I am given a network packet whose last 64 bytes (128 hex characters) are the RSA-512 digital signature of the SHA-256 hash of the packet. I take a truncated version of this packet (everything except the last 64 bytes) and calculate the hash myself, which is working fine, however I need a way to get back the hash that generated the signature in the first place
I have tried to do this in Python and have run into problems because I don't have the RSA private key, only the public key and the Digital Signature. What I need is a way to take the public key and signature and get the SHA-256 hash back from that to compare it to the hash I've generated. Is there a way to do this? Any crypto libraries would be fine. I am using hashlib to generate the hash
The original hash was signed with the private key. To get the original hash, you need to decrypt the signature with the public key, not with the private key.
How to get the original hashed input to an RSA digital signature?