1 / 14

http Web Authentication

http Web Authentication. Web authentication is used to verify a users identity before allowing access to certain web pages On web browsers you get a login prompt. There are two types of authentication: Basic and Digest. How Basic Authentication Works. GET /protected/index.html HTTP/1.1.

blue
Download Presentation

http Web Authentication

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. http Web Authentication • Web authentication is used to verify a users identity before allowing access to certain web pages • On web browsers you get a login prompt • There are two types of authentication: Basic and Digest

  2. How Basic Authentication Works GET /protected/index.html HTTP/1.1 HTTP/1.1 401 Unauthorized WWW-Authenticate: Basic realm=“Private” Display Login panel GET /protected/index.html HTTP/1.1 Authorization: Basic JAadf0987awe

  3. Problems with Basic Authentication • Passwords are easy to intercept • Passwords are trivial to decrypt • Once you have the password you have access to many documents

  4. How Digest Authentication Works GET /protected/index.html HTTP/1.1 HTTP/1.1 401 Unauthorized WWW-Authenticate: Digest realm=“Private” nonce=“897sgkjhsadAdsiu” Display Login panel GET /protected/index.html HTTP/1.1 Authorization: Digest username=“Alice” realm=“Private” nonce=“897sgkjhsadAdsiu” response=“5ijasd9734kuyasds0g”

  5. Challenge and Response • Challenge (nonce): any changing string • E.g. MD5(IP address:timestamp:server secret) • Response: challenge hashed with the user’s name & password and uri of requested page • MD5(MD5(name:realm:password):nonce:MD5(request)) • Server-specific implementation options • One time nonce • Time-stamped nonce

  6. Digest Advantage over Basic • Password is not transmitted in a way that can be decrypted • Can’t replay the client/server handshake because the nonce changes each time • The intercepted response is valid only for a single web page because the response has the request hashed. • Disadvantages • Few web browser supports it • Shared disadvantages • The document itself can be sniffed!!!

  7. Secure Socket Layer (ssl) • The secure socket layer sandwiches itself between the transport layer and the application layer in the OSI model • The ssl provides: • data encryption • Can the message be snooped? • server authentication • Is the machine your connected to the REAL server? • message integrity • Was the message manipulated between you and the server? • Optionally client authentication (seldom used) • Is the server sending data to a machine that should get the data?

  8. “Are you Bob?” {“Are you Bob?”} Bobs-private-key Decrypt Bob’s Public Key Problem: It’s never a good idea to encrypt anything someone sent you with your private key

  9. “Are you Bob?” hash {“Are you Bob?”} {hash} Bobs-private-key “Are you Bob?” Decrypt Bob’s Public Key hash {“Are you Bob?”} & compare This method is know as a digital signature Problem: Bob is still encrypting something sent to him

  10. Are you bob? Alice, this is bob (random) hash {Alice, this is bob} {hash} Bobs-private-key Decrypt {hash} Bob’s Public key hash {Alice, this is bob} compare Problem: Any one can be Bob. Where did Alice get Bob’s public key?

  11. Certificates • A certificate is a way of sending public keys to end users and assure they actually belong to the sender • They contain • Issuer’s name • Info about the identity for whom the certificate has been signed • Public key of the sender • Some time stamps • A certificate is signed by a certificate authority • Verasign, thwarty, … • Web browsers have the public keys of the certificate authority pre-installed. • So, when a new certificate comes and it can be decrypted with a certificate authorities key, it can be assumed that the certificate authority guarantees the public key of the sender

  12. Hi Hi, I’m bob, bob’s certificate Prove it Decrypt {hash} Bob’s Public key hash {Alice, this is bob} compare Alice, this is bob hash {Alice, this is bob} {hash} Bobs-private-key Ok bob, Here’s a secret {secret} bob’s public key Decrypt {secret} Bob’s private key {Some message, hash{message}} Secret-key Decrypt {message,hash} hash {message} Compare hashs

  13. Advantages of SSL • Confidential session • Server authentication • GUI clues for users • Built into most browsers • Easy to configure on the server • Protocol has been analyzed extensively

  14. Disadvantages of SSL • Users don’t check certificates • Most don’t know what they even mean • Too easy to obtain a certificate • Default settings are terrible • Ssl version 2 in on • Totally insecure ciphers are included in the browsers • Very little use of client-side certificates • Performance hit to the server

More Related