Create a new SHA-256 hasher on each call to makeHash

MessageDigest does not seem to be thread safe, and when making multiple calls in
quick succession (like LiteFile does) will somehow result in the same API key
getting different hashes, resulting in those calls failing.

Author: BryceStevenWilley

proxyserver/src/main/java/edu/suffolk/litlab/efsp/utils/Hasher.java

@@ -7,16 +7,6 @@
 
 public class Hasher {
 
-  private static final MessageDigest digest;
-
-  static {
-    try {
-      digest = MessageDigest.getInstance("SHA-256");
-    } catch (NoSuchAlgorithmException ex) {
-      throw new AssertionError(ex);
-    }
-  }
-
   /**
    * Returns a hash of the given input string. Used to hash user IDs and API keys (neither of which
    * need salt, as they're already random).
@@ -25,6 +15,12 @@ public static String makeHash(String input) {
     if (input == null) {
       return "";
     }
-    return new String(Hex.encode(digest.digest(input.getBytes(StandardCharsets.UTF_8))));
+
+    try {
+      var shaHasher = MessageDigest.getInstance("SHA-256");
+      return new String(Hex.encode(shaHasher.digest(input.getBytes(StandardCharsets.UTF_8))));
+    } catch (NoSuchAlgorithmException ex) {
+      throw new AssertionError(ex);
+    }
   }
 }