Podcast
Questions and Answers
In the context of side-channel analysis, what fundamentally constitutes 'leakage' from an electronic device?
In the context of side-channel analysis, what fundamentally constitutes 'leakage' from an electronic device?
- The direct observation of memory addresses and register values during active cryptographic operations.
- The measured variations in the execution time of cryptographic algorithms due to processor load.
- Any observable correlation between the state of data manipulated within the device and a physical characteristic of the device's operation, which can be exploited by an adversary. (correct)
- The unintentional emission of electromagnetic radiation that directly reveals the encryption key.
Which of the following is the MOST accurate definition of a Simple Power Analysis (SPA) attack?
Which of the following is the MOST accurate definition of a Simple Power Analysis (SPA) attack?
- A side-channel attack that makes direct interpretations about the operations being performed by a device based on visual inspection of one, or very few, power consumption measurements. (correct)
- A side-channel attack that involves statistically analysing a large number of power traces to identify correlations between power consumption and data processed within a cryptographic device.
- An attack which utilises advanced signal processing techniques to isolate, amplify, and analyse faint electromagnetic emanations to determine the cryptographic key.
- An attack that uses complex mathematical models, like the Hamming weight model, to predict power consumption based on known encryption keys.
During a Simple Power Analysis (SPA) attack on an RSA implementation, an attacker observes a repeating pattern of 'square-and-multiply' operations. Which of the following can the attacker MOST likely determine?
During a Simple Power Analysis (SPA) attack on an RSA implementation, an attacker observes a repeating pattern of 'square-and-multiply' operations. Which of the following can the attacker MOST likely determine?
- The exact sequence of modular exponentiations performed during the RSA operation; information to deduce the private exponent bits. (correct)
- The memory addresses accessed during the RSA operation, revealing the location of the stored private key.
- The precise prime factors, $p$ and $q$, used to generate the RSA modulus $N$, enabling immediate key recovery.
- The precise power consumption of individual transistors within the crypto module.
In the context of RSA exponentiation, which implementation detail presents a potential side-channel vulnerability that an attacker could exploit?
In the context of RSA exponentiation, which implementation detail presents a potential side-channel vulnerability that an attacker could exploit?
What is the primary objective of a Differential Power Analysis (DPA) attack?
What is the primary objective of a Differential Power Analysis (DPA) attack?
In the context of Differential Power Analysis (DPA), what is meant by a 'leakage model'?
In the context of Differential Power Analysis (DPA), what is meant by a 'leakage model'?
In a Correlation Power Analysis (CPA) attack, an attacker correlates predicted power consumption values, derived from a leakage model, with actual power traces acquired from a cryptographic device. Which statistical metric is MOST commonly used to measure this correlation?
In a Correlation Power Analysis (CPA) attack, an attacker correlates predicted power consumption values, derived from a leakage model, with actual power traces acquired from a cryptographic device. Which statistical metric is MOST commonly used to measure this correlation?
During a Differential Power Analysis (DPA) attack against an AES implementation, an attacker aims to target the output of the SubBytes transformation in the first round. What property should be considered when selecting this intermediate value?
During a Differential Power Analysis (DPA) attack against an AES implementation, an attacker aims to target the output of the SubBytes transformation in the first round. What property should be considered when selecting this intermediate value?
Considering a DPA attack scenario, which of the following serves as the MOST compelling rationale for targeting an intermediate value immediately prior to a non-linear transformation (such as an S-box)?
Considering a DPA attack scenario, which of the following serves as the MOST compelling rationale for targeting an intermediate value immediately prior to a non-linear transformation (such as an S-box)?
When executing a Differential Power Analysis (DPA) attack, what impact does increasing the number of power traces have on the success of the attack?
When executing a Differential Power Analysis (DPA) attack, what impact does increasing the number of power traces have on the success of the attack?
In the context of side-channel analysis, what is the difference between masking and hiding countermeasures?
In the context of side-channel analysis, what is the difference between masking and hiding countermeasures?
Consider a cryptographic implementation protected against side-channel attacks using Boolean masking. If $x$ represents the sensitive intermediate variable and $r_1, r_2, r_3$ are random masks, which of the following expressions correctly implements a second-order Boolean masking scheme?
Consider a cryptographic implementation protected against side-channel attacks using Boolean masking. If $x$ represents the sensitive intermediate variable and $r_1, r_2, r_3$ are random masks, which of the following expressions correctly implements a second-order Boolean masking scheme?
Which countermeasure technique is MOST effective at the transistor level to mitigate side-channel leakage?
Which countermeasure technique is MOST effective at the transistor level to mitigate side-channel leakage?
How does algorithmic randomization, as a countermeasure against side-channel attacks, operate?
How does algorithmic randomization, as a countermeasure against side-channel attacks, operate?
Which of the following countermeasures is MOST likely to protect against side-channel attacks at the protocol level?
Which of the following countermeasures is MOST likely to protect against side-channel attacks at the protocol level?
In a masked implementation, a sensitive variable $x$ is masked with a random value $r$, resulting in $x \oplus r$. If an attacker performs a first-order DPA attack, to what extent will this masking likely prevent the attacker from extracting information?
In a masked implementation, a sensitive variable $x$ is masked with a random value $r$, resulting in $x \oplus r$. If an attacker performs a first-order DPA attack, to what extent will this masking likely prevent the attacker from extracting information?
What distinguishes a collision attack from a standard statistical Differential Power Analysis (DPA) attack?
What distinguishes a collision attack from a standard statistical Differential Power Analysis (DPA) attack?
Which of the following is a characteristic feature of horizontal attacks compared to vertical Simple Power Analysis (SPA) and Differential Power Analysis (DPA) techniques?
Which of the following is a characteristic feature of horizontal attacks compared to vertical Simple Power Analysis (SPA) and Differential Power Analysis (DPA) techniques?
Under what condition might a hardware implementation utilize 'dummy operations' as a countermeasure against side-channel analysis?
Under what condition might a hardware implementation utilize 'dummy operations' as a countermeasure against side-channel analysis?
If an engineer aims to safeguard an AES implementation against Differential Power Analysis (DPA) employing a correlation-based distinguisher, which choice will be MOST efficacious in reducing sensitivity to power analysis?
If an engineer aims to safeguard an AES implementation against Differential Power Analysis (DPA) employing a correlation-based distinguisher, which choice will be MOST efficacious in reducing sensitivity to power analysis?
Flashcards
What is Leakage?
What is Leakage?
An observable relationship between a device's value manipulation and a side channel controlled by an adversary.
Simple Power Analysis (SPA)
Simple Power Analysis (SPA)
Attacks based on analyzing one or a few power consumption measurements to discover data-dependent operations.
SPA on Symmetric Algorithms
SPA on Symmetric Algorithms
The number of rounds reveals the key length of the symmetric algorithm.
SPA on Asymmetric Algorithms
SPA on Asymmetric Algorithms
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Collision Attacks
Collision Attacks
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Differential Power Analysis (DPA)
Differential Power Analysis (DPA)
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Target Intermediate Value
Target Intermediate Value
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Leakage Model
Leakage Model
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Side-Channel Distinguisher
Side-Channel Distinguisher
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Side-Channel Countermeasures
Side-Channel Countermeasures
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Masking
Masking
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Hiding
Hiding
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Study Notes
Introduction to Side Channel Attacks
- Side channel attacks is presented by Ileana Buhan in March 2024
Leakage
- Leakage refers to any observable link between the value manipulated by a device and a side channel controlled by an adversary, specifically for electronic devices
Simple Attacks (SPA)
- Simple Power Analysis attacks are based on one or a few measurements
- Used to discover data or instruction dependent operations
- Symmetric attacks use the number of rounds determining the key length
- Symmetric attacks use number of memory accesses
- Asymmetric attacks target the key (ECC/RSA)
- Implementation details of asymmetric attacks include vannila RSA and RSA-CRT
- Key length is a target of asymmetric attacks
- Simple power analysis can be used to determine the PIN verification attempt of a device
- An SPA attack of RSA can visually display the secret exponent using power traces
SPA Attack Summary
- SPA attacks are not simple, and require detailed knowledge about the implementation
- An advanced option is called collision attacks
- Protecting against RSA means sticking to regularity in computation
- The advanced form of SPA attacks today is called horizontal attacks
- SPA attacks are used to enable more complex physical attacks
Collision Attack
- Colliding values can reduce the values to possible keys
Differential Attacks (DPA)
- DPA attacks exploit the data dependency of power consumption for cryptographic devices
- DPA uses a large number of traces to analyze the power consumption at a fixed moment
- The moment in time refers to the function of the processed data
- The steps include choosing the target intermediate value
- Measure traces, known plaintext or ciphertext
- Calculate hypothetical intermediate values
- Choose the leakage model
- Recover key using a side channel distinguisher
- A good intermediate value for block ciphers include S-box out and round-out
Steps of Differential Power Analysis
- Determine the target intermediate value: V(i,j) = f(k(i), m(j))
- Measure power traces with alignment
- Calculate hypothetical intermediate values from known possible values
- Map intermediate values to power values by measuring Leakage Model
- Compares intermediate value power traces
DPA Attack Summary
- Choice of leakage model is key to a successful attack
- Includes choice of distinguisher
- The most powerful distinguisher is the Correlation Coefficient
- The most intuitive distinguisher is the Difference of Means (DOM)
- Includes DPA vs CPA
- Security order is an unprotected implementation and univariate
Countermeasures
- Include special logic styles at the transistor level (WDDL, SABL)
- Platform level countermeasures include redundancy, adding jitter, and noise
- Program level includes dummy instructions and randomized order
- Algorithmic level depends on algebraic operations
- Protocol level involves key usage limits and session keys
- Masking includes a random mask concealing every intermediate value
- Power consumption depends on masked values and not actual values; masking is algorithmic
- Hiding involves making power consumption independent of the intermediate values and operations, uniform, or randomized
- Examples include special logic styles, randomization in time domain, and lowering SNR
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