I read a paper at the time where someone described a tool they made to find a near-collision, they explained they were just flipping bits and visually observing the affects. That sounded kinda fun, but they didn't release it, so I tried to replicate it from their description!
Your tool seems to understand the gist of differential cryptography better though.
You can track a 1-bit change or 3-bit change to "M" and see how it propagates through the SHA256 rounds in your tool.
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So your tool is probably better at understanding the underlying design of SHA2. We know that SHA2 was created well into the era of differential-analysis for example, so the designers would have inevitably done analysis similar to how your tool works.
https://lock.cmpxchg8b.com/sha1/visualize.html
I read a paper at the time where someone described a tool they made to find a near-collision, they explained they were just flipping bits and visually observing the affects. That sounded kinda fun, but they didn't release it, so I tried to replicate it from their description!