code: function loadKeyPair (pub, prv, use) {
    var pubPEM, prvPEM, pubJWK
  
    try {
      pubPEM = fs.readFileSync(pub).toString('ascii')
    } catch (e) {
      throw new Error('Unable to read the public key from ' + pub)
    }
  
    try {
      prvPEM = fs.readFileSync(prv).toString('ascii')
    } catch (e) {
      throw new Error('Unable to read the private key from ' + pub)
    }
  
    try {
      pubJWK = pemjwk.pem2jwk(pubPEM)
    } catch (e) {
      throw new Error('Unable to convert the public key ' + pub + ' to a JWK')
    }
  
    return {
      pem: {
        pub: pubPEM,
        prv: prvPEM
      },
      jwk: {
        pub: {
          kty: pubJWK.kty,
          use: use,
          alg: 'RS256',
          n: pubJWK.n,
          e: pubJWK.e
        }
      }
    }
  }
docs: Load single key pair