Allow multiple signing keys to be provided

src/main/java/com/amazon/dlic/auth/http/jwt/HTTPJwtAuthenticator.java

@@ -14,6 +14,8 @@
 import java.nio.file.Path;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -54,7 +56,7 @@
     private static final Pattern BASIC = Pattern.compile("^\\s*Basic\\s.*", Pattern.CASE_INSENSITIVE);
     private static final String BEARER = "bearer ";
 
-    private final JwtParser jwtParser;
+    private final List<JwtParser> jwtParsers = new ArrayList<>();
     private final String jwtHeaderName;
     private final boolean isDefaultAuthHeader;
     private final String jwtUrlParameter;
@@ -68,6 +70,7 @@
         super();
 
         String signingKey = settings.get("signing_key");
+        List<String> signingKeysSplit = new ArrayList<>();
         jwtUrlParameter = settings.get("jwt_url_parameter");
         jwtHeaderName = settings.get("jwt_header", AUTHORIZATION);
         isDefaultAuthHeader = AUTHORIZATION.equalsIgnoreCase(jwtHeaderName);
@@ -83,19 +86,31 @@
             );
         }
 
-        final JwtParserBuilder jwtParserBuilder = KeyUtils.createJwtParserBuilderFromSigningKey(signingKey, log);
-        if (jwtParserBuilder == null) {
-            jwtParser = null;
+        boolean multipleKeys = signingKey != null && signingKey.contains(",");
+        if (multipleKeys) {
+            String[] keyArray = signingKey.replace(",\\s+", ",").split(","); // Remove spaces
+            signingKeysSplit.addAll(Arrays.asList(keyArray));
         } else {
-            if (requireIssuer != null) {
-                jwtParserBuilder.requireIssuer(requireIssuer);
-            }
+            signingKeysSplit.add(signingKey);
+        }
 
-            final SecurityManager sm = System.getSecurityManager();
-            if (sm != null) {
-                sm.checkPermission(new SpecialPermission());
+        for (String key : signingKeysSplit) {
+            JwtParser jwtParser;
+            final JwtParserBuilder jwtParserBuilder = KeyUtils.createJwtParserBuilderFromSigningKey(key, log);
+            if (jwtParserBuilder == null) {
+                jwtParser = null;
+            } else {
+                if (requireIssuer != null) {
+                    jwtParserBuilder.requireIssuer(requireIssuer);
+                }
+
+                final SecurityManager sm = System.getSecurityManager();
+                if (sm != null) {
+                    sm.checkPermission(new SpecialPermission());
+                }
+                jwtParser = AccessController.doPrivileged((PrivilegedAction<JwtParser>) jwtParserBuilder::build);
             }
-            jwtParser = AccessController.doPrivileged((PrivilegedAction<JwtParser>) jwtParserBuilder::build);
+            jwtParsers.add(jwtParser);
         }
     }
 
@@ -120,7 +135,8 @@
     }
 
     private AuthCredentials extractCredentials0(final SecurityRequest request) {
-        if (jwtParser == null) {
+
+        if (jwtParsers.isEmpty() || jwtParsers.getFirst() == null) {
             log.error("Missing Signing Key. JWT authentication will not work");
             return null;
         }
@@ -157,39 +173,43 @@
             }
         }
 
-        try {
-            final Claims claims = jwtParser.parseClaimsJws(jwtToken).getBody();
+        for (JwtParser jwtParser : jwtParsers) {
+            try {
 
-            if (!requiredAudience.isEmpty()) {
-                assertValidAudienceClaim(claims);
-            }
+                final Claims claims = jwtParser.parseClaimsJws(jwtToken).getBody();
 
-            final String subject = extractSubject(claims, request);
+                if (!requiredAudience.isEmpty()) {
+                    assertValidAudienceClaim(claims);
+                }
 
-            if (subject == null) {
-                log.error("No subject found in JWT token");
-                return null;
-            }
+                final String subject = extractSubject(claims, request);
 
-            final String[] roles = extractRoles(claims, request);
+                if (subject == null) {
+                    log.error("No subject found in JWT token");
+                    return null;
+                }
 
-            final AuthCredentials ac = new AuthCredentials(subject, roles).markComplete();
+                final String[] roles = extractRoles(claims, request);
 
-            for (Entry<String, Object> claim : claims.entrySet()) {
-                ac.addAttribute("attr.jwt." + claim.getKey(), String.valueOf(claim.getValue()));
-            }
+                final AuthCredentials ac = new AuthCredentials(subject, roles).markComplete();
 
-            return ac;
+                for (Entry<String, Object> claim : claims.entrySet()) {
+                    ac.addAttribute("attr.jwt." + claim.getKey(), String.valueOf(claim.getValue()));
+                }
 
-        } catch (WeakKeyException e) {
-            log.error("Cannot authenticate user with JWT because of ", e);
-            return null;
-        } catch (Exception e) {
-            if (log.isDebugEnabled()) {
-                log.debug("Invalid or expired JWT token.", e);
+                return ac;
+
+            } catch (WeakKeyException e) {
+                log.error("Cannot authenticate user with JWT because of ", e);
+                return null;
+            } catch (Exception e) {
+                if (log.isDebugEnabled()) {
+                    log.debug("Invalid or expired JWT token.", e);
+                }
             }
-            return null;
         }
+        log.error("Failed to parse JWT token using any of the available parsers");
+        return null;
     }
 
     private void assertValidAudienceClaim(Claims claims) throws BadJWTException {

src/main/java/org/opensearch/security/util/KeyUtils.java

@@ -54,8 +54,8 @@ public JwtParserBuilder run() {
                         PublicKey key = null;
 
                         final String minimalKeyFormat = signingKey.replace("-----BEGIN PUBLIC KEY-----\n", "")
-                            .replace("-----END PUBLIC KEY-----", "");
-
+                            .replace("-----END PUBLIC KEY-----", "")
+                            .trim();
                         final byte[] decoded = Base64.getDecoder().decode(minimalKeyFormat);
 
                         try {