKeyEncoding: { type: "spki", format: "pem" },
-    privateKeyEncoding: { type: "pkcs1", format: "pem" },
-  });
-
-  const pubKeyObj = createPublicKey(pubKeyPem);
-  const pubKeyDer = pubKeyObj.export({ type: "spki", format: "der" });
-
-  function sshEncodeBuffer(buf: Buffer): Buffer {
-    const lenBuf = Buffer.allocUnsafe(4);
-    lenBuf.writeUInt32BE(buf.length, 0);
-    return Buffer.concat([lenBuf, buf]);
-  }
-
-  const keyTypeStr = Buffer.from("ssh-rsa");
-  const keyTypeEncoded = sshEncodeBuffer(keyTypeStr);
-
-  const base64Encoded = pubKeyDer.toString("base64");
-  const openSshKey = `ssh-rsa ${Buffer.concat([keyTypeEncoded]).toString("base64")} pp-generated`;
-
-  return { privateKey: privKeyPem, publicKeyOpenssh: `ssh-rsa ${base64Encoded} pp-generated` };
-}
-
-export async function generateAndImportKeyPair(ec2: EC2Client, keyName: string): Promise<{ privateKey: string }> {
-  const { privateKey, publicKeyOpenssh } = generateSshKeyPair();
-  await ec2.send(new ImportKeyPairCommand({
+export async function createKeyPairAndGetPrivateKey(ec2: EC2Client, keyName: string): Promise<{ privateKey: string }> {
+  const res = await ec2.send(new CreateKeyPairCommand({
     KeyName: keyName,
-    PublicKeyMaterial: Buffer.from(publicKeyOpenssh),
+    KeyType: "rsa",
+    KeyFormat: "pem",
   }));
-  return { privateKey };
+  return { privateKey: res.KeyMaterial! };
 }
 
 export async function createPreviewSecurityGroup(ec2: EC2Client, groupName: string, port: number): Promise<string> {