48. What is asymmetric encryption?
Asymmetric encryption is also known as asymmetric cryptography. It allows users to encrypt information with so-called shared keys.
An example: you want to send a message to your colleague, but you do not want anyone other than him to see it. This is precisely the purpose of asymmetric encryption.
Very importantly, asymmetric encryption technology is absolutely secure. Even more interesting is that we ourselves come into contact with this type of encryption every day without realizing it. What are we talking about? Do you know a website that starts with “HTTPS”? That’s right 🙂 Here, too, we are dealing with asymmetric encryption.
Asymmetric encryption – definition
The Internet has become an integral part of our lives. Every day we carry out sensitive transactions (e.g. banking transactions ) or chat with friends (e.g. via Messenger ). It is therefore not surprising that individuals or companies need robust security measures to ensure that their data is not compromised online. Asymmetric encryption was developed for this purpose. To help.
The essence of asymmetric encryption is based on two keys:
- Public key encryption, meaning that any recipient can see and access the data.
- Private key encryption: only authenticated recipients can access the data.
Very importantly, asymmetric encryption is based on these two keys. One encrypts and the other decrypts. The result? A high level of security.
A public key is a cryptographic key that can be used by any person to encrypt a particular message in such a way that it can only be decrypted by the recipient with his or her private key. The private key, also known as the secret key, is shared with the originator of the key.
So if we want to send a message using asymmetric cryptography, we can take the recipient’s public key from the public directory and use it to encrypt the message before we send it. The recipient will read the message as he decrypts it with the corresponding private key.
If, on the other hand, the sender of the message encrypts it with the private key, the message can be decrypted with the sender’s public key. The entire encryption and decryption process runs automatically. Users do not have to physically lock or unlock the message.
Many protocols are based on asymmetric cryptography. These include the TLS (Transport Layer Security) or SSl (Secure Sockets Layer) protocols that enable HTTPS.
The procedure of such encryption is also used in programs that need to establish a secure connection via an insecure (otherwise: unsecured) network, such as web browsers. Asymmetric cryptography is also used to validate digital signatures.
As already mentioned, the increased security is an advantage of asymmetric cryptography. It is the most secure and best- known encryption method. And why? Because users do not have to reveal their keys, let alone share them. This reduces the chances of cybercriminals intercepting a user’s private key during a transaction.
How does asymmetric cryptography work?
Quite simple! 🙂 Its entire mode of operation is based on the two keys mentioned. In asymmetric encryption, a mathematically related key pair is used for encryption and decryption. We talk about a private key and a public key. When we use the public key to encrypt, we decrypt the message with the private key. And of course, vice versa – if we use the private key to encrypt, only the corresponding public key can decrypt the message.
All asymmetric encryption is completed by the sender and the receiver. Everyone has their own key pair. How does this work in practice? The sender receives the public key from the recipient. Then he encrypts the message with the corresponding key. In this way, a so-called ciphertext is created. This is sent to the recipient, who decrypts the message with his private key. The transmitted message then has a readable, plain text.
The encryption function outlined above is one-way. This means that a sender cannot read another sender’s message even if he has the recipient’s public key.
Most commonly, asymmetric cryptography is used to authenticate data using digital signatures.
Interesting fact: A digital signature is a mathematical technique for confirming the authenticity and integrity of a message, software or digital document. It is the digital equivalent of a handwritten signature or seal.
We also use asymmetric cryptography in areas such as:
- Electronic mail. A public key can be used to encrypt a message and a private key to decrypt it.
- SSL/TLS. That is, encrypted connections between websites and browsers. Yes, asymmetric encryption is also used here.
- Cryptocurrencies. Users have their public keys, which everyone can see, and their private keys, which they keep secret. This ensures that only the rightful owners can spend the funds.
Advantages of asymmetric cryptography
First and foremost is security. It is increased because the private keys do not have to be disclosed.
Easy verification of the sender thanks to digital signatures. In addition, asymmetric cryptography enables non-repudiation, i.e. the sender cannot deny having sent the message in question.
Disadvantages of asymmetric cryptography
The method itself is slower than symmetric cryptography. Therefore, it is not used for decrypting mass messages.
The worst thing is that a person who loses his private key will not be able to decrypt the message. Speaking of keys, it is worth noting that public keys are not authenticated. So no one can assure us that the public key belongs to that particular person.
Some examples of asymmetric cryptography
- The most commonly used asymmetric algorithm is the RSA algorithm. It is embedded directly in SSl/TSL. The RSA algorithm derives its security from the difficulties involved in factoring large integers. These in turn are the product of two large prime numbers. RSA keys are usually 1024 or 2048 bits long.
- Elliptic Curve Cryptography (ECC). An alternative to RSA. This is a public key encryption technique based on elliptic curve theory. It can create faster, smaller or more efficient keys thanks to the properties of the elliptic curve. To crack the ECC algorithm, a cybercriminal must break the logarithm of the elliptic curve. This is definitely more difficult than factorization.
In asymmetric encryption, we need two types of keys – public and private – to decrypt the data sent to us. This increases the security of the messages being transmitted.
The idea of asymmetric encryption itself is not new. The concept was defined decades ago. In 1977, two researchers from Stanford University published a paper that dealt with this encryption technique. Over time, their idea spread and the result was this data protection solution.