BRUCE_FE Interview Notes - Complete HTTP vs HTTPS Comparison

Basic Differences Between HTTP and HTTPS

HTTP and HTTPS are web transmission protocols we use every day when browsing the internet, like 'mail carriers' in the network world, responsible for delivering web content to your browser. The biggest difference between them is like the difference between 'postcards' and 'sealed letters':

Simply put, HTTPS is HTTP with a lock added. Technically, it's HTTP with an SSL/TLS encryption layer, like putting bulletproof armor on your network communication, providing triple protection: encrypting communication content, verifying website authenticity, and ensuring data integrity during transmission.

HTTP Security Vulnerabilities

Unencrypted HTTP is like talking loudly on the phone in public places, with multiple security risks:

• 1. Eavesdropping risk: Like writing private messages on postcards in a coffee shop, anyone passing by can see the content
• 2. Man-in-the-middle attack (MITM): Like a mail carrier who can peek at your letters and modify the content before delivery, without your knowledge
• 3. Session hijacking: Like someone stealing your access card and impersonating you to enter and exit buildings, with the system unable to distinguish
• 4. Unable to verify identity: Similar to receiving a call from someone claiming to be from the bank, but you cannot confirm their real identity, possibly a fraud ring
• 5. Lack of data integrity: Like your package being opened and partially replaced during shipping, and you cannot detect it when received

These risks are like writing your bank card password on a sticky note and posting it on a bulletin board, making HTTP unsuitable for transmitting sensitive data such as passwords, credit card numbers, personal privacy information, etc.

HTTPS Encryption Mechanism

HTTPS uses a hybrid encryption system, like double insurance:

1. 1. Asymmetric encryption: Like a locked mailbox - anyone can drop letters (public key), but only those with the key can open it (private key)
2. 2. Symmetric encryption: Like a safe that both parties share a key, fast but requires secure key exchange
3. 3. Digital certificate (X.509 Certificate/SSL certificate): Similar to government-issued ID, issued by trusted certificate authorities (CA), containing website public key and identity information, proving website authenticity
4. 4. Digital signature: Like tamper-evident seals, once data is modified, damage marks will show

HTTPS solves three major security problems through this mechanism:

• 1. Encryption: Data transmission like encrypted letters, even if intercepted, content cannot be read
• 2. Authentication: Ensures the website you're connecting to is indeed the real website, not a phishing site
• 3. Data integrity: Ensures data like sealed packages, not tampered with during transport

TLS/SSL Handshake Process Explained

The HTTPS handshake process is the actual operation of the encryption mechanism mentioned earlier, with each step solving specific security vulnerabilities:

1. 1. Client Hello: 'Hello, I can communicate using these encryption methods' (sending available encryption algorithms)

   → Solves eavesdropping risk, first step in establishing encrypted channel

2. 2. Server Response: 'This is my ID (digital certificate) and public key' (client obtains server public key from certificate)

   → Solves identity verification problem, provides trusted identity proof

3. 3. Certificate Verification: Client checks certificate authenticity, confirms public key indeed belongs to target website

   → Prevents man-in-the-middle attacks, ensures connection to real website not phishing site

4. 4. Key Exchange: Client encrypts a random password with server public key (only server private key can decrypt)

   → Solves eavesdropping risk, ensures key exchange process is not eavesdropped

5. 5. Generate Shared Key: Both parties generate the same session key based on shared random password

   → Solves session hijacking problem, establishes unique encrypted session

6. 6. Start Encrypted Communication: Both parties encrypt all subsequent communication with this shared session key

   → Solves lack of data integrity problem, ensures data transmission process is not tampered with

Note: The client never obtains the server's private key, the server private key remains confidential. The public key is used to securely exchange temporary passwords, after which both parties use this password to derive a symmetric encryption session key.

Client                                            Server
   |                                               |
   |               Client Hello                    |
   |---------------------------------------------->|
   |                                               |
   |           Server Hello, Certificate           |
   |<----------------------------------------------|  ← Client obtains server public key
   |                                               |
   |        Client Key Exchange, Finished          |
   |---------------------------------------------->|  ← Encrypt random password with public key
   |                                               |
   |               Server Finished                 |
   |<----------------------------------------------|
   |                                               |
   |         Encrypted Application Data (HTTP Request/Response)           |
   |<--------------------------------------------->|

Can HTTPS be cracked?

HTTPS security is built on multiple layers of protection, like a castle with multiple lines of defense. But we need to understand its security boundaries:

• 1. Theoretically very secure: The encryption algorithms used by HTTPS are like super complex combination locks, almost impossible to brute force with current computers

  Cracking an HTTPS connection is like digging a mountain with a toothpick, requiring thousands of years

• 2. Practical weaknesses: Attackers usually don't go head-to-head, but look for system vulnerabilities or configuration errors

  Like thieves don't force open the front door, but look for unclosed windows or back doors

  For example: using outdated SSL versions, misconfigured certificates, weak encryption algorithms, or unpatched server vulnerabilities

• 3. Man-in-the-middle attacks: In insecure networks (like public WiFi), someone might pretend to be the website you want to connect to

  But modern browsers will warn like security guards, alerting you to potential fraud

• 4. Certificate trust issues: If the certificate authority (CA) is compromised, it's like the ID card factory being hijacked

  This is why browsers regularly update the list of 'trusted certificate authorities'

• 5. Endpoint security: Even if the transmission process is secure, if your computer is infected, data can still be stolen

  HTTPS only protects data security on the road, cannot protect security at home

• 6. Quantum computing threat: Future supercomputers might crack existing encryption methods

  Like ancient city walls encountering modern artillery, so experts are already developing stronger defenses

Overall, HTTPS's encryption system itself is very robust and unlikely to be directly cracked in the foreseeable future. Most security issues come from human errors or device problems, not HTTPS protocol defects.

HTTPS from SEO Perspective

Search engines (especially Google) are increasingly valuing website security, HTTPS has multiple impacts on SEO:

• 1. Ranking factor: Google clearly states HTTPS is a ranking signal, though with small weight
• 2. Chrome security warning: Non-HTTPS sites marked as 'Not Secure', may increase bounce rate
• 3. HTTP/2 requirement: Utilizing HTTP/2 performance improvements requires HTTPS
• 4. Trust improvement: Secure websites gain more user trust, indirectly improving conversion rates
• 5. Referrer information: HTTPS to HTTP redirects lose referrer information

From an SEO perspective, migrating to HTTPS is a worthwhile investment strategy that ensures websites don't fall behind in search results due to security issues.

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