square/js-jose

How to use it with backend-generated key?

Deliaz opened this issue · 6 comments

Deliaz commented

Is that possible to import and use public part of RSA key which made on a backend.
I mean keys from ssh-keygen or openssl.

I tried to import key with base64 in n-component but got an error (something about "leading zero in JWK")

csstaub commented

You can form an RSA public key from n/e like this:

var rsa_key = Jose.Utils.importRsaPublicKey({
    "n": "c2:4b:af:0f:2d:2b:ad:36:72:a7:91:0f:ee:30:a0:95:d5:3a:46:82:86:96:7e:42:c6:fe:8f:20:97:af:49:f6:48:a3:91:53:ac:2e:e6:ec:9a:9a:e0:0a:fb:1c:db:44:40:5b:8c:fc:d5:1c:cb:b6:9b:60:c0:a8:ac:06:f1:6b:29:5e:2f:7b:09:d9:93:32:da:3f:db:53:9c:2e:ea:3b:41:7f:6b:c9:7b:88:9f:2e:c5:dd:42:1e:7f:8f:04:f6:60:3c:fe:43:6d:32:10:ce:8d:99:cb:76:f7:10:97:05:af:28:1e:39:0f:78:35:50:7b:8e:28:22:a4:7d:11:51:22:d1:0e:ab:6b:6f:96:cb:cf:7d:eb:c6:aa:a2:6a:2e:97:2a:93:af:a5:89:e6:c8:bc:9f:fd:85:2b:0f:b4:c0:e4:ca:b5:a7:9a:01:05:81:93:6b:f5:8d:1c:f7:f3:77:0e:6e:53:34:92:0f:48:21:34:33:44:14:5e:4a:00:41:3a:7d:cb:38:82:c1:65:e0:79:ea:a1:05:84:b2:6e:40:19:77:1a:0e:38:4b:28:1f:34:b5:cb:ac:c5:2f:58:51:d7:ec:a8:08:0e:7c:c0:20:c1:5e:a1:4d:b1:30:17:63:0e:e7:58:8e:7f:6e:9f:a4:77:8b:1e:a2:d2:2e:1b:e9",
    "e": 65537
}, "RSA-OAEP");

Note that the n value here is not base64-encoded.

Deliaz commented

Yeah, I got it, but could you please suggest me a way to get/convert such format of key?

csstaub commented

It's just a hex-encoded version (with interspersed :) of the integer. I would convert it on the backend before sending it to the client.

csstaub commented

Alternatively, you can also import keys in JWK format. See here for some examples: https://github.com/square/js-jose/blob/b9b66ef449fe4414ccac6bbdd2870a2dff3baf2c/test/jose-jws-test.html

Deliaz commented

I tried node-rsa to convert public PEM to component view, but it seems that output format still different.
Do you use your own script?

csstaub commented

I don't know what node-rsa does so I can't help you with that. If you don't know how to convert the key yourself there's plenty of already existing packages to be found on GitHub that can convert PEM blocks to JWK which you could use.