Electronic signatures act as replacements for physical signatures and create a unique fingerprint using cryptographic methods to associate the identity of the user with the content of the document. This is done using mathematical algorithms based on which a private key and a public key are created for each user and/or transaction. When a document is electronically or digitally signed, a hash of the document is created, which is encrypted with the private key. This encrypted data is called a digital signature. A property of a digital signature is that if the document gets altered after signing, the signature becomes invalid.