Update README.md

README.md

@@ -126,22 +126,26 @@ curl -F "password=hunter2" -F "[email protected]" http://localhost:3000/api/uploa
 
 ```json
 {
-  "id": "YOWJyhDXxhe3-L8MpEFBbA",
-  "key": "YOWJyhDXxhe3-L8MpEFBbAN_e93AqTrEMYutkmStScq5VfbQlrqUt9yHkqmeRp7OQ",
-  "url": "/d/YOWJyhDXxhe3-L8MpEFBbAN_e93AqTrEMYutkmStScq5VfbQlrqUt9yHkqmeRp7OQ",
+  "id": "xmK5lLMRErlN",
+  "key": "xmK5lLMRErlN",
+  "url": "/d/xmK5lLMRErlN",
   "originalName": "example.zip",
   "size": 123456,
   "protected": true
 }
 ```
 
+`id` and `key` are the same 12-character base64url token (~72 bits of entropy);
+the short length keeps share URLs tidy, and the required password adds a second
+factor of protection.
+
 ### `GET /d/:key` (also `HEAD`)
 
 Every file is password-protected. Without a valid auth cookie the server shows a
 password prompt; a wrong or non-existent key returns a generic `404`.
 
 ```bash
-curl -O http://localhost:3000/d/YOWJyh...7OQ   # prompts for password first
+curl -O http://localhost:3000/d/xmK5lLMRErlN   # prompts for password first
 ```
 
 ### Password protection
@@ -185,10 +189,11 @@ paths or stack traces.
 
 ## Security model
 
-- **Secrets.** Each file gets a fresh 128-bit id + 256-bit secret via
-  `crypto.randomBytes`. Keys are encoded base64url; brute forcing them is
-  computationally infeasible. No timestamps, incrementing ids, `Math.random()`,
-  or filenames are ever used as secrets.
+- **Secrets.** Each file gets a fresh 72-bit (9 random bytes) base64url key via
+  `crypto.randomBytes`, used as both the share id and the download key. Keys are
+  encoded base64url; guessing one is infeasible at scale, and the required
+  password is an added second factor. No timestamps, incrementing ids,
+  `Math.random()`, or filenames are ever used as secrets.
 - **At-rest.** Only a SHA-256 hash of the key is persisted. Comparisons use
   constant-time `timingSafeEqual`.
 - **Passwords.** Every file has a password stored only as an **scrypt** hash