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Updated on May 12, 2025
Hypertext Transfer Protocol Secure (HTTPS) keeps you safe online by offering a secure version of HTTP, the protocol used to transfer data between your browser and a website. It uses encryption, authentication, and data integrity to create a secure, trusted connection between users and servers. This is made possible through Transport Layer Security (TLS) or the older Secure Sockets Layer (SSL).
This article breaks down how HTTPS works, its main features, and where it’s used.
Definition and Core Concepts
HTTP (Hypertext Transfer Protocol)
HTTP serves as the backbone of online communication, enabling websites to deliver content such as text, images, and videos to user browsers. However, standard HTTP transmits data as plaintext, making it vulnerable to interception and attacks (e.g., data theft or spoofing). This is where HTTPS steps in, adding a secure layer to HTTP transactions.
TLS (Transport Layer Security) and SSL (Secure Sockets Layer)
TLS is a cryptographic protocol that provides secure communication over a network. It replaced SSL, which was initially used for similar purposes but became outdated due to evolving security standards and discovered vulnerabilities. The evolution has continued with different versions of TLS, with newer versions offering enhanced security over older ones. TLS is the mechanism that encrypts data transmitted via HTTPS, ensuring it remains confidential and tamper-proof.
Encryption
Encryption converts data into unreadable ciphertext that can only be decrypted with the correct cryptographic key. Through encryption, communication between a user’s browser and a server is protected from eavesdroppers and malicious actors.
Authentication
HTTPS relies on digital certificates issued by trusted Certificate Authorities (CAs) to confirm that a website is legitimate. This ensures users are connecting to the intended site rather than a malicious impostor.
Data Integrity
Data integrity ensures that information exchanged between a browser and a website cannot be modified or corrupted during transit. HTTPS uses cryptographic hashing to verify that data remains unchanged.
Port 443
Unlike HTTP, which primarily uses Port 80 for traffic, HTTPS operates on Port 443. This ensures secure communication and helps networks differentiate between secure and unsecured web traffic.
How HTTPS Works
1. Connection Initiation
A secure HTTPS session begins when a user enters a URL starting with “https://” in their browser or clicks on a secure link. This step initiates a request to establish a secure connection with the website’s server.
2. TLS/SSL Handshake
The TLS or SSL handshake is a critical process that establishes a secure connection. It involves the server and the browser exchanging cryptographic information, such as keys and certificates, to authenticate one another. This handshake ensures that both parties agree on the encryption methods to be used.
3. Certificate Exchange
During the handshake, the server sends its digital SSL/TLS certificate to the browser. This certificate includes the website’s public cryptographic key and other identifying details. The browser checks this certificate against trusted Certificate Authorities (CAs) to verify its authenticity.
4. Session Key Generation
If the certificate is valid, both the server and the browser generate temporary session keys used to encrypt and decrypt data for the session. These keys ensure all information shared during the session is secure and private.
5. Encrypted Data Transfer
Once the session keys are established, all subsequent communication between the browser and the server is encrypted. This encryption ensures that sensitive information, such as passwords or credit card details, cannot be intercepted.
6. Connection Closure
When the session ends, the secure connection is terminated. The session keys are discarded, ensuring they cannot be reused or compromised.
Key Features and Components
Encryption
HTTPS encrypts data, making it unreadable to unauthorized parties. This ensures confidentiality and protects sensitive information exchanged online, such as login credentials or payment details.
Authentication
Through the use of SSL/TLS certificates verified by trusted CAs, HTTPS assures users they are connecting to legitimate websites. This prevents attacks like phishing and man-in-the-middle exploits.
Data Integrity
Cryptographic hashing ensures that all data transmitted remains unaltered. Any tampering or corruption is immediately detectable, further safeguarding online communications.
Port 443
By utilizing Port 443, HTTPS differentiates itself from HTTP and ensures secure communication. Firewalls and servers often use this port to identify and manage encrypted traffic.
Certificates
Digital certificates are the backbone of HTTPS authentication. These certificates provide proof of trustworthiness and are crucial for establishing user confidence in secure online transactions.
Use Cases and Applications
E-commerce Websites
Online retailers use HTTPS to protect customer information, such as credit card numbers and personal details. Secure connections encourage trust, giving customers the confidence to shop.
Online Banking
Financial institutions rely heavily on HTTPS to ensure transactions are private and secure. Without HTTPS, financial data could be intercepted by malicious actors.
Social Media Platforms
Social media platforms handle a wealth of personal information, including messages, images, and videos. HTTPS ensures that this data is transmitted securely between users and servers.
Email Services
Email providers use HTTPS to encrypt messages during transit, reducing the risk of data breaches and unauthorized access.
Any Website Handling Sensitive Data
From healthcare portals to government websites, organizations that handle sensitive user data must implement HTTPS to protect their users and comply with regulation standards like GDPR or HIPAA.
Key Terms Appendix
- HTTPS (Hypertext Transfer Protocol Secure): The secure version of HTTP that uses encryption to protect data transfer between browsers and websites.
- HTTP (Hypertext Transfer Protocol): The standard protocol for data communication between browsers and websites, operating without encryption.
- TLS (Transport Layer Security): A cryptographic protocol used to secure internet communications, replacing the older SSL.
- SSL (Secure Sockets Layer): The predecessor of TLS, originally used to encrypt data and now largely obsolete.
- Encryption: The process of converting data into unreadable ciphertext to protect it during transmission.
- Authentication: A process that verifies the identity of a website, ensuring users connect to legitimate servers.
- Certificate: Digital proof issued by Certificate Authorities to validate a website’s trustworthiness and enable secure HTTPS connections.
- Port 443: The standard port used by HTTPS for encrypted web traffic, differentiating it from HTTP’s Port 80.
