Import key with crypto in middleware.ts

[Chanizo]

Summary

Hello,
I am struggling to use WebCrypto in my Nextjs middleware, to replace jsonwebtoken used in server side (not available in Edge Runtime)
I have public/private keys and I am trying to import my private key to sign data
These examples are not working in my middleware, did someone succeeded ?
https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/importKey#pkcs_8_import

I am always obtaining this error : ⨯ Error [DataError]: Invalid keyData

Just replaced str2ab function by 'new TextEncoder().encode(privateKey)' because I had a format issue using it. I tried with my key, and keys from given examples, but none is working...

Nextjs : v14 with Typescript

My code :

  const pemFooter = '-----END RSA PRIVATE KEY-----';
  const pemContents = PEM.substring(
    pemHeader.length,
    PEM.length - pemFooter.length - 1
  );
  const atobPrivateKey = atob(pemContents);
  const privateKeyAsCryptoKey = await crypto.subtle.importKey(
    'pkcs8',
    new TextEncoder().encode(atobPrivateKey),
    {
      name: 'RSA-PSS',
      hash: 'SHA-256',
    },
    true,
    ['sign']
  );```

[icyJoseph]

Honestly, I am not the biggest fan of going around installing packages, but jose has been such a solid library when it comes to doing crypto on edge environments... give it a go: https://www.npmjs.com/package/jose

[Chanizo]

Thank you for your answer @icyJoseph !
I tried jose and I have encountered same problem... but I found the the solution
In fact I was using basic ssh-keygen / openssl commands to generate a public / private key pair, but it was in format PKCS#1 by default. Jose and crypto libraries need more recent format, like PKCS#8 (private key) and SPKI (public key)

Related issue : panva/jose#345

Old commands :

openssl rsa -in my.key -pubout -outform PEM -out my.key.pub```

New commands :
```ssh-keygen -t rsa -b 4096 -m PKCS8 -f my.key -N ''
openssl pkey -in my.key -pubout -outform PEM -out my.key.pub```

[leerob]

Good news everyone, Node.js Middleware support landed in Next.js 15.2 (experimental). This is now ready for testing. For any issues you run into, please open new issues so we can track and address before marking it as stable. Thank you!

https://nextjs.org/blog/next-15-2#nodejs-middleware-experimental