Post Quantum Cryptography Reading Time: 7 minutes

New Risks to Post-Quantum Kyber KEM: What are Timing Attacks and how do they threaten Encryption? 

Quantum-resistant cryptography, Kyber Key Encapsulation Mechanism (KEM), is a promising candidate that can provide strong Quantum protection against quantum attacks Using a lattice-based approach, Kyber KEM offers strong security in terms of quantum adversaries while maintaining improved performance in practical applications.

It offers promise, but amid optimism about Kyber KEM’s resilience to quantum threats, another concern has emerged: time attack. Post-quantum cryptography aims to seamlessly integrate with current networks and networks to create cryptographic systems that are secure against quantum-classical computers. 

Timing attacks, a class of side-channel attacks, test how long the computer takes to process information. Even something as simple as that could reveal clues to the secret key used by Kyber KEM, a new system designed to keep our data safe from powerful quantum computers, ensuring the future security of Kyber KEM (or similar quantum cryptography) involves continuously reducing the time required for potential attacks to comprehend it.

Timing attack

Side-channel attacks in cryptography take benefit of random activities at some point of cryptographic operation. These leaks can do things like: 

  • Time: Time required for this system to run.
  • Power intake: The amount of energy ate up via a device for the duration of the calculation. 
  • Electromagnetic emission: Small electric indicators emitted by using a device. 

Timing attacks in most cases consciousness on timing in cryptographic packages. Every pc software takes a while, and in cryptography these operations can occasionally be stricken by the statistics being generated. This manner that the processing time can be slightly quicker or slower depending at the particular parameters concerned. 

In a timing attack, the attacker makes use of information from the application’s cryptographic characteristic. This exposure is not to the real statistics however to the software runtime. 

The attacker works by presenting diverse records to the software, tracking usage time, and statistically reading these facts to obtain relevant statistics. 

An example of a time attack might be an attacker the usage of a susceptible internet utility to extract touchy records, including usernames or credit score card numbers. 

  • The attacker sends multiple requests to the internet software, every with slightly special parameters or payloads. 
  • The attacker watches the server response time and reveals that some requests take longer to method than others. 
  • A long response time shows that the server is acting extra paintings or verifying that precise request. 
  • The attacker will continue to ship the same request while making plans to trade the parameters unless an instance that fits the appropriate reaction time and statistics is chosen. 

Using this information, an attacker could exploit the vulnerability to remove sensitive data processed by the server. 

Why are timing attacks a concern? 

Time attacks are dangerous because they can be very subtle. The difference in execution time can be incredibly small, so the attacker must repeat the operation several times and mathematically analyze the encrypted data but only if the cryptographic implementation is not designed to resist time attack, the attacker can steal the private key and other sensitive information that was available at the time. 

How Timing Attack Works 

Timing attacks use random information during cryptographic operation. They focus on the time it takes for a program to perform a specific task. Here’s the basic idea: 

  • Poor implementation: Some cryptographic algorithms are implemented in such a way that execution time can have an impact on the data being processed. This can be caused by things like branch statements or cache hits. 
  • Attacker’s strategy: the attacker sends various inputs (such as various password guesses) to the system and carefully measures how long it takes the system to respond to each attempt 
  • Statistical analysis: By repeating this process several times and statistically analyzing the collected data, the attacker should be able to identify patterns in temporal variation These systems can reveal clues about private keys or other important information. 

Why is this relevant to Kyber KEM? 

Kyber KEM is a promising quantum background cryptography framework. While it provides strong protection against powerful quantum computers, it is still vulnerable to certain attack methods, such as time attacks

The private key can affect the mathematical operations used in Kyber KEM. This means that a sophisticated attacker can exploit the time variation of the decryption process to recover the private key. When the key used in the Kyber KEM is attacked. Instead of listening for recordings as the connection progresses, the attacker listens for subtle changes in processing speed based on the secret key. 

Kyber KEM: Kyber is a Key Encapsulation Method (KEM) 

Kyber KEM, a promising post-quantum cryptography system designed to resist attacks from powerful quantum computers, encountered a vulnerability known as KyberSlash These flaws affect many Kyber KEM applications, including those that industry including using popular ones like Mullvad VPN and Signal Messenger. The issue arises in how Kyber handles department functions during decryption. These transactions can take a little longer depending on the type of private key being used. 

By carefully measuring this time shift, attackers can use KyberSlash to recover private keys, rendering the encryption useless. This highlights the importance of continuous research and development in cryptography, even for supposedly secure systems like Kyber KEM. 

The Kyber Key Encapsulation Mechanism (KEM) is a cryptographic technique designed to securely exchange private keys between parties in a network. It is specially designed to resist attacks from classical quantum computers.  

The Vulnerability: 

  • While robust towards direct assaults, Kyber KEM, like many cryptographic structures, is predicated on unique mathematical operations in its decryption manner 
  • The hassle arises while the time it takes to carry out these operations may be suffering from the precise values of the account, particularly the ones for personal keys. 
  • This way that processing time may be barely faster or slower relying on which Kyber KEM functions the non-public key uses.  

How Attackers Exploit Kyber KEM: 

  • A skilled attacker can take advantage of this vulnerability by using connecting diverse gadgets to the system and punctiliously measuring the reaction times. 
  • By statistically reading this statistics, the attacker may also be capable of put together the private key utilized by Kyber KEM. 
  • Imagine that you are trying to disassemble a verbal exchange tool. The onslaught of time averted direct disclosure of individual numbers. However, it could inform an attacker how quick the decryption gadget responds to their tries depending on whether they’re approaching the suitable connection.

Why should we mitigate timing attacks?

We want to lower timing assaults for plenty motives, especially as regards to securing effective cryptographic structures like Kyber KEM: 

  • Compromised Safety

    Timing assaults, even though subtle, can screen sensitive data which includes non-public keys. If an attacker manages to take advantage of the temporal flexibility of Kyber KEM’s decryption technique, they will basically advantage access to the complete encryption method, rendering it vain. This can cause extreme problems in defensive sensitive transmission information.

  • Silent Threats

    Unlike brute force assaults, which could improve alarms, time attacks are covert. Unintentional leaks are used sooner or later of everyday operation, making detection hard. This messes up the device with out everyone noticing.

  • Widespread Impact

    Time assaults aren’t constrained to Kyber KEM. Cryptographic systems that rely upon specific mathematical operations are compromised. Reducing time attacks allows enhance the overall protection environment for cryptography.

  • Future-proofing Safety

    Quantum pc structures appreciably compromise current-day-day encryption strategies. Kyber KEM is designed to cope with this thru providing quantum outside safety. However, its effectiveness can be hampered if it remains vulnerable to assault with the resource of time. Mitigating those assaults ensures the long-term safety of Kyber KEM as we transition proper into a quantum future.

How do we mitigate the timing attack? 

Here are some number one techniques to mitigate timing attacks and shield Kyber KEM: 

  1. Time manipulate

    This is the primary protection. Cryptographic libraries and Kyber KEM implementations need to be designed to resist temporal leaks. This includes ensuring a everlasting timeout in desire to private keys.

  2. Randomness

    Introducing randomness into cryptographic operations can similarly masks temporal variability and make it tough to put into effect. This can be performed thru:

    • Random padding

      Adding random facts earlier than the input is processed can masks the real records getting used and prevent attackers from preserving aside the effect of a non-public key throughout processing.

    • Random branching

      Instead of deterministic branching statements (if-else) that may have barely distinctive processing times depending on the input, introduce randomness to pick which branch to execute first This enables cast off the temporal variability related to specific branches a number of the is removed.

  3. Safe Coding Practices

    Developers need to apprehend even as it is able to interfere and code Kyber KEM implementations with security in thoughts. This consists of strategies that may introduce random time changes primarily based at the private key.

  4. Hardware-based protection features

    Sometimes special hardware designed to face up to factor channel attacks may be used. These hardware answers can offer extra safety towards timing attacks thru software program program-based mitigation techniques.

  5. Research and evaluation

    While no longer an ideal answer, enforcing a monitoring system that may perceive suspicious patterns all through execution can help find out capability timing assaults this lets in a few aspect fast is determined.


In end, timing assaults severely threaten the Post-Quantum Kyber Key Encapsulation Mechanism (KEM) and exceptional cryptographic schemes. These assaults use diffused changes in processing time to guess touchy records, probably compromising the safety of encrypted information. 

The vulnerability posed with the useful resource of time assaults highlights the significance of imposing strong safety functions to combat such threats. Techniques which incorporates time-saving implementation, randomization strategies, stable code practices, and hardware-based totally safety can assist pork up cryptographic structures against time attacks 

Furthermore, continuous surveillance and surveillance is vital to discover capacity attacks in time and reply straight away. By addressing those vulnerabilities and imposing powerful mitigation strategies, we can shield cryptographic structures which includes Kyber KEM and keep the integrity and confidentiality of our encrypted communications inside the Nineties, in particular inside the face of evolving threats along side quantum computing and advanced adversaries. 

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About the Author

Aditi Goel is consultant at Encryption Consulting. Her main focus revolves around PKI-As-A-Service initiatives (PKIs) and cloud services. Leveraging her knowledge of PKIs, HSM, CLM and Code Signing to develop solution for our clients. She ensures that the clients receive customized strategies that fit their needs perfectly.

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