Http authentication....BASIC:
In the context of an HTTP transaction, basic access authentication is a method for a web browser or other client program to provide a user name and password when making a request.[1]
Before transmission, the user name is appended with a colon and concatenated with the password. The resulting string is encoded with the Base64 algorithm. For example, given the user name 'Aladdin' and password 'open sesame', the string 'Aladdin:open sesame' is Base64 encoded, resulting in 'QWxhZGRpbjpvcGVuIHNlc2FtZQ=='. The Base64-encoded string is transmitted in the HTTP header and decoded by the receiver, resulting in the colon-separated user name and password string.
While encoding the user name and password with the Base64 algorithm makes them unreadable to the unaided eye, they are as easily decoded as they are encoded. Security isnot the intent of the encoding step. Rather, the intent of the encoding is to encode non-HTTP-compatible characters that may be in the user name or password into those that are HTTP-compatible.
One advantage of the basic access authentication is all web browsers support it. Rarely it is used on publicly accessible Internet web sites but may sometimes be used by small, private systems. A later mechanism, digest access authentication, was developed in order to replace the basic access authentication and enable credentials to be passed in a relatively secure manner over an otherwise unsecure channel.
Http authentication.....DIGEST:
Digest access authentication is one of the agreed-upon methods a web server can use to negotiate credentials with a user's web browser. It uses encryption to send the password over the network, which is safer than the Basic access authentication that sends plaintext.
Technically, digest authentication is an application of MD5 cryptographic hashing with usage of nonce values to discourage cryptanalysis. It uses the HTTP protocol.
HTTP digest authentication is designed to be more secure than traditional digest authentication schemes.
Digest access authentication is intended as a security trade-off. It is intended to replace unencrypted HTTP basic access authentication. It is not, however, intended to replace strong authentication protocols, such as public-key or Kerberos authentication.
1. basic认证是把用户和密码通过base64加密后发送给服务器进行验证
2. digest认证则是把服务器响应的401消息里面的特定的值和用户名以及密码结合起来进行不可逆的摘要算法运算得到一个值，然后把用户名和这个摘要值发给服务器，服务通过用户名去 在自己本地找到对应的密码，然后进行同样的摘要运算，再比较这个值是否和客户端发过来的摘要值一样。
TTP协议规范的另一种认证模式是Digest模式，在HTTP1.1时被提出来，它主要是为了解决Basic模式安全问题，用于替代原来的Basic认证模式，Digest认证也是采用challenge/response认证模式，基本的认证流程比较类似，整个过程如下：
①浏览器发送http报文请求一个受保护的资源。
②服务端的web容器将http响应报文的响应码设为401，响应头部比Basic模式复杂，WWW-Authenticate: Digest realm=”myTomcat”,qop="auth",nonce="xxxxxxxxxxx",opaque="xxxxxxxx" 。其中qop的auth表示鉴别方式；nonce是随机字符串；opaque服务端指定的值，客户端需要原值返回。
③浏览器弹出对话框让用户输入用户名和密码，浏览器对用户名、密码、nonce值、HTTP请求方法、被请求资源URI等组合后进行MD5运算，把计算得到的摘要信息发送给服务端。请求头部类似如下，Authorization: Digest username="xxxxx",realm="myTomcat",qop="auth",nonce="xxxxx",uri="xxxx",cnonce="xxxxxx",nc=00000001,response="xxxxxxxxx",opaque="xxxxxxxxx" 。其中username是用户名；cnonce是客户端生成的随机字符串；nc是运行认证的次数；response就是最终计算得到的摘要。
④服务端web容器获取HTTP报文头部相关认证信息，从中获取到username，根据username获取对应的密码，同样对用户名、密码、nonce值、HTTP请求方法、被请求资源URI等组合进行MD5运算，计算结果和response进行比较，如果匹配则认证成功并返回相关资源，否则再执行②，重新进行认证。
⑤以后每次访问都要带上认证头部。
其实通过哈希算法对通信双方身份的认证十分常见，它的好处就是不必把具备密码的信息对外传输，只需将这些密码信息加入一个对方给定的随机值计算哈希值，最后将哈希值传给对方，对方就可以认证你的身份。Digest思想同样采如此，用了一种nonce随机数字符串，双方约好对哪些信息进行哈希运算即可完成双方身份的验证。Digest模式避免了密码在网络上明文传输，提高了安全性，但它仍然存在缺点，例如认证报文被攻击者拦截到攻击者可以获取到资源
本文内容由网友自发贡献，版权归原作者所有，本站不承担相应法律责任。如您发现有涉嫌抄袭侵权的内容，请联系:hwhale#tublm.com(使用前将#替换为@)
