The concept of encryption is ancient, with early examples dating back to around 1900 BCE in Egypt. However, the more familiar practice of letter substitution and transposition (rearranging the order of letters) emerged around the time of Julius Caesar, who used a simple substitution cypher to communicate confidential military information. Complex encryption techniques evolved, such as the Vigenère cypher in the 16th century, which used various Caesar cyphers in sequence.
Symmetric and asymmetric encryption
- Symmetric encryption
Symmetric or secret key encryptions use a single secret key shared between and decrypt the message. Common symmetric encryption algorithms include Advanced Encryption Standard (AES), which governments and businesses use due to its high level of security, and Triple Data Encryption Standard (3DES), which has been commonly used in the financial industry for many years.
While symmetric encryption is highly secure, the challenge lies in securely exchanging the secret key between sender and receiver without being intercepted by malicious actors. This is typically achieved through a secure key exchange protocol, such as the Diffie-Hellman key exchange, in which two parties exchange a secret key over an insecure channel.
- Asymmetric encryption
Asymmetric encryption, also known as public-key encryption, solves the key exchange problem by using a pair of keys for each user: public and private keys. Anyone encrypts a message using the recipient’s public key, but only the recipient decrypts it using their private key, which is kept secure and never shared. This type of encryption is fundamental to many internet security applications, including secure email (e.g., Pretty Good Privacy or PGP), safe web browsing (HTTPS), and digital signatures, which verify the authenticity and integrity of a digital message or data file.
Encryption in everyday life
Encryption is everywhere and plays a vital role in protecting our privacy and security online.
- Secure messaging apps
What is a private note? End-to-end encryption (E2EE) is secure communication that only allows the sender and intended recipient(s) to read the messages. This technology is used by popular messaging apps like WhatsApp, Signal, and Privatenote, ensuring that messages, photos, videos, and voice calls are encrypted from one device to another, preventing anyone else, including the service provider, from accessing the data.
- Email encryption
Email encryption adds a layer of electronic communications, protecting the content from being read by anyone other than the intended recipient. As mentioned earlier, PGP is a widely used email encryption program. It uses symmetric encryption to ensure secure and private email communication.
- Voice and video calls
Voice and video calling apps also utilize encryption to protect the privacy of conversations. Skype, for example, uses 256-bit AES encryption to secure audio and video calls. In contrast, FaceTime uses encryption protocols to ensure that calls are secure and can be accessed by unauthorized parties.
- Online banking and e-commerce
When you access your banking portal or makefast online, encryption is hard at work protecting sensitive financial information. The transport Layer Security (TLS) predecessor, the Secure Sockets Layer (SSL), is a cryptographic protocol that secures communications over a computer network. They are commonly used in web browsing, email, instant messaging, and voice over IP (VoIP), ensuring that data transmitted between applications remains secure and private.
