Hi! As you are an expert in the domain, do you know if my method to generate personal password seems secure? Typically, instead of memorizing a lot of random p

Hi! As you are an expert in the domain, do you know if my method to generate personal password seems secure? Typically, instead of memorizing a lot of random password, I memorize only one password and for each website I use the password: sha1(password|domainname) Until here nobody give me a clear answer, and therefore I assume it is secure while not any flaw is discovered. And more precisely, I use sha1(password|number|domainname) because, if I fear my password was discovered, I change it by incrementing the number. I would be very grateful if you mind answer my question. Thanks!