What are Acoustic Side Channel Attacks (ASCAs)?

What is an Acoustic Side-Channel Attack?
Acoustic Side Channel Attack is a specialized form of SCA.


In August, a groundbreaking research paper, "A Practical Deep Learning-Based Acoustic Side Channel Attack on Keyboards," sent shockwaves through the cybersecurity world. Published by renowned universities and supported by the ethics committee of Durham University, U.K., the paper revealed a chilling truth:

Artificial Intelligence (AI) can decode passwords by analyzing the sound produced by keystrokes.

While Acoustic Side Channel Attacks (ASCA) have been around for decades, the study shed light on how the marriage of A.I. and deep learning has escalated the risks posed by these attacks.

Let's delve into the intricate world of ASCA, shall we?

Understanding ASCA

To grasp the concept of Acoustic Side Channel Attacks, one must first comprehend Side Channel Attacks (SCAs). Here's what you need to know:

What are Side Channel Attacks (SCAs):

SCAs are sophisticated hacking methods that crack cryptographic algorithms by analyzing auxiliary systems used in encryption. These attacks use signals emitted by devices, such as electromagnetic waves, power consumption, and even the sounds from keyboards and printers.

Acoustic Side Channel Attacks (ASCA):

A specialized form of SCA, ASCA focuses on the sound of clicks generated by keyboards to interpret what's being typed, thereby leaking sensitive information.

ASCA is especially menacing because keyboard sounds are readily available and often overlooked. Even as non-mechanical keyboards reduce the sound, technology for accessing and processing acoustics has drastically improved. The ubiquity of laptops with standardized keyboards has further broadened the scope for AI-enabled ASCA.

Historical Context of ASCA

ASCA's roots date back to the 1950s, when acoustic emanations from encryption devices were exploited. The United States National Security Agency (NSA) listed acoustic emanations as a security risk in 1982. The threat intensified with modern technology, bringing more microphones closer to keyboards.

The advent of A.I. and deep learning models have rejuvenated the threat from ASCA, especially since many users remain complacent about the acoustic security of their devices in public spaces.

Accuracy of Acoustic Side-Channel Attacks

Recent research conducted by prestigious universities has given us alarming insights into SCA's accuracy:

Training on Keystrokes:

When trained on keystrokes by a nearby phone, classifiers achieved a staggering 95% accuracy without a language model.

Utilizing Deep Learning Models: On a MacBook Pro, the model reached state-of-the-art accuracy with minimal training data.

Smartphone Microphones and Zoom Calls:

The A.I. model achieved 95% accuracy with smartphone microphones but dropped to 93% with Zoom calls.

Protecting Against ASCAs

While foolproof defense against ASCA remains elusive, there are measures to reduce the threat:

Typing Methods:

Shift from traditional to touch-based typing to lower keystroke recognition chances.

Password Complexity:

Creating robust passwords using a mix of upper- and lower-case letters can stump even deep learning models.

Avoid Predictable Phrases:

Utilizing less recognizable phrases can make predictions harder for A.I. models.

Other types of Side Channel Attacks (SCAs):

Timing Attacks:

Definition: Timing attacks analyze how long it takes for a system to process different inputs. An attacker can infer sensitive information about the system's internal operations by measuring these time differences.

Mitigation: This attack can be mitigated by implementing constant-time algorithms that take the same time to execute, regardless of the input.

Power Analysis Attacks:

Simple Power Analysis (SPA):

Definition: SPA observes the power consumption during cryptographic operations to deduce information.

Mitigation: Use of constant power consumption for all operations.

Differential Power Analysis (DPA):

Definition: DPA involves statistical analysis of power consumption data to extract cryptographic keys.

Mitigation: Implementation of hardware countermeasures like noise generation.

Electromagnetic Attacks:

Definition: These attacks measure the electromagnetic radiation emitted by a device to gain insights into its operations.

Mitigation: Shielding the device using Faraday cages or similar measures.

Cache Attacks:

Definition: Cache attacks exploit how a system's cache memory is accessed and shared between processes to gain unauthorized access to data.

Mitigation: Software techniques like cache partitioning and hardware isolation.

Temperature Attacks:

Definition: By analyzing the heat pattern of a device, these attacks can reveal information about the computations being performed.

Mitigation: Thermal shielding and careful design to minimize information leakage through temperature variations.

Optical Attacks:

Definition: These attacks involve analyzing the visual emanations, such as LEDs on routers or other devices, to infer the data being processed.

Mitigation: Limiting or encrypting visual feedback signals.

Fault Injection Attacks:

Definition: This category includes attacks where the attacker induces system operation faults (such as voltage spikes) to gain unauthorized access or information.

Mitigation: Robust error handling and fault tolerance mechanisms.


Acoustic Side-Channel Attacks represent a fascinating yet troubling intersection of technology and security. Though ASCA is not new, A.I.'s involvement has rekindled concerns and intensified the need for vigilance.

As we tap away at our keyboards, we must remember that our sounds could be the keys to our most guarded secrets. And in the world of cybersecurity, sometimes silence truly is golden.

As the saying goes in cybersecurity, "Trust, but shield." Whether it's power consumption or the clatter of keys, SCAs remind us that sometimes the most innocuous details can unlock the most secured gates.