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Entropy

A measure of unpredictability used when generating cryptographic keys, seed phrases, and other random security values.

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Definition

A measure of unpredictability used when generating cryptographic keys, seed phrases, and other random security values.

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Why it matters

Cryptography provides the mathematical foundation for keys, signatures, privacy, integrity, and verification.

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How it works

Cryptographic systems draw entropy from unpredictable sources like hardware thermal noise, mouse movements, or specialized noise generation circuits. This randomness is fed into a pseudo-random number generator (PRNG) to create a high-entropy seed, which is then used to derive cryptographic keys.

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Real-world example

Hardware wallets use dedicated True Random Number Generators (TRNGs) to ensure their entropy levels are mathematically secure.

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Advantages

  • Fundamental to cryptographic security
  • Ensures unpredictability of keys
  • Prevents pattern-based brute force

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Limitations

  • Difficult to verify from the outside
  • Vulnerable to poor implementation in software
  • Low entropy sources lead to weak keys

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Common misconceptions

  • Some think computers can generate true randomness, but they actually rely on external ‘noise’ sources.
  • People often believe that simple user input is sufficient to create high-entropy seeds, but it is rarely enough.
Canonical knowledge ID: glossary:entropy