Hot answers tagged preimage-resistance
SHA256 gives 256 bits, which is 32 bytes, not 64 "characters" (please use the well-defined bits and bytes). When written in hexadecimal notation, you need 64 characters from 0-9a-f, but the length of the hash is 256 bits. Yes, you could invert the hash. Unfortunately, a straightforward lookup table would be too large to store, but you can still do brute ...
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