Symmetric vs. Asymmetric Encryption: What’s the Difference?
Scammers are increasingly developing sophisticated ways to intercept data. But one foolproof method of protecting data from unauthorized access is encryption. This can be symmetric encryption, asymmetric encryption, or hash functions. In this article, learn what encryption is and understand the difference when comparing symmetric vs. asymmetric encryption.
What is encryption?
Encryption is a key aspect of cryptography. As we already know, cryptography is a method of encrypting and decrypting data. It involves converting plaintext, readable data, into ciphertext, ciphered data, and vice versa.
Encryption is a way of locking up information using cryptography. It’s a process of taking a message and scrambling its content so that only someone who has the appropriate key can decrypt it.
Put more technically, it’s a procedure of changing original text into an unreadable format known as ciphertext. The message will appear gibberish to anyone who doesn’t have a decipher key to open it.
The sender must run the messages through an encryption algorithm to get a ciphertext. This algorithm uses a mathematical procedure and a key to process unrecognizable text, which is a collection of letters and symbols.
Encryption helps secure the information we send, receive, and store over the device. Data exists as logs stored on your PC, text messages saved on your cellphone, or credit card details sent by your bank.
For example, the algorithm can convert your text from "HELLO WORLD" to “3ad77bb40d7a3660a89ecaf32466ef97”. You can only decrypt the message if you have the right key; thus, this protects it from unauthorized recipients.
There are two different forms of encryption: symmetric and asymmetric algorithms.
What is symmetric encryption?
Symmetric encryption is a type of encryption in which the same key is responsible for both encryption and decryption. In this type of encryption, both parties have the same key to open or lock data. This means the sender and receiver use the same secret key to encrypt and decrypt messages.
The two communicating parties must share the key and keep it confidential because anyone who possesses it can decrypt the ciphertext. The key encrypts plaintext into ciphertext and decrypts ciphertext back into plaintext.
Security depends on keeping it private. If someone compromises the key, attackers can hijack the data.
While the digital age has provided cyber criminals with new avenues to exploit priceless data, the main goal of symmetric encryption is to secure it as much as possible. Professionals apply it daily to protect data in various industries, such as defense, aerospace, banking, and healthcare.
How does symmetric encryption work?
Symmetric encryption involves the following steps:
- Key generation. The process generates a secret key as a string of bits the encryption algorithm uses. The strength of the encryption depends on the length and complexity of the key. Longer keys provide more robust encryption but may require more processing power.
- Encryption. The plaintext message (the original readable data) processes via the secret key. The algorithm transforms the plaintext into ciphertext, which is unreadable without the key.
- Transmission. The ciphertext then transmits over a communication channel, such as the Internet or a private network. Even if third parties intercept it, nobody without the secret key can read it.
- Decryption. Upon receiving the encrypted data, the receiver uses the same secret key to decrypt it. The decryption algorithm reverses the encryption process, converting the ciphertext into original data.
The main objective is data integrity, which is maintained as long as both sides manage the key carefully. This involves sharing the key with the right people and revoking access when necessary.
Features of symmetric encryption
Also known as secret-key encryption, symmetric encryption has several notable features, including using a single key for both encryption and decryption and its efficiency for encrypting large amounts of data. Symmetric encryption is faster because it uses simpler algorithms, and security depends upon the secrecy of the key. The encryption can, however, break if the key falls into the wrong hands.
Ultimately, symmetric encryption is easier to implement than other encryption methods.
Examples of symmetric encryption algorithms
The common ciphers in symmetric encryption are:
- AES (Advanced Encryption Standard), which supports key sizes of 128, 192, and 256 bits, making it highly versatile. The algorithm is deployed in various applications, including securing Internet communications and protecting sensitive data.
- DES (Data Encryption Standard), which was once a standard for encryption but has been largely replaced by AES due to its shorter key length of 56 bits. This type encrypts data in 64-bit blocks.
- 3DES (Triple DES), sometimes called Triple Data Encryption Algorithm, applies the DES algorithm three times to each data block to enhance security. It uses three 56-bit keys for a total of 168-bit strength. NIST deprecated its use in new applications in 2017, with full deprecation by 2023.
- Blowfish is known for its speed and flexibility. The method has a variable key length ranging from 32 to 448 bits, making it adaptable to different security needs.
- RC4 has been around for a long time. It encrypts data one byte at a time, so it is fast. However, RC4 is no longer recommended for secure applications due to vulnerabilities. RC4 was once widely used in protocols like SSL/TLS.
What is asymmetric encryption?
Asymmetric encryption, also known as public-key cryptography, is a type of encryption in which a pair of mathematically related keys—a public key and a private key—encrypt and decrypt data.
As with asymmetric encryption, the public key is shared openly among users to allow them to encrypt data. The private key is used for decryption and is not exchanged.
This dual-key system adds an extra layer of security compared to symmetric encryption. The two parties can exchange information without needing a shared secret key.
While asymmetric encryption is more secure, it is also slower. This is because the encryption and decryption processes involve complex mathematical operations.
In practice, when a message is encrypted with a public key, it can only be decrypted by the corresponding private key. Conversely, someone can decrypt a message encrypted with a private key with the corresponding public key.
How does asymmetric encryption work?
Asymmetric encryption uses two different keys: a public key and a private key. Here is a step-by-step guide to how asymmetric encryption works.
- Key pair generation. A pair of keys is generated: a public key and a private key. The public key is shared openly, while the private key is kept secret.
- Encryption. The sender uses the recipient's public key to encrypt the plaintext message. This ensures that only the recipient, who possesses the corresponding private key, can decrypt the message. The process transforms the plaintext into ciphertext.
- Transmission. The encrypted message is then transmitted to the recipient using a secure communication channel like HTTPS.
- Decryption. After receiving the encrypted message, the recipient uses their private key to decrypt it. The decryption algorithm produces the original plaintext message, making it readable for the recipient.
Asymmetric encryption's added security benefits make it essential for communication channels such as secure online banking, email, and e-commerce.
Features of asymmetric encryption
Asymmetric encryption is slower than symmetric encryption due to complex mathematical operations. However, it offers a safe communication method without requiring a secure channel. Asymmetric encryption notably uses two keys. It also works for a small amount of data compared to symmetric encryption.
Asymmetric encryption provides all three aspects of security: confidentiality, integrity, and accessibility. It also supports digital signatures, which verify the authenticity of a message or document. The keys used in asymmetric encryption remain undistributed and, therefore, have greater security.
Examples of asymmetric encryption algorithms
There are three popular mathematical permutations to encrypt a plaintext message today.
- RSA (Rivest-Shamir-Adleman) serves as one of the dominant asymmetric encryption algorithms often used in e-commerce protocols. It supports key lengths of 1024, 2048, and 4096 bits.
- ECC (Elliptic Curve Cryptography) is a method that works well to secure mobile devices, TLS certificates, and cryptocurrency. It capitalizes on the same level of security as RSA but with shorter key lengths.
- Diffie–Hellman (DH) key exchange, developed by Whitfield Diffie and Martin Hellman in 1976, may have inspired RSA. It enables two parties to establish a shared secret over an insecure communication channel.
Symmetric vs. asymmetric encryption
The main difference between symmetric and asymmetric encryption is the number of keys used and their distribution. However, there are several distinctions between the two. Assess the chart below for a full understanding of the differences when comparing asymmetric encryption vs. symmetric encryption.
| Feature | Symmetric encryption | Asymmetric encryption |
| Number of keys | Uses a single shared key for both encryption and decryption | Uses two different keys: a public key for encryption and a private key for decryption |
| Key management | Requires a secure channel to share the key | Public key can be openly shared |
| Performance and speed | Generally fast encryption process because it uses a single key | The encryption process in asymmetric encryption is slower due to the creation of two related keys instead of one |
| Size | The size of the ciphertext could be the same as or shorter than the plaintext (usually 128 or 256 bits) | The ciphertext size could be the same as or longer than the plaintext (sometimes 2048 bits or longer) |
| Purpose | Efficient, so it’s mainly for encrypting large amounts of data | Helps in transactions and establishment of secure connection channels before data transfer |
| Security | Less secure since it relies on a single key | More secure as it uses a pair of keys for encryption and decryption |
| Usage | Commonly used for encrypting data stored locally | Suitable for secure communication over a network |
| Existence | An older technique with historical roots | A newer technique developed in the late 20th century |
| Algorithms | Common algorithms include 3DES, AES, DES, and RC4 | Common algorithms include RSA, DSA, Diffie-Hellman, ECC, ElGamal, and ECDSA |
Applications of symmetric vs. asymmetric encryption
While both symmetric encryption and asymmetric encryption help secure data transfers and information exchange, they have slightly different applications. Symmetric encryption tends to work better in situations that rely on speed. Asymmetric encryption, on the other hand, prioritizes security at the cost of a slower exchange.
Use cases of symmetric encryption
Symmetric cryptography works better for situations that prioritize speed over enhanced security, though it still provides a high level of protection. Everyday use cases include:
- Banking. It protects transaction data in financial systems. It encrypts credit card information or other personally identifiable information (PII) required for transactions.
- Data storage. Symmetric encryption can encrypt files and databases to protect sensitive information.
- Secure messaging apps. It secures data transmitted over networks, such as emails and instant messages.
Use cases of asymmetric encryption
Asymmetric cryptography is best for situations that require prioritizing security and identity verification. Users often utilize it for:
- Digital signatures. Asymmetric cryptography confirms the identity of someone signing a document.
- Blockchain. Using asymmetric encryption to authorize transactions for cryptocurrency ensures only the rightful owner can initiate a transaction.
- Public Key Infrastructure (PKI). PKI involves governing encryption keys through the issuance of digital certificate.
Both symmetric and asymmetric encryption are useful for securing web traffic. A good scenario is SSL/TLS. Even most virtual private networks leverage the benefits of both methods in their operations. Symmetric encryption occurs via IPsec-supported AES, while the Diffie-Helman algorithm carries out asymmetric encryption.
Frequently asked questions
Symmetric vs. asymmetric encryption: which one is better?
It depends on the particular use case. If speed is the issue, you’ll want to use symmetric encryption. But if security is the concern, asymmetric encryption wins.
Does HTTPS use symmetric or asymmetric encryption?
HTTPS utilizes both methods to exchange keys securely and encrypt data. “S” in HTTPS stands for secure. The "Secure" aspect comes from using SSL/TLS over a computer network.
What is the biggest drawback of an asymmetric key?
The obvious disadvantage is that encryption and decryption in public-key encryption take more time because two different keys are used.
