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You can't retrieve the original text because information is lost in the process and many inputs hash to the same value. However, if the range of inputs is relatively limited, you can try hashing inputs until you find the right hash (see rainbow tables for discovering user passwords from the hash value).

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>many inputs hash to the same value

?

The chances of a sha256 collision is essentially zero barring a vulnerability being found in sha2. Far more likely for a comet to wipe out earth in your lifetime.

Chances of practically finding a collision are indeed really small, though as you can easily calculate, there exists a sha256 hash value such that there are at least 2^256 different 512-bit long bit strings that map to it (and actually most of them should have this property).

> The chances of a sha256 collision is essentially zero barring a vulnerability being found in sha2.

Yes, but to answer the question if you can find the input from the hash, the answer is no because it's impossible to be 100% certain as many input can hash to the same value.

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