Imagine a scenario where you write all your embarrassing secrets in a diary in a code that only you understand…
A thief photocopies every page of your diary, but since he can’t read it, he decides to keep it until he stumbles upon an idea or key to decode your messages. You carry on, confident about your code. When the thieves are able to find the key years later, your embarrassing opinions from years before are now known to the public.
This is exactly what hackers can do today: steal encrypted information today, but they don’t worry about not being able to read it yet as their strategy involves stealing and storing data and information and just waiting it out. When its possible to crack the encryption using quantum computing, the stored data will become readable and potentially catastrophic. This is exactly what HNDL (Harvest Now, Decrypt Later) is, and according to official warnings from the world’s intelligence community, it’s already happening.
What Is HNDL And How Does It Work?
HNDL is a strategy where cybercriminals intercept and steal encrypted data, storing it with the aim to decrypt it later when quantum computing can break current encryption standards. While encryption methods today, such as ECC and RSA, are secure against traditional computers, the computational power of quantum computers can easily break them.
When quantum computing with sufficient power becomes available, information previously thought to be secure could be decrypted quickly, as cybercriminals already have access to it.
An HNDL attack is a carefully planned one, and isn’t something that happens in a jiffy. It takes place in three phases or stages, often spanning years or even decades. The first phase is collecting the data, the second phase is long-term storage, and the last phase is decrypting that information in the future, hence the extended timeline.
During the first phase, “Harvest,” cybercriminals collect encrypted data and information through already existing methods such as collecting information from unprotected systems, hacking cloud storage, exploiting servers, compromising endpoints, intercepting network traffic, and the like. Despite the data being unreadable when it is stolen, it doesn’t mean that it’s safe; for the cybercriminals, it’s a future asset with potential value in the longer run. This stage is passive, and even imperceptible, and cybercriminals don’t need to decrypt the data at this point, and that’s what makes it so dangerous.
During the second phase, “Storage,” the hackers archive this encrypted data with the intention of using it in the future. This is the phase that might go on for years and even decades as the intercepted data sits in long-term intelligence stores, state-run storage, or even private criminal repositories. With low storage costs, this stage is also passive, and the risk is even greater, as there’s no active, visible, or continuing activity for cybersecurity teams to detect.
Finally, there’s the “Decrypt” phase, when quantum computing can break public-key algorithms that become vulnerable. Powerful quantum computers using algorithms like Shor’s algorithm are a threat to ECC and RSA cryptography. This is when cybercriminals become active, using quantum computing to break through the older encryption standards, decrypt stored data, and use it to wreak havoc. The result isn’t a new breach, but the delayed after-effect of the earlier theft.
Shifting Breach Dynamics
Cyberattacks today require credential theft and prompt decryption. However, HNDL doesn’t adhere to these out-of-date breach dynamics as the original theft becomes the destructive event, despite the data not being readable at the time it was intercepted or stolen. Organisations might not realize about the data theft until the intercepted information is finally decrypted and becomes a risk years later.
This delay changes risk modelling and incident response fundamentally, as the stolen data might already be in use for years until when the theft is actually discovered. HNDL exploits this timing gap before decryption via quantum computing becomes feasible, making it exceptionally risky: the cyberattack is already going on for years, despite the damage not having materialised yet.
Why HNDL Matters Now Despite Quantum Computing Not Existing Today
Even though quantum computing doesn’t exist right now, HNDL is a matter of immediate concern as cybercriminals have been actively stealing and storing encrypted data, and are doing it right now as well. It’s only a matter of time until the moment quantum technology matures that the data is supposedly “safe,” making this an immediate, real-world data security crisis. This mismatch lies at the core of the HNDL risk.
Organisations need to measure risk by how long the data needs to remain protected, and not only by whether quantum computing can break encryption today. An organisation has quantum-era exposure if the confidentiality lifespan of the data is more than the anticipated strength of the cryptography that protects it.
In the end, even AI (artificial intelligence) and quantum computing can’t be viewed in isolation, as AI being used for cyberattacks makes the need for quantum computing even more urgent. Now the conversation is already moving past viewing these technologies in isolation as despite operating on timelines, both AI and quantum computing are creating pressure on the same security foundations, including encryption, key management, and data discovery.
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