+maxRetryAttempts, padding & safer error handling. Improved readability & comments.

frontend/src/components/utilities/checks/checkIsPasswordBreached.ts

@@ -1,47 +1,83 @@
 import axios from "axios";
 import { createHash } from "crypto"; // added types from @types/node
 
-export const checkIsPasswordBreached = async (password: string) => {
   // see API details here: https://haveibeenpwned.com/API/v3#SearchingPwnedPasswordsByRange
   // in short, the pending password is hashed (SHA-1), the first 5 chars are sliced and compared against a ranged hash table
-  // if there is a match, that password has been involved in a password breach and should NOT be accepted
-
+  // this hash table is formed from the 5 char hash prefix (ie. 00000-FFFFF) so 16^5 results
+  // returns a hash table of 800-1000 results
+  // padding has been added to prevent MiTM attacker determining which hash table was called by the response size
+  // the last 35 chars of the password hash are compared client-side against the table
+  // if there is a match, that password has been involved in a password breach (ie. pwnd) and should NOT be accepted
   // the database consists of ~700 mln breached passwords and is continuously updated, including with law enforcement ingestion
   // https://www.troyhunt.com/open-source-pwned-passwords-with-fbi-feed-and-225m-new-nca-passwords-is-now-live/
 
+  // The HIBP API follows NIST guidance (pg.14) https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-63b.pdf
+  // "When processing requests to establish and change memorized secrets, verifiers SHALL compare
+  // the prospective secrets against a list that contains values known to be commonly-used, expected,
+  // or compromised. For example, the list MAY include, but is not limited to:
+  // • Passwords obtained from previous breach corpuses.
+  // • Dictionary words.
+  // • Repetitive or sequential characters (e.g. ‘aaaaaa’, ‘1234abcd’).
+  // • Context-specific words, such as the name of the service, the username, and derivatives
+  //   thereof."
+
+export const checkIsPasswordBreached = async (password: string) => {
   const dataBreachCheckAPIBaseURL = "https://api.pwnedpasswords.com/range/"; // added to CSP
+  const maxRetryAttempts = 3;
 
   try {
     const textEncoder = new TextEncoder();
     const encodedPwd = textEncoder.encode(password);
     const hash = createHash("sha1").update(encodedPwd).digest();
+    const hashedPwd = hash.toString("hex").toUpperCase();
+    const hashedPwdToSend = hashedPwd.slice(0, 5); // ONLY the first five hash chars are sent
+    const rangedHashTableUri = `${dataBreachCheckAPIBaseURL}${hashedPwdToSend}`;
+    
+    let response;
+    let retryAttempt = 0;
 
-    const hashedPwd = Array.from(new Uint8Array(hash))
-      .map((byte) => byte.toString(16).padStart(2, "0"))
-      .join("")
-      .toUpperCase();
+    while (retryAttempt < maxRetryAttempts) {
+      try {
+        response = await axios.get(rangedHashTableUri, {
+          headers: {
+            "Add-Padding": "true", // see https://www.troyhunt.com/enhancing-pwned-passwords-privacy-with-padding/
+            "Content-Type": "text/plain",
+          },
+        });
 
-    // ONLY the first five SHA-1 hash chars need to be sent (must be over HTTPS)
-    const hashedPwdToSend = hashedPwd.slice(0, 5);
-
-    const response = await axios.get(`${dataBreachCheckAPIBaseURL}${hashedPwdToSend}`);
-    const responseData = response.data.toUpperCase();
-
-    // compare against the API's ranged db's hash table
-    const isBreachedPassword = responseData.includes(hashedPwd.slice(5, 40));
-
-    // Clear the hashed password from memory as a precaution
-    const zeroBuffer = new Uint8Array(encodedPwd.length);
-    encodedPwd.set(zeroBuffer);
-
-    return isBreachedPassword; // boolean: true indicates the password has been involved in a data breach
-  } catch (err: any) {
-    if (axios.isAxiosError(err) && err.response && err.response.status === 429) {
-      console.error("Received a 429 response from the Pwnd Passwords API");
-      // Handle the 429 error here (not 100% sure what the rate limits are for the password API but looks like <10 calls/min)
-      // an error here should probably not cause the setting/resetting/changing password to fail (unless desired)
-    } else {
-      console.error(err);
+        if (response.status === 200) {
+          break;
+        } else {
+          retryAttempt++;
+        }
+      } catch (err) {
+        if (!axios.isAxiosError(err)) {
+          throw err;
+        }
+        retryAttempt++;
+      }
     }
+
+    if (response && response.status === 200) {
+      const responseData = response.data.toUpperCase();
+      // compare last 35 hash chars to the returned ranged hash table
+      // returns a boolean: true indicates the password has been involved in a data breach (ie. pwnd)
+      const isBreachedPassword = responseData.includes(hashedPwd.slice(5, 40));
+
+      // Clear the hashed password from memory as a precaution
+      const zeroBuffer = new Uint8Array(encodedPwd.length);
+      encodedPwd.set(zeroBuffer);
+
+      return isBreachedPassword;
+    }
+
+    console.error(
+      `Received a non-200 response (${response ? response.status : "unknown"}) from the Pwnd Passwords API`
+    );
+    return false; // better to return a safe response if no breach can be determined
+  } catch (err: any) {
+    console.error("An unexpected error has occurred:", err.message);
+    return false; // Return a safe response in case of unexpected errors 
+    // the HIBP API could return 400 (empty string supplied), 429 or 503 if Cloudflare edge node is down)
   }
 };