Secure Email Communication between Alice and BobSetup:Alice and Bob each have their own pair of cryptographic keys: a private key and a public key.They both use email clients that support digital signatures.Sending an Email:Alice wants to send a confidential email to Bob.Before sending the email, Alice digitally signs the email using her private key. This process involves generating a hash of the email content and encrypting it with her private key to create the digital signature.Alice then attaches the digital signature to the email.Receiving the Email:Bob receives the email from Alice.Along with the email content, Bob also receives the digital signature attached by Alice.Verification:Bob's email client automatically verifies the digital signature using Alice's public key. It decrypts the digital signature to obtain the hash of the original email content.Meanwhile, Bob's email client independently calculates the hash of the received email content.If the calculated hash matches the decrypted hash from the digital signature, Bob's email client confirms that the email is authentic and unaltered.Outcome:Bob can trust that the email originated from Alice and hasn't been tampered with during transmission.Since Alice's private key was used to sign the email, she cannot deny sending it. This provides non-repudiation.If the verification fails (e.g., if the email content has been altered or if the digital signature is invalid), Bob's email client alerts him about potential tampering or forgery.In this scenario, digital signatures ensure the confidentiality, integrity, authenticity, and non-repudiation of the email communication between Alice and Bob, even over untrusted networks like the internet.