This article is about cryptography. For other uses, see Snowball effect and Avalanche (disambiguation).
In cryptography, the avalanche effect is the desirable property of cryptographic algorithms, typically block ciphers[1] and cryptographic hash functions, wherein if an input is changed slightly (for example, flipping a single bit), the output changes significantly (e.g., half the output bits flip). In the case of high-quality block ciphers, such a small change in either the key or the plaintext should cause a drastic change in the ciphertext. The actual term was first used by Horst Feistel,[1] although the concept dates back to at least Shannon's diffusion.
The SHA-1 hash function exhibits good avalanche effect. When a single bit is changed the hash sum becomes completely different.
If a block cipher or cryptographic hash function does not exhibit the avalanche effect to a significant degree, then it has poor randomization, and thus a cryptanalyst can make predictions about the input, being given only the output. This may be sufficient to partially or completely break the algorithm. Thus, the avalanche effect is a desirable condition from the point of view of the designer of the cryptographic algorithm or device. Failure to incorporate this characteristic leads to the hash function being exposed to attacks including collision attacks, length extension attacks, and preimage attacks.[2]
Constructing a cipher or hash to exhibit a substantial avalanche effect is one of the primary design objectives, and mathematically the construction takes advantage of the butterfly effect.[3] This is why most block ciphers are product ciphers. It is also why hash functions have large data blocks. Both of these features allow small changes to propagate rapidly through iterations of the algorithm, such that every bit of the output should depend on every bit of the input before the algorithm terminates.[citation needed]
^Upadhyay, D., Gaikwad, N., Zaman, M., & Sampalli, S. (2022). Investigating the Avalanche Effect of Various Cryptographically Secure Hash Functions and Hash-Based Applications. IEEE Access, 10, 112472–112486. https://doi.org/10.1109/ACCESS.2022.3215778
^Al-Kuwari, Saif; Davenport, James H.; Bradford, Russell J. (2011). Cryptographic Hash Functions: Recent Design Trends and Security Notions. Inscrypt '10.
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slope conductance of the Zener diode. The Zener effect is distinct from avalanche breakdown. Avalanche breakdown involves minority carrier electrons in...
such diode, but one usually dominates the other. Avalanche diodes are optimized for avalancheeffect, so they exhibit small but significant voltage drop...
killed by an avalanche a year later, or escaping." The idea that the death of one butterfly could eventually have a far-reaching ripple effect on subsequent...
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decorrelation of the generated values is the main feature. Diffusion (and its avalancheeffect) is also applicable to non-cryptographic hash functions. Confusion...
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This is in contrast to cryptographic hashing, which relies on the avalancheeffect of a small change in input value creating a drastic change in output...
overwhelming probability) result in a mostly different hash, due to the avalancheeffect. For example, adding a period to the end of the sentence: MD5("The...
execution, NIST recommends an iteration count of 10,000 or more.: 5.1.1.2 Avalancheeffect Comparison of cryptographic hash functions Cryptographic agility CRYPTREC...
breakdown voltage. This effect is used to regulate voltage (Zener diodes) or to protect circuits from high voltage surges (avalanche diodes). A semiconductor...
phenomenon known as a Townsend avalanche to multiply the effect of the original ionizing event by means of a cascade effect whereby the free electrons are...
that the new hash value appears uncorrelated with the old hash value (avalancheeffect) Fuzzy hashing exists to solve this problem of detecting data that...
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