Glossary

62 terms

• API (Application Programming Interface)

  A way for apps to talk to online services. When sniffQR checks a URL, it sends a request to an API and gets back a safety verdict.

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• API Key

  A unique code that identifies your app to an online service. Think of it like a password that lets sniffQR talk to threat scanning services on your behalf.

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• Authentication

  The process of proving your identity (Face ID or Touch ID on iPhone, face unlock or a fingerprint on Android, or your device passcode, PIN, pattern or password) to unlock the app.

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• Authorization Header

  A piece of information sent with a network request to prove you have permission to access a service. Used by custom threat feeds to verify your identity.

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• Bidirectional Control Characters

  Invisible characters that change the direction text is displayed (left-to-right or right-to-left). Attackers can use them to make a URL appear to point somewhere different than it actually does. sniffQR strips them, counts them, and re-marks their positions in what it shows you, so you can see exactly where they were hiding.

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• Billing Account

  A payment method linked to a cloud service like Google Cloud. Required to use Google Web Risk. Google sets Web Risk pricing and can change it: cloud.google.com/web-risk/pricing

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• Biometrics

  Using your body's unique features, a fingerprint or your face, to verify your identity. On iPhone that is Touch ID or Face ID; on Android it is fingerprint unlock or face unlock.

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• Brand Impersonation

  A domain built to be mistaken for a well-known company's. sniffQR checks 60 high-value brands four ways: digit and letter substitution (examp1e.net), lookalike-character substitution (exаmple.com), typo-squats one edit away (exampel.org, examplle.org), and subdomain impersonation (example.com.evil.example). The check also runs on the recipient domains in an email payload and on every address in a scanned contact card: on your device only, never sent anywhere.

• Certificate Pinning

  A security measure that ensures your app only communicates with the real server, not an impersonator. sniffQR uses this for built-in services like Google Web Risk and VirusTotal in the apps; a browser extension cannot pin certificates and relies on the TLS checks the browser itself performs.

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• Clipboard

  A temporary storage area on your device for copied text or images. When you 'copy' something, it goes to the clipboard. sniffQR can scan QR codes from images you've copied.

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• Clipboard Hijacking

  A type of attack where malware watches what you copy and secretly replaces it. For example, swapping a cryptocurrency address with the attacker's address.

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• Cross-Site WebSocket Hijacking (CSWSH)

  An attack where a malicious WebSocket connection hijacks your active session on another site, letting an attacker act as you. It can also target services running on your device (localhost) that aren't exposed to the internet. QR codes containing ws:// or wss:// URLs may be used for this type of attack.

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• Cryptocurrency

  Digital money that uses encryption to secure transactions, like Bitcoin or Ethereum. It operates without a central bank and uses blockchain technology to record transfers.

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• Cryptocurrency Address

  A string of letters and numbers that identifies a crypto wallet, similar to a bank account number. QR codes often contain these for payments.

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• Custom Threat Feed

  Your own server that scans QR code content for threats. You provide the URL and sniffQR sends scan requests to it, letting you use your own threat intelligence. Contact cards, Wi-Fi, calendar, crypto and 2FA codes are never sent to a custom feed: a Wi-Fi password, a 2FA secret, a wallet address and a contact's details always stay on your device.

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• Domain

  The human-readable name of a website, like 'google.com' or 'sniffqr.com'. It's the main part of a URL that identifies who owns the site.

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• Encryption

  Scrambling data so only authorized parties can read it. sniffQR encrypts your scan history on your device so it can't be read by other apps.

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• Engine

  In the context of VirusTotal, an 'engine' is one of many independent security scanners that analyze a URL. When results say '3 engines flagged this,' it means 3 separate scanners found issues.

• Free Tier

  A level of service offered at no cost, usually with usage limits. Google Web Risk has one, and its terms are Google's to set. sniffQR does not know your remaining allowance and never claims to. The 3,000-lookups-a-day figure you see in sniffQR is its own client-side guard, a self-imposed cap that stops the app spending your Google Cloud quota on your behalf. It is not Google's limit. Google sets Web Risk pricing and can change it: cloud.google.com/web-risk/pricing

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• Google Cloud Console

  Google's web-based dashboard for managing cloud services. You use it to create a project, enable the Web Risk API, and generate your API key.

• Google Web Risk

  A Google service that maintains a database of known dangerous websites. sniffQR checks URLs against it for malware, social engineering and unwanted software, using your own API key. sniffQR Pro also offers Google Web Risk (Offline), which matches against a copy of the database on your device.

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• Grace Period

  In sniffQR this means one thing only: the short window after you leave the app before 'Lock on Exit' engages again, so you do not have to re-authenticate every time you briefly switch apps. You choose the length with 'Lock after'. It is not a billing term: sniffQR Pro is a one-time purchase, so there is no subscription to lapse and nothing to renew.

• Hidden Characters

  Characters that take up no visible space but change how text is read: zero-width spaces, word joiners, bidirectional overrides, control characters, byte-order marks and tag characters. They can make a malicious URL look ordinary. sniffQR strips them, counts them, and marks where they were so you can see the trick.

• Homoglyph

  A character that looks nearly identical to another but is actually different. For example, a Cyrillic 'а' looks like a Latin 'a'. Attackers use these to create fake website addresses that look legitimate. sniffQR checks a curated set of them across five scripts (Cyrillic, Greek, Armenian, Georgian and Cherokee), folds full-width and fancy-font Latin back to plain letters, and names each finding by script and by its official Unicode character. It never invents a name it does not have. The check runs on every payload type, not just URLs.

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• HTTP

  The basic protocol for loading websites. HTTP is not encrypted, meaning anyone on the network can see what you're doing. See HTTPS for the secure version.

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• HTTPS

  The secure version of HTTP. The 'S' stands for Secure. HTTPS encrypts the connection between your device and the website so others can't eavesdrop. Look for the lock icon in your browser.

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• Jailbroken Device

  An iPhone or iPad that has been modified to remove Apple's built-in security restrictions. This can expose the device to malware and make security checks unreliable. sniffQR warns you if it detects one, but does not stop you using the app. The Android equivalent is a rooted device.

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• JSON

  A standard text format for exchanging data between apps and servers. When sniffQR talks to a custom threat feed, it sends and receives data in JSON format.

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• Keychain / Android Keystore

  Your device's built-in secure storage for secrets, protected by hardware encryption. sniffQR keeps your API keys there: the Keychain on iPhone and iPad, and encrypted preferences keyed by the Android Keystore on Android.

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• Leet Substitution

  Swapping letters for digits that look like them, like 0 for o or 1 for l, to build a domain that reads like a real brand at a glance. sniffQR checks for it, but only against known brand names, so an ordinary name like abc123.com is never flagged.

• Lock on Exit

  A sniffQR setting that asks for your device's unlock when you come back to sniffQR after leaving it: Face ID, Touch ID or your passcode on iPhone; fingerprint, face unlock or your screen lock on Android. Moving between screens inside sniffQR, or opening a photo, a preview or the share sheet from sniffQR, never locks. 'Lock after' sets how long you can be away before it asks. Your device needs a passcode or screen lock for this to work.

• Malware

  Short for 'malicious software.' Any program designed to harm your device, steal your data, or take control without your permission.

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• Offline Mode

  When your device has no internet connection. sniffQR still works: scanning, decoding and the whole on-device detection engine need no connection at all. sniffQR Pro adds Google Web Risk (Offline), which matches links against a threat database stored on your device. If a possible match is checked with Google, only a short piece of the link's fingerprint is sent, never the link itself. You start the first download; after that the list updates itself while the app is open and online. There is no background sync.

• Passcode / Screen Lock

  The code you set on your device to lock it: a passcode on iPhone, or a PIN, pattern or password on Android. sniffQR can use it as a fallback when biometrics aren't available, and 'Lock on Exit' fails closed: if it cannot verify you, it does not open.

• Phishing

  A trick where attackers create fake websites or messages that look real to steal your passwords, credit card numbers, or other personal information.

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• Potentially Harmful File Types

  File types that pose a security risk when downloaded from unknown sources. sniffQR recognizes a curated set in four families: executables and scripts (.exe, .bat, .sh), archives and disk images (.zip, .iso, .dmg), macro-enabled documents (.docm, .xlsm), and app installers (.apk, .ipa). It also catches double extensions in both directions, so invoice.pdf.exe and setup.zip.txt are both flagged.

• Premium API Key

  A paid tier of API access that unlocks more features or higher usage limits. VirusTotal requires a premium key for third-party app use per their Terms of Service.

• Private codes

  The five QR types sniffQR keeps off the network by default: contact cards, Wi-Fi, calendar, crypto/wallet and 2FA/OTP. Their contents never leave your device and are never sent to a custom feed. A Settings switch, off by default, lets you opt in to checking web links found inside them, and says plainly that doing so reveals the link.

• Punycode

  A way to represent international domain names using only basic ASCII characters. A domain built from lookalike characters has a Punycode form (like 'xn--exmple-4nf.com') that reveals it. sniffQR shows you both side by side: what you see, and what it actually is.

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• QR Code

  Short for 'Quick Response' code. A square barcode that stores information like website links, text, WiFi passwords, or contact details. Your phone's camera can read them instantly.

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• Quota

  The maximum number of requests you're allowed to make to a service within a time period. Exceeding your quota may result in temporary blocks or charges. sniffQR counts its own lookups on your device and stops at 3,000 a day so it cannot run your quota up without you noticing. That ceiling is sniffQR's, not the provider's, and it is deliberately conservative.

• Rate Limit

  A cap on how many requests you can make to a service in a given time period. If you hit the rate limit, you'll need to wait before scanning again.

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• Redirect

  When a URL automatically sends you to a different URL. Shortened links (like bit.ly) use redirects. Attackers sometimes chain multiple redirects to hide a malicious destination.

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• Redirect Chain

  A series of redirects where one URL leads to another, which leads to another, and so on. When you ask it to, sniffQR follows these chains to find the final destination and check each step for threats.

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• Rooted Device

  An Android device that has been modified to grant apps administrator-level access, removing the protections that normally keep apps separated from each other. This can expose the device to malware and make security checks unreliable. sniffQR warns you if it detects one, but does not stop you using the app. The iPhone equivalent is a jailbroken device.

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• Shell Command

  A text instruction that tells your computer's operating system to do something. QR codes containing shell commands could be dangerous if executed.

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• Smart Rescan

  A Pro feature that replays a past scan against fresher data. It re-runs exactly the selection you approved the first time (the same URLs, nothing more), so the same question gets a current answer. If your service settings have changed since the original scan, the rescan says so.

• Social Engineering

  Manipulating people into giving up confidential information or taking unsafe actions. Phishing is the most common form.

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• Threat Intelligence

  Information about known online threats (malicious websites, phishing pages, malware sources) collected and maintained by security companies like Google and VirusTotal.

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• TLS (Transport Layer Security)

  The encryption technology behind HTTPS. TLS creates a secure, encrypted connection between your device and a website so your data can't be intercepted.

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• TLS Downgrade

  When a secure HTTPS connection is redirected to an insecure HTTP one. This can expose your data to eavesdroppers. sniffQR can block these automatically (Settings > Block insecure redirects) and always warns you when one is detected.

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• Two-Factor Authentication (2FA)

  An extra layer of security that requires a second form of verification (like a code from an app) in addition to your password. QR codes are commonly used to set up 2FA apps like Google Authenticator.

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• Typosquatting

  Registering a domain one small mistake away from a real one (exampel.org, examplle.org) and waiting for the mistake. sniffQR flags a host that is within a single edit (an inserted, deleted, changed or swapped character) of a well-known brand.

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• Unicode

  A universal standard for representing text characters from every writing system in the world. Attackers can exploit Unicode to disguise malicious content using lookalike characters.

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• Unknown

  One of sniffQR's four verdicts, and the most important one to understand. 'Unknown' means no enabled service produced a result, or when sniffQR could not confirm where a link goes (a short link not yet checked, or a dead link): the code is not safe, not dangerous, just unverified. It is what you get when no service is configured, when every service was skipped or errored, when a destination never answered, or when a service simply has no record of the link. sniffQR reports 'Unknown' rather than assuming the best: no check means 'Unknown', never 'Safe'. An 'Unknown' result still asks you to confirm before anything opens.

• Unwanted Software

  Programs that aren't technically malware but do things you didn't agree to, like changing your homepage, showing excessive ads, or bundling other software without asking.

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• URL

  Short for 'Uniform Resource Locator.' A web address like 'https://example.com' that tells your browser where to find a page or resource on the internet.

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• Verdict

  sniffQR's assessment of a scanned QR code. There are four: 'Safe', 'Potentially Suspicious', 'Likely Malicious', and 'Unknown'. Individual hops in a redirect chain can also read 'Not checked'. The verdict is based on the results from the threat intelligence services you have configured, plus on-device analysis.

• Verdicts

  sniffQR's verdicts work like a traffic light so they are easy to read at a glance: 'Safe' is green, 'Potentially Suspicious' is yellow, 'Likely Malicious' is red, and 'Unknown' is gray, meaning there wasn't enough to go on. They describe what the checks you use found, not a guarantee. 'Safe' means no known threat was found. Sites can be hacked, new scams appear every day, and threat services can be wrong or slow to catch them, so trust your judgment too.

• VirusTotal

  A security service that checks URLs and files against dozens of independent security scanners simultaneously. Requires a premium API key for use in third-party apps. sniffQR checks it with a SHA-256 fingerprint of the URL, so the URL itself is never sent and nothing is ever submitted for analysis.

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• WebSocket

  A communication protocol that opens a persistent, two-way connection between your device and a server. Unlike regular web requests, WebSockets stay open and can send data in both directions continuously. QR codes with ws:// or wss:// URLs open WebSocket connections.

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• WiFi Credentials

  The network name (SSID) and password for a WiFi network. QR codes can store these so you can join a network by scanning instead of typing the password.

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