Recently I had a problem with a very large file I downloaded and wanted to have an alternative option to re-downloading it. The checksum of the file with the problem was incorrect. So I decided to look for ways to compute the MD5 checksums for parts of the file.
How to read a part of the file?
dd if=<filename> skip=<number of blocks> bs=<block size> count=<no of blocks>
I found this solution on stackoverflow.com
So, to read a file from byte 1025 to byte 4096,
dd if=lorem_ipsum.txt skip=1024 bs=1 count=3072
Now for the md5sum...
dd if=lorem_ipsum.txt skip=1024 bs=1 count=3072 | md5sum