I understand how the digital signature algorithm works. However all the explanations and examples are only about Bob sending a message to Alice.

What i want to know is how digital signature is used in web applications;

  • Such as an ecommerce website
  • Trusting the website to input my credit card info
  • Examples of digital signature during email, from client to ecommerce email(company email)

closed as too broad by Steffen Ullrich, TheJulyPlot, Serge Ballesta, Xander, Steve Jul 10 '17 at 21:01

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • You can use DSA in TLS (for the server certificate and for the certificate chain signatures by CAs). But typically you don't use DSA for those (anymore). The communication of the ecommerce size backend with bank and processors might also use DSA (with or without TLS, but it's also rather uncommon, especially since you need encryption in addition anyway) – eckes Jul 9 '17 at 18:45
  • Are you asking about digital signature algorithms in general or about DSA in particular? Because DSA is only one of several digital signature algorithms and the one which is usually not used today. Instead RSA signatures and ECDSA are used. And as for how these are used in SSL/TLS to secure web applications see How does SSL/TLS work?. – Steffen Ullrich Jul 9 '17 at 19:33
  • Digital signatures are used in many places in the context of your question, like in protecting data transfer using SSL/TLS, protecting mails using S/MIME or PGP, fighting phishing using DKIM signatures, protecting DNS using DNSSec and probably more places. Explaining all of these use cases as you seem to expect makes your question too broad. – Steffen Ullrich Jul 9 '17 at 20:30