Hashing vs. Signing Binaries

Question

If you want to ensure that a file is valid (untampered and came from the correct/expected source), there are two things you can do: hashing, and signing

Answer 1

Hash is a output with fixed length of characters(or bits if represented in binary) for a specific data that is passed into a function. Hash is irreversible.The hash value for a particular data is always same. If a single bit in data changes almost entire hash for the altered data is changed. The process of calculating a hash is called hashing.

In Asymmetric cryptography each communicating party has his own key pair (private key and public key). As name suggest , private key is usually kept secret and public key is shared. These keys are as such in nature that if one is used to encrypt then the only other key pair can decrypt.

To achieve non repudiation(sender cannot deny he sent message) and to Authenticate specific entity to receive data , public key is shared to them so that they can decrypt anything that is encrypted by the sender using the corresponding private key that is with the sender(only with sender i.e secret) But note that confidentiality is week in this example as sender does not know and cannot guarantee if public key was compromised to an unknown.

when private key is used to encrypt a Hash then it becomes a signature and the process is called signing. This achieves Authenticity (that data is coming from a genuine guy as private key is used) and also Integrity is assured because receiver verifies the Hash upon receiving data by decrypting the hash using corresponding public key given to him by sender and then calculating the same hash on his own and matching it.