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A subsystem or mechanism that provides unpredictable input used to generate random bits for cryptographic operations.
DESCRIPTION
An entropy source supplies randomness to random number generators, critical for secure keys, nonces, and protocols. It may leverage physical phenomena (thermal noise, jitter) or system events to produce unpredictable bits. NIST SP 800-90B defines components and health tests for robust entropy sources. Strong entropy prevents predictable keys and attacks. Implementations combine multiple sources, condition outputs, and monitor quality to maintain security.
ALTERNATIVE DEFINITIONS
NIST
An entropy source contains a noise source, a conditioning component, health tests, and an output interface.
Formalizes the architecture and required components of an entropy source.
Wikipedia
Random number generation may involve a physical process called a hardware random number generator, where the source of randomness is a physical phenomenon.
Highlights physical sources of entropy for hardware RNGs.
RELATED TERMS
Random Number Generator True Random Number Generator NIST SP 800-90B Entropy Pool Seed Nonce /dev/random Timing Jitter Hardware RNG
COMPETING TERMS
Deterministic Random Bit Generator Pseudorandom Number Generator
KNOWLEDGE AREAS
TARGET AUDIENCE
Security Architect Cybersecurity Engineer Hardware Engineer Chief Information Security Officer Software Developer
EXTERNAL SOURCES
- Wikipedia - Random number generation
- NIST - Recommendation for entropy sources
- Linux man-pages - Linux random device documentation
- Cloudflare - Educational article on entropy
TOP QUESTIONS
Why is an Entropy Source vital for security?
Cryptographic keys and nonces require unpredictability. Weak entropy leads to predictable values and compromises security.
Category: Relevancy
What makes a good Entropy Source?
High unpredictability, robustness against bias, health tests, and proper conditioning provide strong random input.
Category: Requirements
What are common mistakes with Entropy Sources?
Relying on insufficient randomness, ignoring health tests, and poor initialization cause weak cryptographic material.
Category: Mistakes
What risks occur if the Entropy Source fails?
Keys become guessable, enabling attacks on encryption and authentication systems. System-wide compromise can follow.
Category: Risks
How do operating systems provide Entropy Sources?
Interfaces like /dev/random and /dev/urandom aggregate entropy from multiple system events and hardware.
Category: Example
How does NIST SP 800-90B influence Entropy Sources?
It defines components, validation, and testing requirements for compliant entropy sources.
Category: Management
Can multiple Entropy Sources be combined?
Yes. Combining sources and conditioning can improve robustness and mitigate single-source weaknesses.
Category: Opinion
Where can I learn more about Entropy Sources?
Read NIST SP 800-90B and OS-level documentation for random devices, then explore hardware RNG references.
Category: Learning
What is a hot topic in Entropy Sources today?
Hardware-based RNGs using trusted modules and robust health monitoring in cloud environments.
Category: Topic