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The RFC2617 says to encode the username and password to base64 but don't say what character encoding to use when creating the octets for input into the base64 algorithm.
Should I assume US-ASCII or UTF8? Or has someone settled this question somewhere already?
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Basic Authentication sends a Base64 encoded string that contains a user name and password for the client via HTTP headers. Base64 is not a form of encryption and should be considered the same as sending the user name and password in clear text. However, all traffic is encrypted and transmitted over a TLS v1.
Basic authentication is a simple username and password scheme built into the HTTP protocol. Workflows sends HTTP requests with the Authorization header containing the word Basic followed by a space and a base64 encoded string of username:password .
The Base64 encoding, most importantly, ensures that the user:pass characters are all part of the ASCII character set and ASCII encoded. A user:pass in HTTP Basic auth is part of the Authorization header-field value. HTTP header values are ASCII (or Extended ASCII) encoded/decoded.
Basic authentication is vulnerable to replay attacks. Because basic authentication does not encrypt user credentials, it is important that traffic always be sent over an encrypted SSL session.
RFC 2617 can be read as "ISO-8859-1" or "undefined". Your choice. It's known that many servers use ISO-8859-1 (like it or not) and will fail when you send something else. So probably the only safe choice is to stick to ASCII.
For more information and a proposal to fix the situation, see the draft "An Encoding Parameter for HTTP Basic Authentication" (which formed the basis for RFC 7617).
Since 2015 there is RFC 7617, which obsoletes RFC 2617. In contrast to the old RFC, the new RFC explicitly defines the character encoding to be used for username and password.
charset="UTF-8" in its challenge, like this:WWW-Authenticate: Basic realm="myChosenRealm", charset="UTF-8"Complete version:
Read the spec. It contains additional details, such as the exact encoding procedure, and the list of Unicode codepoints that should be supported.
As of 2018, modern browsers will usually default to UTF-8 if a user enters non-ASCII characters for username or password (even if the server does not use the charset parameter).
The realm parameter still only supports ASCII characters even in RFC 7617.
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