After reading the OP question I conclude that the OP wants a hashing algorithm (example given: bcrypt).
Well, if you are looking for a hash in classic ASP it's a bit like a desert, not so many lbiraries.
This link however implements a sha1 hash, http://forums.aspfree.com/code-bank-54/asp-classic-sha1-hash-82166.html it has the code (read all comments as well), now you have a portable cross-code implementable hash function.
<%
Dim strPassWord, strHash, salt
salt = "6XBMkpz39m8RFCpwt1Cofzbg1TTIN7yTGzMlayIfy9yBOPgX2zhfXM9X5mqv8HT6"
strPassWord = "secret"
strHash = hex_sha1(strPassWord & salt)
Response.Write("<p><b>strPassWord:</b> " & strPassWord & "</p>")
Response.Write("<p><b>strHash:</b> " & strHash & "</p>")
%>
Expanding to C#, Javascript, Python, ... and so on. So somewhere in the future - when you decide to leave classic ASP behind - you'll find that you are still able to use the stored hashed passwords.