
Basic access authentication

In the context of an HTTP transaction, basic access authentication is a method for an HTTP user agent (e.g. a web browser) to provide a user name and password when making a request. In basic HTTP authentication, a request contains a header field in the form of codice_1, where credentials is the Base64 encoding of ID and password joined by a single colon codice_2.
It is specified in from 2015, which obsoletes from 1999.
Features.
HTTP Basic authentication (BA) implementation is the simplest technique for enforcing access controls to web resources because it does not require cookies, session identifiers, or login pages; rather, HTTP Basic authentication uses standard fields in the HTTP header.
Security.
The BA mechanism does not provide confidentiality protection for the transmitted credentials. They are merely encoded with Base64 in transit and not encrypted or hashed in any way. Therefore, basic authentication is typically used in conjunction with HTTPS to provide confidentiality.
Because the BA field has to be sent in the header of each HTTP request, the web browser needs to cache credentials for a reasonable period of time to avoid constantly prompting the user for their username and password. Caching policy differs between browsers.
HTTP does not provide a method for a web server to instruct the client to "log out" the user. However, there are a number of methods to clear cached credentials in certain web browsers. One of them is redirecting the user to a URL on the same domain, using credentials that are intentionally incorrect. However, this behavior is inconsistent between various browsers and browser versions. Microsoft Internet Explorer offers a dedicated JavaScript method to clear cached credentials:
<script>document.execCommand('ClearAuthenticationCache');</script>
In modern browsers, cached credentials for basic authentication are typically cleared when clearing browsing history. Most browsers allow users to specifically clear only credentials, though the option may be hard to find, and typically clears credentials for all visited sites.
Protocol.
Server side.
When the server wants the user agent to authenticate itself towards the server, the server must respond appropriately to unauthenticated requests.
To unauthenticated requests, the server should return a response which contains a "HTTP 401 Unauthorized" status line and a "WWW-Authenticate" header field.
The "WWW-Authenticate" header field for basic authentication is constructed as following:
codice_3
The server may choose to include the "charset" parameter from :
codice_4
This parameter indicates that the server expects the client to use UTF-8 for encoding username and password (see below).
Client side.
When the user agent wants to send authentication credentials to the server, it may use the "Authorization" header field.
The "Authorization" header field is constructed as follows:
For example, if the browser uses codice_5 as the username and codice_6 as the password, then the field's value is the Base64 encoding of codice_7, or codice_8. Then the codice_9 header field will appear as:
codice_10