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Jagan
Jagan

Reputation: 4887

How does HTTPS provide security?

I want to know how HTTPS is implemented. Whether the data is encrypted or path is encrypted (through which data is passed). I will be thankful if someone provides me implementation details.

Upvotes: 45

Views: 52575

Answers (5)

Richard H
Richard H

Reputation: 39055

Very simply, HTTPS uses Secure Socket Layer to encrypt data that is transferred between client and server. SSL uses the RSA algorithm https://en.wikipedia.org/wiki/RSA_(cryptosystem), an asymmetric encryption technology. The precise details of how the algorithm works is complex, but basically it leverages the fact that whilst multiplying two large prime numbers together is easy, factoring the result back into the constituent primes is very, very hard. How all SSL/RSA encryption works is:

The server generates two large prime numbers, and multiplies them together. This is called the "public key". This key is made available to any client which wishes to transmit data securely to the server. The client uses this "public key" to encrypt data it wishes to send. Now because this is an asymmetric algorithm, the public key cannot be used to decrypt the transmitted data, only encrypt it. In order to decrypt, you need the original prime numbers, and only the server has these (the "private key"). On receiving the encrypted data, the server uses its private key to decrypt the transmission.

In the case of you browsing the web, your browser gives the server its public key. The server uses this key to encrypt data to be sent to your browser, which then uses its private key to decrypt.

So yes all data transmitted to/from server over HTTPs is encrypted - and encrypted well. Typical SSL implementations use 128 or 256 digits for their keys. To break this you need a truly vast amount of computing resources.

As far as I am aware the request for a server asset is not encrypted - use httpfox https://addons.mozilla.org/en-US/firefox/addon/6647/ or Wireshark http://www.wireshark.org/ or something to confirm.

Upvotes: 89

AntonK
AntonK

Reputation: 2310

I thought this was a really concise human readable explanation: http://robertheaton.com/2014/03/27/how-does-https-actually-work/

Here is my summarised version:

Concepts:

  • Asymmetric cryptography algorithm – Public key encryption, private key decryption.
  • Symmetric cryptography algorithm – Public key encryption and decryption.

Handshake:

  1. Hello – Client send cryptography algorithm and the SSL version it supports.
  2. Certificate Exchange – Server sends certificate to identify itself, and certificate public key.
  3. Key Exchange – The client uses Certificate public key to encrypt a new client regenerated public key (using the agreed asymmetric cryptography algorithm from step 1) and sends it to the server. The server decrypts it using its private key (using asymmetric cryptography algorithm).
  4. Data Exchange - This public key is now know by both client and server. It is used for subsequent requests/responses for both encryption and decryption on both client and server (symmetric cryptography algorithm)

Upvotes: 10

Klaus Byskov Pedersen
Klaus Byskov Pedersen

Reputation: 120937

You can read all the details in the TLSv1 RFC-2246.

For security analysis, specifically the following section:

F. Security analysis

The TLS protocol is designed to establish a secure connection between a client and a server communicating over an insecure channel. This document makes several traditional assumptions, including that attackers have substantial computational resources and cannot obtain secret information from sources outside the protocol. Attackers are assumed to have the ability to capture, modify, delete, replay, and otherwise tamper with messages sent over the communication channel. This appendix outlines how TLS has been designed to resist a variety of attacks.

further content snipped

Upvotes: 6

Leandro Gomide
Leandro Gomide

Reputation: 1008

Server and client do not have control over the path that is used to transmit the data. The path used is a matter for the network layer (Internet Protocol - IP), not for the Transport Layer Security (TLS)

The data itself is encrypted, and there are also means for checking server autenticity, as mentioned by Noon Silk.

http://en.wikipedia.org/wiki/Transport_Layer_Security

Upvotes: 0

Noon Silk
Noon Silk

Reputation: 55082

In two ways.

  1. By ensuring that all information transmitted between you and the website is encrypted. It does this via a key-exchange process using RSA (which exchanges a 'session key', which is used for the actual encryption).

  2. By (trying to) demonstrate trust in the website you visit. Certificates are provided to domains, and the idea is that on your machine you trust only certificates from various reputable sources. Then, you can (in theory) be assured that when a certificate pops up for "Your Bank", it is really "Your Bank" website, and not some other website. In practice, very few people care/notice this aspect of SSL.

It's transport layer security. It is not application level. You still need to follow secure coding practices and various other techniques to ensure that your site is secure.

Upvotes: 11

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