Visualize how hash functions map inputs to fixed-length outputs. Explore avalanche effect, collision resistance, and birthday attack probability.
Hash Function Visualizer maps an entered message to the fixed-length digest produced by a selected hash function. It exposes the mapping in hexadecimal form and supports exploring how a small input change can alter many output bits, a property called the avalanche effect. Its collision and birthday-probability views help distinguish digest length from collision security. The common surprise is that equal-length digests reveal neither equal-length inputs nor how similar the original messages were. A hash digest is also not encrypted text that can later be decrypted.
A concrete input and expected output from the current implementation.
Input
Algorithm: SHA-256 Text: abc
Expected output
ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad
The ASCII text "abc" consists of the bytes 61, 62, and 63 in hexadecimal. SHA-256 maps those three bytes to this 256-bit digest, represented by exactly 64 hexadecimal characters.
A cryptographic hash accepts a byte sequence of arbitrary practical length and returns a digest whose length is fixed by the selected function. Repeating the calculation with exactly the same bytes returns the same digest. Changing even one input bit may change many digest bits, so the visualization compares outputs rather than treating nearby messages as nearby numerical values.
Collision analysis asks whether two distinct inputs share one digest. For an ideal n-bit hash with uniformly distributed outputs, k independent inputs have collision probability 1 minus the product of (1 - i/2^n) for i from 0 through k - 1. This birthday-model probability grows substantially around 2^(n/2) inputs, well before all 2^n outputs are exhausted.
Cryptographic hashes are designed so that a small input difference spreads through the resulting digest. The changed bits should not remain confined to one visible region. This avalanche behavior is expected, but one comparison is only an illustration. It is not a statistical test of the function and cannot establish the function's overall security.
No. A digest does not contain a reversible encoding of the input, so the visualizer cannot decrypt it. Guessable inputs can still be tested by hashing candidates and comparing results. General-purpose hashes alone are therefore not appropriate password-storage schemes; password storage normally requires a dedicated password-hashing construction, a unique salt, and an intentionally costly work factor.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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