As many organizations move away from paper documents to digital documents, digital signatures are required to manage any sensitive digital documents. Digital signatures can be used to authenticate the source of the message, such that the receiver can decide whether to trust the sender or not. Now-a-days it is most widely used for software distribution and financial transactions.
In public key cryptography, it is possible to use a private key to sign a file. Anyone who has the corresponding public key can check whether the file was signed by the private key. Anyone who doesn’t have the private key cannot forge such a signature.