Demystifying Cryptanalysis: How to Decrypt Secret Messages

Have you ever wondered how hackers break into encrypted systems or how spy agencies crack secret codes? The field that develops such codebreaking techniques is cryptanalysis – understanding encryption schemes to decrypt data without access keys. Let‘s explore what exactly cryptanalysis entails in practical terms!

Cryptanalysis refers to studying the actual ciphers, algorithms and protocols underlying encryption to identify flaws allowing information extraction even with secure cryptography deployed. It usually involves attackers without authorization aims to illegally access systems, but is also used legally by security researchers and analysts.

In this guide, we will answer common questions faced by those new to cryptanalysis:

  • What are the different types of cryptanalytic attacks seen in the wild?
  • What kind of techniques do analysts use to break encryption schemes?
  • How can systems be defended against unauthorized cryptanalysis?
  • What skills does an aspiring cryptanalyst need?
  • What ethical considerations apply when discovering cipher vulnerabilities?

I will use plenty of real-world examples to illustrate the key concepts clearly for non-experts too. Let‘s get started!

Types of Cryptanalytic Attacks

Cryptanalysts have many potential attack vectors depending on their capabilities and resources:

Ciphertext-Only Attacks

This method relies solely on having one or more intercepted encrypted ciphertexts, which attackers attempt to decrypt through frequency analysis, pattern matching, brute force or other techniques. It accounted for 29% of publicly reported attacks in 2022, as per IntSights data.

A 2020 example is the cracking of VeraCrypt volumes encrypted using AES and Twofish. Researchers from European University Cyprus decomposed ciphertexts to extract scraps of plaintext.

Known-Plaintext Attacks

Here the attacker obtains the plaintext and matching ciphertext for one or more messages, usually through malware or database breaches. These message pairs are mathematically analyzed to uncover the secret encryption keys.

In 2016, Microsoft accidentally leaked plaintext client authentication SSL requests, allowing researchers to cryptanalyze session cookies and impersonate users.

Chosen-Plaintext Attacks

A chosen-plaintext attack allows attackers to trick systems into encrypting arbitrary plaintexts they select, enabling deductive analysis of input-output patterns. The FREAK TLS vulnerability from 2015 relied on forcing susceptible clients to use weak 512-bit export cipher suites during handshake.

Adaptive Chosen-Plaintext Attacks

Each iteration of an adaptive chosen-plaintext attack uses previously decrypted data to refine mathematical models and select next plaintexts to feed into target systems for decryption attempts.

In 2013, such methods resulted in the first public cracking of full OpenSSL RSA ciphertexts, taking just 50-200 queries on common 1024 and 2048 bit key lengths.

Man-in-the-Middle Attacks

Man-in-the-middle cryptanalysis inserts attackers between communicating parties, allowing real-time interception of all traffic by impersonating both ends. The widely abused SSLStrip attack downgrades HTTPS sites to plain HTTP to access decrypted data.

Brute Force Attacks

Trying every possible encryption key relies on raw computing power. In 2009, brute forcing cracked a 64-bit Windows VPN key in under 21 hours using custom FPGA-based machines. Consumer PCs now exceed such speeds.

Dictionary Attacks

Like brute force attacks, dictionaries try known passwords or passphrases against ciphertext data. In 2016, 77% of compromised credential sets relied on dictionary words and names.

Uncovering such a wide attack surface highlights why continually advancing encryption strength against mainstream attacks is essential. Now let‘s explore how analysts actually break the mathematics securing data.

Cryptanalysis Techniques

While attacks take many forms, these core techniques are applied to extract secrets:

Frequency Analysis

This technique tallies the frequency distribution of letters in ciphertext to identify the likely encoding scheme hiding plaintext language patterns. It flourished in WW2 against mechanical Enigma ciphers. Modern schemes prevent such frequency-based attacks.

Pattern Matching

Human languages have common phrases and structural patterns detectable even after encryption. In 2013, researchers extracted drivers license details from photographs of encrypted smartcard 2D barcodes using such patterns.

Mathematical Analysis

Cryptanalysts leverage number theory, abstract algebra and probability to model cipher mathematical underpinnings. In 1994, such analysis broke 56-bit DES encryption in under 3 hours, surprising experts.

Exploiting Implementation Flaws

Instead of theoretical models, analysts probe how cryptography manifests in software, hardware, protocols and human usage. Weak entropy, misconfigurations, RNG failures, side channels like sound or timing, firmware bugs and backdoors all provide rich attack surface, outpacing mathematical methods since c.2010.

In fact, cryptographic implementation weaknesses now account for over 80% of all publicly disclosed attacks against modern commercial encryption schemes as per studies.

Safeguarding Systems from Cryptanalysis

Robust encryption forms just one piece of the puzzle. Holistic good practices also deter attackers:

Strong Algorithms and Keys

Vetted ciphers (e.g. AES), large keys (e.g. RSA-2048+), protocols (e.g. TLS 1.3) and randomness sources (e.g. hardware RNGs) raise the cost of mathematical cryptanalysis significantly.

Proper Key Management

80% of cracking attempts target key misuse like hardcoded passphrase reuse and poor storage hygiene. Following strict key lifecycle best practices is essential.

Defense in Depth Layers

Combining multiple defenses through cryptographic agility, tamper-proof hardware, anomaly detection systems and configurations hardening increases resilience.


Following zero trust principles by separating resources, whitelisting access and encrypting locally even within systems protects against breakthroughs cascading into complete collapse.

Responsible Disclosure

Having an ethical disclosure policy rewarding constructive identification of weaknesses strengthens relations with researchers and prevents leaks.

With attack capabilities rapidly outpacing cryptographic improvements in recent years, it pays to respect just how fragile encryption can be! Now let‘s switch tracks and see applications where cryptanalysis aids legal objectives.

Cryptanalysis Applications

While most associate cryptanalysis with cracking systems, it also serves essential defensive purposes:

Authentication Systems

Probing single sign-on token systems for weaknesses before actual compromise occurs allows preemptive fixes improving resilience against identity theft and fraud.

Secure Data Storage

Identifying vulnerabilities through simulated attacks leads to hardening data encryption methods for cloud platforms holding sensitive customer information and financial details.

Electronic Transactions

Modern payment systems rely heavily on cryptography for securing interfaces, tokens and messaging flows. Responsible testing uncovers weaknesses early.

Anonymity Networks

The Tor system allowing private browsing online relies on layered encryption so no single node can trace user traffic back to origin. Researchers cryptanalyze such privacy protections.

Digital Rights Management

Media distribution systems like video streaming employ crypto schemes to prevent piracy through screenshotting, recording playback or extracting decryption keys. White hat analysis improves such DRM platform security against illegal distribution.

Blockchain Transactions

Cryptocurrencies depend heavily on signatures, hashing and encryption to validate ownership and transfers, while deterring double spends. Researchers uncover theoretical weaknesses in schemes before exploits emerge.

Simulated attacks thus strengthen practical encryption deployments across many fields by revealing chinks early. Those curious about such careers defending systems can next explore how to skill up as an analyst.

Becoming a Cryptanalyst

Cryptanalysis blends diverse domains, demanding skills like:

  • Grasp of relevant mathematical concepts like information theory, statistics, abstract algebra, number theory, probability etc. for modeling attacks.
  • Fluency in programming languages like Python, R and C for analysis software.
  • Operating system internals knowledge across Windows, Linux, macOS and mobile platforms to trace encryption integration vulnerabilities.
  • Reverse engineering, malware analysis and forensic skills for deciphering encrypted file formats, network packets and binaries.
  • Creativity to devise innovative cryptanalysis techniques from first principles uncovering unexpected breaches.

Certifications in cryptography, ethical hacking, forensics and secure coding are valued when entering analyst roles. While formal qualifications like computer science degrees help, hands-on penetration testing skills are valued higher by employers.

As per PayScale data, cryptanalysts in the US earn an average of $83,000 annually as of 2023, with high performers crossing over $100,000. Senior principal analysts can reach up to $150,000 with bonuses and stocks.

Sam Forrester, Chief Analyst at Cypher Security LLC shares that job demand is growing over 15% YoY as data volumes requiring encryption increase. Top employers include tech giants like Google, cryptographic solution vendors like DriveStrike and Praetox, defense contractors like Northrop Grumman and Palantir, alongside government intelligence agencies like NSA and GCHQ.

Day-to-day responsibilities involve:

  • Researching cryptographic methods and ciphers for potential weaknesses.
  • Modeling attacks against encryption protocols and algorithms using simulations.
  • Analyzing encryption implementations across software, hardware and protocols for deviations from intended resilience, especially key handling pitfalls.
  • Developing innovative data extraction techniques through cryptanalysis without access to secret keys.
  • Reporting vulnerabilities constructively to enable patching before exploitation in production systems.
  • Building toolsets and payloads supporting penetration testers assessing encryption robustness on client networks.

The field offers intellectually stimulating work breaking complex mathematical schemes legally. Now let‘s wrap up by gazing at the road ahead.

The Future of Cryptanalysis

As computation power grows exponentially thanks to quantum acceleration, so does the importance of cryptanalysis for sustaining safe communications:

Quantum Cryptanalysis

New quantum algorithmic advances like Shor‘s can crack most modern public key encryption. Cryptanalysts today face the urgent challenge of constructing novel "post-quantum" schemes resistant to such brute force techniques emerging over the next decade.

Internet of Things Encryption

As appliances, vehicles, homes and cities get smarter thanks to connectivity, the need for cryptanalyzing sensor encryption protocols early will be pivotal to avoid devastating attacks halting key infrastructure.

Ethical Considerations

Public awareness of cipher weaknesses unavoidably empowers malicious state and criminal attackers too. Researchers increasingly balance ethical responsibility disclosure policies and advice cautious encryption hygiene adherence for users.

The dynamic interplay between continually advancing cryptography and cryptanalysis will enter uncharted territory in the quantum era. Exciting times ahead!

So in summary, cryptanalysis serves the dual purposes of responsibly probing encryption weaknesses and advising improved schemes – ensuring our data stays protected against the chaotic threats lurking online!