Switch hashing function of engineApiKeyHash to sha512 from sha256 (#2736

)

* use sha512 hashing function instead of sha256

* update changelog

* Update CHANGELOG.md

CHANGELOG.md

@@ -6,7 +6,7 @@
 - `apollo-server-core`: Allow request pipeline life-cycle hooks (i.e. plugins) to modify the response's `http.status` code (an integer) in the event of an error.  When combined with the new `didEncounterErrors` life-cycle hook (see above), this will allow modifying the HTTP status code in the event of an error.  [PR #2714](https://github.com/apollographql/apollo-server/pull/2714)
 - `apollo-server-lambda`: Set `callbackWaitsForEmptyEventLoop` to `false` for `OPTIONS` requests to return as soon as the `callback` is triggered instead of waiting for the event loop to empty. [PR #2638](https://github.com/apollographql/apollo-server/pull/2638)
 - `apollo-server`: Support `onHealthCheck` in the `ApolloServer` constructor in the same way as `cors` is supported.  This contrasts with the `-express`, `-hapi`, etc. variations which accept this parameter via their `applyMiddleware` methods and will remain as-is.  [PR #2672](https://github.com/apollographql/apollo-server/pull/2672)
-- core: Expose SHA-256 hex hash digest of the Engine API key to plugins, when available, as `engine.apiKeyHash`. [PR# 2685](https://github.com/apollographql/apollo-server/pull/2685)
+- core: Expose SHA-512 hex hash digest of the Engine API key to plugins, when available, as `engine.apiKeyHash`. [PR #2685](https://github.com/apollographql/apollo-server/pull/2685) [PR #2736](https://github.com/apollographql/apollo-server/pull/2736)
 - `apollo-datasource-rest`: If another `Content-type` is already set on the response, don't overwrite it with `application/json`, allowing the user's initial `Content-type` to prevail. [PR #2520](https://github.com/apollographql/apollo-server/issues/2035)
 - `apollo-cache-control`: Do not respond with `Cache-control` headers if the HTTP response contains `errors`. [PR #2715](https://github.com/apollographql/apollo-server/pull/2715)
 - `apollo-server-core`: Skip loading `util.promifisy` polyfill in Node.js engines >= 8.0 [PR #2278](https://github.com/apollographql/apollo-server/pull/2278)

packages/apollo-server-core/src/ApolloServer.ts

@@ -341,7 +341,7 @@ export class ApolloServerBase {
 
     const apiKey = getEngineApiKey(engine);
     if (apiKey) {
-      this.engineApiKeyHash = createSHA('sha256')
+      this.engineApiKeyHash = createSHA('sha512')
         .update(apiKey)
         .digest('hex');
     }