RSA / ECDSA keys

JSON Web Keys (JWK) is a format specified in RFC7517 for storing RSA/EC/AES keys in a JSON based format. It can be used to import/export such keys in the browser using the new W3C WebCryptoAPI.

The jose package makes it easy to read/write such keys in R for use with JWT or any other functionality from the openssl package.

library(openssl)
Linking to: OpenSSL 1.1.1g  21 Apr 2020
library(jose)

# Generate a ECDSA key
key <- openssl::ec_keygen()
jsonlite::prettify(write_jwk(key))
{
    "kty": "EC",
    "crv": "P-256",
    "x": "MQxr7y-62pqJYddQdE5HADckumvjMeKrG99PpDgxdOc",
    "y": "dJk8JAZjOK5eme_s_LBUMtv2zeaTZ-2sXTeajP7Fl8s",
    "d": "R6xpVCZZdj9ELfm-64Cu87Qpcpa9fPoYs9jlfcGbS0w"
}
 
# Use public key
pubkey <- as.list(key)$pubkey
json <- write_jwk(pubkey)
jsonlite::prettify(json)
{
    "kty": "EC",
    "crv": "P-256",
    "x": "MQxr7y-62pqJYddQdE5HADckumvjMeKrG99PpDgxdOc",
    "y": "dJk8JAZjOK5eme_s_LBUMtv2zeaTZ-2sXTeajP7Fl8s"
}
 
# Read JWK key
(out <- read_jwk(json))
[256-bit ecdsa public key]
md5: a11561813ea684cf277ede109bb5f93a
identical(pubkey, out)
[1] TRUE

AES/HMAC keys

JWT also specifies a format for encoding AES/HMAC secrets. Such secret keys are simply raw bytes.

# Random secret
(key <- rand_bytes(16))
 [1] d5 8d bc 71 61 23 53 02 3f 72 91 45 85 90 bc 70
(jwk <- write_jwk(key))
{"kty":"oct","k":"1Y28cWEjUwI_cpFFhZC8cA"} 
read_jwk(jwk)
 [1] d5 8d bc 71 61 23 53 02 3f 72 91 45 85 90 bc 70