Diagram: In this blog post, we discuss the difference between symmetric encryption (a single-key encryption technique) and asymmetric encryption (also known as public-key cryptography), which uses private and public key pairs to encrypt key.
Either transfer the key or not transfer the key. That's the problem.
There are two main forms of data encryption currently in use: symmetric encryption and asymmetric encryption. Symmetric and asymmetric encryption processes are happening every day when you use your web browser, answer emails, submit website forms, and other activities, sometimes without your knowing it. You may also be familiar with symmetric and asymmetric encryption because of your experience with OpenSSL, key management services, or you may have sent encrypted email or encrypted Microsoft Word or Adobe PDF files with a password before.
It is important to understand the difference between symmetric and asymmetric encryption and how these processes work in the transmission of everyday secure communications. When you see these terms, you'll understand what they mean, and you'll also learn how they work, their various iterations, understand their functionality, and know which is preferable in protecting and authenticating sensitive information at the source .
In this blog post, we will discuss the difference between symmetric and asymmetric encryption. Finally, we'll summarize these differences and discuss related encryption options for protecting sensitive data.
What is symmetric encryption?
Symmetric encryption is a widely used data encryption technique in which data is encrypted and decrypted using a single secret key.
Specifically, the key is used to encrypt the plaintext—the unencrypted or decrypted state of the data—and to decrypt the ciphertext—the encrypted or undecrypted state of the data.
Symmetric encryption is one of the most widely used encryption techniques and one of the oldest, dating back to the days of the Roman Empire. Caesar's cipher, named after Julius Caesar who used it to encrypt his military communications, is a famous historical example of symmetric encryption.
The goal of symmetric encryption is to protect sensitive, secret, or confidential information. It is used every day in many major industries, including defense, aerospace, banking, healthcare, and others, where protecting the sensitive data of an individual, business, or organization is critical.
How does symmetric encryption work?
Symmetric encryption works by using a stream cipher or block cipher to encrypt and decrypt data. Stream ciphers convert plaintext to ciphertext one at a time, and block ciphers convert entire units or blocks of plaintext using a predetermined key length (such as 128, 192, or 256 bits).
The sender and receiver who transmit data to each other using symmetric encryption must know the key to encrypt, in the case of the sender, the data they intend to share with the recipient, and in the case of the recipient, to decrypt and read the encrypted data of the sender and They are shared, and any necessary responses are encrypted.
Here is a simplified example of symmetric encryption: If the sender, Claire, wants to send a confidential document to the recipient, Jacqueline, Claire will encrypt the file with the key and send it to Jacqueline who cannot read its contents until she enters the The same key used to encrypt the file. Conversely, if Jacqueline makes changes to the document and wants to share it with Claire, she uses the same key to re-encrypt the file and sends it back to Claire, who uses the same key to decrypt the file and access its contents, and the process will repeatedly.
Note that this is just an example to simplify how symmetric encryption works. Symmetric encryption can be performed manually or automatically.
However, symmetric encryption is not limited to sharing data between one sender and one receiver. Anyone can access the symmetrically encrypted information - Claire, Jacqueline, their colleague Frank, their boss Jennifer and others. – who knows the key. This is why hiding the shared secret from unauthorized parties is critical to the success of symmetric encryption and the integrity of symmetric encrypted data.
What are some examples of symmetric encryption?
Popular examples of symmetric encryption include:
Data Encryption Standard (DES)
Triple Data Encryption Standard (Triple DES)
Advanced Encryption Standard (AES)
International Data Encryption Algorithm (IDEA)
TLS/SSL protocols
AES encryption uses block ciphers of 128, 192, or 256 bits To encrypt and decrypt data, it is one of the most famous and effective symmetric encryption techniques in use today. It takes billions of years to crack, which is why it is used to protect sensitive, secret, or classified information in government, healthcare, banking, and other industries. It is more secure than DES, Triple DES, and IDEA.
DES encryption is now recognized by the National Institute of Standards and Technology (NIST) as a legacy symmetric encryption algorithm because it has long been ineffective at protecting sensitive information from brute-force attacks. In fact, NIST has withdrawn the standard entirely, and its more secure big brother, Triple DES encryption, is facing the same fate. Although still in use today, Triple DES encryption will be withdrawn and banned by NIST in 2023 due to growing security concerns.
IDEA encryption was developed in the 1990s as a replacement for DES, but AES was ultimately considered more secure. IDEA is now an open and free block cipher algorithm, so anyone can use it, but it is generally considered outdated and ineffective for protecting sensitive and top secret information. AES encryption is the gold standard for both purposes.
Transport Layer Security (TLS) and its predecessor Secure Sockets Layer (SSL) use symmetric encryption. Basically, when a client accesses a server, a unique symmetric key is generated, called a session key. These session keys are used to encrypt and decrypt data shared between the client and server in a particular client-server session at a particular point in time. A new client-server session will generate a new, unique session key.
TLS/SSL uses not only symmetric encryption, but also symmetric and asymmetric encryption to ensure the security of client-server sessions and the information exchanged within them.
What are the advantages of symmetric encryption?
Symmetric encryption is used today because it can encrypt and decrypt large amounts of data quickly and is easy to implement. It's easy to use, and its iteration of AES is one of the most secure forms of data encryption available.
Now, symmetric encryption has several advantages over asymmetric encryption, but we will discuss asymmetric encryption later in this blog post.
Some advantages of symmetric encryption include:
Security: Symmetric encryption algorithms like AES take billions of years to crack using brute force attacks.
Speed: Compared to asymmetric encryption, symmetric encryption has a shorter key length and is relatively simple, so it is much faster to execute.
Industry Adoption and Acceptance: Symmetric encryption algorithms like AES have enjoyed decades of industry adoption and acceptance due to their security and speed advantages as the gold standard for data encryption.
What are the disadvantages of symmetric encryption?
By far the biggest disadvantage of symmetric encryption is that it uses a single secret key to encrypt and decrypt information.
Why?
Well, if this key is stored in an insecure location on the computer, hackers can use software-based attacks to gain access to it, allowing them to decrypt encrypted data, defeating the whole purpose of symmetric encryption.
Additionally, if one party or entity encrypts at one location and another party or entity decrypts within a second, a transmission key is required, which can be easily intercepted if the transmission channel is compromised.
That's why keeping encryption keys safe at rest and in transit is critical. Otherwise, you're just asking a barrage of independent and state-sponsored cyber attackers to gain access to your mission-critical, security-critical, or legally protected data.
The only other downside to using symmetric encryption is its security efficiency compared to asymmetric encryption, which is generally considered more secure than symmetric encryption, but is also slower to perform.
But is asymmetric encryption more secure than symmetric encryption? Let's find out.
What is asymmetric encryption?
Unlike symmetric encryption, which uses the same key to encrypt and decrypt sensitive information, asymmetric encryption, also known as public-key cryptography or public-key cryptography, uses a mathematically linked public and private key pair to encrypt and decrypt the sender and recipient Sensitive data about people.
As with symmetric encryption, plaintext is still converted to ciphertext and vice versa during encryption and decryption, respectively. The main difference is that two unique key pairs are used to asymmetrically encrypt data.
How does asymmetric encryption work?
Here's a simplified example of asymmetric encryption: If the sender, Claire, and the receiver, Jacqueline, want to keep sending each other confidential files, Claire and Jacqueline will provide each other with their unique public keys. Claire will then encrypt the file with Jacqueline's public key, since it is only for Jacqueline's use, and send the file to Jacqueline. After receiving the file, Jacqueline would use her private key -- the keyword "private," meaning no one else but Jacqueline knew about it -- to decrypt the file and access its contents. Not even Claire can decrypt the file except Jacqueline, because no one but Jacqueline knows Jacqueline's private key. The same process applies when Jacqueline wants to send the file back to Claire. Jacqueline associates it with Claire's public key,
Note that this is a simplification of asymmetric encryption. Like symmetric encryption, asymmetric encryption can be performed manually or automatically.
Now, do you see that asymmetric encryption is more secure than symmetric encryption? While this is an interesting question, it's not the right one, actually, because whether symmetric or asymmetric encryption is technically more secure depends largely on the key size and storing or transmitting the encryption key media security.
One reason asymmetric encryption is often considered more secure than symmetric encryption is that, unlike its counterpart, asymmetric encryption does not require the same encryption and decryption keys to be exchanged between two or more parties. Yes, public keys are exchanged, but users sharing data in an asymmetric cryptosystem have unique public and private key pairs, and their public keys, since they are used only for encryption, do not constitute a Risk of unauthorized decryption by hackers, because hackers assume the private key is kept secret, do not know the user's private key, and therefore cannot decrypt encrypted data.
Unlike symmetric encryption, asymmetric encryption also allows digital signature authentication. Basically, this involves using private keys to digitally sign messages or files, and their corresponding public keys are used to confirm that those messages are from the correct, verified sender.
What are some examples of asymmetric encryption?
Examples of asymmetric encryption include:
Rivest Shamir Adleman (RSA)
数字签名标准 (DSS)，其中包含数字签名算法 (DSA)
椭圆曲线密码学 (ECC)
Diffie-Hellman 交换法
TLS/SSL 协议
Published in 1977, RSA is one of the oldest examples of asymmetric encryption. RSA encryption, developed by Ron Rivest, Adi Shamir, and Leonard Adleman, generates a public key by multiplying two large random prime numbers together, and uses those same prime numbers to generate a private key. From there it's standard asymmetric encryption: information is encrypted with the public key and decrypted with the private key.
DSS combined with Digital Signature Algorithm (DSA) is a perfect example of asymmetric digital signature authentication. The sender's private key is used to digitally sign the message or file, and the recipient uses the sender's corresponding public key to confirm that the signature came from the correct sender and not from a suspicious or unauthorized source.
ECC is an alternative to RSA that uses smaller key sizes and mathematical elliptic curves to perform asymmetric encryption. It is often used to digitally sign cryptocurrency transactions; in fact, the popular cryptocurrency Bitcoin uses ECC — the Elliptic Curve Digital Signature Algorithm (ECDSA) to be exact — to digitally sign transactions and ensure that funds are sent only by authorized users. ECC is much faster than RSA in terms of key and signature generation, and is considered by many to be the future of asymmetric encryption, primarily for web traffic and encryption, but for other applications as well.
One of the greatest breakthroughs in cryptography, Diffie-Hellman is a key exchange method that two parties who have never met in person can use to exchange public and private key pairs over a public, insecure communication channel. Before Diffie-Hellman, two parties seeking to encrypt communications between each other had to physically pre-exchange encryption keys so that they could decrypt each other's encrypted messages. Diffie-Hellman does this so that these keys can be securely exchanged over public communication channels where third parties typically extract sensitive information and encryption keys.
TLS/SSL uses asymmetric encryption to establish a secure client-server session, while the client and server are generating symmetric encryption keys. This is called the TLS handshake. After the TLS handshake is complete, the client-server session key is used to encrypt the information exchanged in that session.
What are the advantages of asymmetric encryption?
The advantages of using asymmetric encryption include:
1. No need for key distribution:
Securing key distribution channels has always been a headache in cryptography. Asymmetric encryption eliminates key distribution entirely. The required public keys are exchanged via a public key server, at which point the disclosure of the public keys does not compromise the security of the encrypted message, as they cannot be used to derive the private key.
2. No need to exchange private keys:
With asymmetric encryption, private keys should be kept in a secure location and thus remain private to the entity using them. Basically, the keys needed to decrypt sensitive information are never and should never be exchanged over potentially compromised communication channels, which is a major advantage to the security and integrity of encrypted messages.
3. Digital signature/message authentication:
With asymmetric encryption, senders can use their private key to digitally sign a message or file and verify that the message or file is from them and not an untrusted third party.
There seems to be no problem with asymmetric encryption. I mean, why would you choose symmetric encryption if asymmetric encryption is so secure?
One word: speed.
What are the disadvantages of asymmetric encryption?
The main disadvantage of asymmetric encryption is that it is slower than symmetric encryption due to its longer key length, not to mention that asymmetric encryption tends to be much more computationally complex than symmetric encryption.
Why? Because in theory, the public key could be used to crack the private key - again, they are mathematically related - but the very long key lengths used by asymmetric encryption make this nearly impossible, at least for now.
So, in short, symmetric encryption is faster than asymmetric encryption. Asymmetric encryption sacrifices speed for security, and symmetric encryption sacrifices security for speed.
Now, that's not to say that symmetric encryption is insecure. However, the foundation of asymmetric encryption removes several information security risks that still exist in poorly managed symmetric encryption cryptosystems.
Conclusion: Summary of Key Differences
The key differences between symmetric and asymmetric encryption are speed and security preference. In general, symmetric encryption is faster and simpler, but is generally considered less secure than asymmetric encryption. But as we've discussed, encryption really comes down to two things: key size and the security of the medium on which the encryption key is stored.
Symmetric encryption performs much faster because it has a shorter key length. Asymmetric encryption tends to bog down the network due to its long key length and complex algorithm. These are trade-offs worth considering when deciding which type of encryption to employ.
At Trenton Systems, we provide data encryption solutions in the form of AES, Opal and FIPS-140-2 compliant self-encrypting drives (SEDs) in high-performance servers and workstations.
Pair it with our technology partner FUTURA Cyber's Cryptographic Management Platform (CMP), and you have a secure, well-managed computer that is resistant to common attacks on sensitive data.
For more information on how we use data encryption to ensure the integrity of your data, please contact us today.