Git - how to delete old commits without affecting recent commit's sha-1?

Question

I have huge git repository(binary files) and I want to delete old commits to shrink it's size.

Assume my commit history;

$ git log
g0g0g0 - patch 06
f0f0f0 - patch 05
e0e0e0 - patch 04
d0d0d0 - patch 03
c0c0c0 - patch 02
b0b0b0 - patch 01
aaaaaa - initial empty

And each commits has tag;

$ git tag
tag01 -> b0b0b0
tag02 -> c0c0c0
tag03 -> d0d0d0
tag04 -> e0e0e0
tag05 -> f0f0f0
tag06 -> g0g0g0

Here is what I want;

$ git log
g0g0g0 - patch 06 <- tag06
f0f0f0 - patch 05 <- tag05
e0e0e0 - patch 04 <- tag04
aaaaaa - initial empty

$ git tag
tag01 -> deleted b0b0b0
tag02 -> deleted c0c0c0
tag03 -> deleted d0d0d0
tag04 -> e0e0e0
tag05 -> f0f0f0
tag06 -> g0g0g0

Is it possible to delete old three commits(b0b0b0, c0c0c0, d0d0d0) without changing other commit's sha-1 values(g0g0g0, f0f0f0, e0e0e0)?

Answer 1

No, it's not possible. A commit's parents are used to compute its hash. If any part of the history changes, the commit hash will be different.