Symmetric And Asymmetric Key Cryptography: A Detailed Guide In 2022

Introduction

Choosing encryption software to secure sensitive data may be difficult for someone who’s not a techie or is relatively new to cryptography, particularly between symmetric and asymmetric key cryptography. 

A well-rounded approach for securing digital transactions includes the use of both symmetric and asymmetric key cryptography. Each method of data security has its advantages when implemented in the right scenarios. Let us look at what symmetric and asymmetric keys are, the distinction between them, and which one to choose based on their advantages and disadvantages.

1. What is Symmetric and Asymmetric Key Cryptography?
2. Symmetric Key Cryptography
3. What is the Purpose of Symmetric Encryption?
4. Asymmetric Key Cryptography
5. What is the Purpose of Asymmetric Encryption?
6. What is the Difference Between Symmetric Key Cryptography And Asymmetric Key Cryptography?
7. What are the Advantages and Disadvantages of Symmetric and Asymmetric Key Cryptography?
8. Asymmetric Key Cryptography

DEFINITION OF ALGORITHMS AND CRYPTOGRAPHIC CONCEPTS

Algorithms

A procedure or formula for resolving a data snooping issue is what we mean by an algorithm. A set of mathematical procedures for encrypting data is an encryption algorithm. A key is needed to decipher the ciphertext and return the data to its original form using such an algorithm. This brings us to the long-established field of cryptography, which is concerned with ensuring the confidentiality and integrity of digital data and communications.

Cryptography

Cryptography is a method of storing and transmitting data in a specific form so that only those who are meant to see and process that data can do so. This is done using advanced mathematical concepts. Encryption is a fundamental concept in cryptography – It is the process of encoding a message in a way that an eavesdropper cannot decipher. Using this method dates back to the time of Caesar when he used Caesar’s cipher to encrypt his messages. Encryption and transmission of a user’s plain text via a communication channel ensure that an eavesdropper cannot access it. Decryption occurs at the receiver’s end, so the plain text is restored.

Cryptography Terminology

• Encryption: It is the process of coding or locking up the data/information using cryptography. The data that is locked is said to be encrypted.
• Decryption: It is the process of unlocking or decoding the encrypted data/information using cryptographic techniques.
• Key: A password or string of characters for encrypting and decrypting the data. Different types of keys are used in cryptography. It is only known to the sender and the receiver of the information. For example, symmetric-key cryptography makes use of secret keys for both encryption and decryption.

1. What is Symmetric and Asymmetric Key Cryptography?

Unauthorized access to all types of data is an ever-present risk in today’s cyber world. Financial and payment system data are the most vulnerable data, which may reveal consumers’ and clients’ personal identifying information (PII) or payment card records. 

Encryption is critical for securing personally identifiable information and mitigating the threats for companies that perform payment transactions every minute of the day. This makes cryptography crucial. There are mainly two types of cryptography: symmetric and asymmetric cryptography.

2. Symmetric Key Cryptography

Symmetric Key Cryptography, or Symmetric Encryption, uses a secret key for both encryption and decryption. This approach is the inverse of Asymmetric Encryption, which uses one key to encrypt and another to decrypt. Data is translated to a format that cannot be interpreted or inspected by someone who does not have the secret key used to encrypt it during this phase.

The strength of the random number generator used to generate the secret key determines the effectiveness of this method. Symmetric Key Cryptography, commonly used on the Internet today, comprises two kinds of algorithms: Block and Stream. The Advanced Encryption Standard (AES) and the Data Encryption Standard (DES) are two common encryption algorithms. This type of encryption is typically much faster than Asymmetric Encryption, but it allows the secret key to be held by both the sender and the data receiver.

Symmetric cryptography is based on a single shared key that all parties are aware of and can use to encrypt and decrypt data.

Secret-key, single-key, shared-key, one-key, and private-key encryption are other words for symmetric-key cryptography. The usage of the last and first words will lead to misunderstanding compared to the related language used in public-key cryptography.

Symmetric key encryption employs one of the following encryption techniques:

Stream ciphers: Encrypt a message’s digits or letters one at a time.

Block ciphers: Encrypt a group of bits as a single entity, inserting the plaintext to make it a block size multiple. 64-bit blocks are widely used. The NIST-approved Advanced Encryption Standard (AES) algorithm and the GCM block cipher mode of operation all use 128-bit blocks.

3. What is the Purpose of Symmetric Encryption?

Although symmetric encryption is an older type of encryption, it is simpler and more effective than asymmetric encryption, which strains networks due to data size performance problems and heavy CPU usage. 

Since symmetric encryption performs smoother and quicker than asymmetric encryption, it is commonly used for bulk encryption / encrypting massive volumes of data, such as database encryption. In a database, the secret key can be used only by the database to encrypt or decrypt data.

Here are a few instances of where symmetric cryptography is used:

• Payment applications, such as bank purchases, where personally identifiable information (PII) must be secured to avoid identity theft or fraudulent charges

• Validations are performed to ensure that the sender of a message is who he appears to be.

• Hashing or random number creation

4. Asymmetric Key Cryptography

Asymmetric cryptography, better known as public-key cryptography, encrypts and decrypts a message using a pair of similar keys. In asymmetric key cryptography, the private key is kept by one public key and one private key — to prevent unauthorized entry or usage. Anybody can use a public key to encrypt a document so that only the expected receiver can decrypt it with their private key. A private key or secret key is only known to the key’s generator.

When anyone tries to submit an encrypted message, they will use a shared directory to retrieve the recipient’s public key and use it to encrypt the message until submitting it. The message will then be decrypted by the receiver using their associated private key. 

However, when the sender encrypts the message using their private key, the message may only be decrypted using the sender’s public key, thus authenticating the sender. These encryption and decryption procedures are automatic; users don’t need to lock and unlock the message manually.

Numerous protocols, including the transport layer security (TLS) and safe sockets layer (SSL) protocols that allow HTTPS, depend on asymmetric cryptography. Encryption is often used in browsers that need to create a stable link over an unstable network, such as the Internet, or to verify a digital signature.

The key advantage of asymmetric cryptography is increased data security. Since users are never expected to disclose or exchange their private keys, the risks of cyber activity on a user’s private key during transmission are reduced.

5. What is the Purpose of Asymmetric Encryption?

Asymmetric encryption uses: Asymmetric cryptography is often used to check the authenticity of data using digital signatures. A digital signature is a cryptographic technique for verifying the validity and credibility of a message, software, or digital record. It’s the equivalent of an in-person signature or a sealed seal in digital form.

Digital signatures, which are based on asymmetric cryptography, may include proof of the origin, identification, and status of an electronic record, transaction, or post, as well as acknowledge the signer’s informed consent.

You can also use asymmetric encryption in applications where many users can encrypt and decode messages, such as:

• Encrypted email entails using a public key to encrypt a file and a private key to decode it.

• Asymmetric encryption is often used in the SSL/TSL cryptographic protocols, which provide encrypted connections between websites and browsers.

• Asymmetric encryption is used for Bitcoin and other cryptocurrencies when consumers provide public keys that everybody will use and private keys held hidden. Bitcoin employs a cryptographic algorithm to guarantee that only the funds belonging to rightful owners can be spent.

• Each unspent transaction output (UTXO) in the Bitcoin ledger is usually associated with a public key. So, suppose user A needs to give user B some money and has a UTXO associated with his public key. In that case, he uses his private key to sign a contract that spends the UTXO and makes a new UTXO associated with user B’s public key.

6. What is the Difference Between Symmetric Key Cryptography And Asymmetric Key Cryptography?

So, when it comes to the difference between symmetric and asymmetric encryption, which one is more secure? Asymmetric encryption is more stable than symmetric encryption, but it is slower. They’re both powerful in their own ways, and depending on the job at hand, one or both may be used individually or together.

The table below compares symmetric and asymmetric encryption in greater detail. Some of these variations are due to the different types of keys used, and others are due to the length of time it takes to compute the encryption methods.

Symmetric Key Cryptography	Asymmetric Key Cryptography
There is just one key (symmetric key) used, and it is the same key used to encrypt and decrypt the message.	For encryption and decryption, two different cryptographic keys (asymmetric keys), known as the public and private keys, are used.
Since it is a straightforward procedure, the encryption method can be completed easily.	It is a much more complex and time-consuming mechanism than symmetric key encryption.
Key lengths are usually 128 or 256 bits, depending on the security criteria.	The key length is even greater; for asymmetric encryption example, the recommended RSA key size is 2048 bits or higher.
It is also called secret-key cryptography or private key cryptography.	Asymmetric key is also called a conventional cryptography system or public-key cryptography.
Represented mathematically as:P=D(K,E(P))	Represented mathematically as:P=D(Kd,E(Ke,P))
It uses fewer resources than an asymmetric key cipher uses.	It consumes more resources than symmetric key cryptography.
It is used where massive amounts of data may be transmitted.	It is mainly used in smaller transactions to authenticate and create a stable contact channel before data transfer.
The secret key is shared. As a result, the likelihood of compromise is increased.	Since the private key is not shared, the overall process is more reliable than symmetric encryption.
Symmetric encryption is an old technique.	Asymmetric encryption is relatively new.
RC4, AES, DES, 3DES, and other algorithms are examples.	RSA, Diffie-Hellman, ECC, and other asymmetric encryption algorithms are examples.

7. What are the Advantages and Disadvantages of Symmetric and Asymmetric Key Cryptography?

Symmetric Key Cryptography

The versatility of the symmetric encryption method is its most significant advantage. However, the versatility of symmetric encryption algorithms is not without flaws — it suffers from a problem known as “key distribution.” 

Advantages

• A symmetric cryptosystem is more effective.

• Encrypted data can be transmitted over a network in Symmetric Cryptosystems even though it is certain that the data would be intercepted. Since no key is sent with the files, the chances of data decryption are zero.

• To confirm the receiver’s existence, a symmetric cryptosystem employs password authentication.

• A message can only be decrypted by a device that has a hidden key.

• Prevents widespread message protection breaches. For communicating with each party, a separate secret key is used. Only communications from a specific pair of sender and recipient are impacted when a key is corrupted. Communication with others is always safe.

• This type of encryption is simple to implement. All users need to do is specify and exchange the secret key until they can begin encrypting and decrypting messages.

• Encrypt and decrypt your files. There is no need to build separate keys if you use encryption for messages or data that you wish to access just once. For this, single-key encryption is ideal.

• Symmetric key encryption is much faster than asymmetric key encryption.

• Uses fewer computer resources. As opposed to public-key encryption, single-key encryption needs fewer computing resources.

Disadvantages

• Key transportation is a concern in symmetric cryptosystems. The secret key must be sent to the receiving device before the final message is sent. Electronic communication is unreliable, and no one can guarantee the communication networks will not be tapped. As a result, the only safe method of sharing keys will be to do it in person.

• It is not possible to have digital signatures that cannot be revoked.

• The message’s origin and validity cannot be assured. Messages cannot be proven to have originated from a specific person since both sender and recipient use the same key. If there is a disagreement, this may be a challenge.

• For communication between each different party, a new shared key must be created. This poses a challenge with handling and securing both of these keys.

8. Asymmetric Key Cryptography

Asymmetric encryption is an alternative mode of cryptography that helps overcome the major distribution issues that arise due to the symmetric encryption process. As with all the other aspects of the world, everything has a cost — and asymmetric encryption is no exception. In this scenario, the cost is reduced by speed and computing resources due to the use of longer keys in this encryption algorithm. As a result, asymmetric encryption is deemed slower but more reliable than symmetric encryption.

Advantages

• There is no need to exchange keys in asymmetric or public key cryptography, eliminating the key distribution issue.

• The main benefit of public-key cryptography is improved security: private keys are never exchanged or exposed to others.

• May provide digital signatures that can be revoked.

• Message verification is provided by public-key cryptography, which requires the use of digital signatures, which allows the receiver of a message to check that the message is actually from a specific sender.

• The usage of digital signatures in public-key cryptography helps the recipient to determine whether or not the message was altered during transit. A digitally signed message cannot be altered without rendering the signature null.

• Signing a message digitally is analogous to physically signing a document. Since it is an acknowledgement of the message, the sender cannot reject it.

Disadvantages

• One drawback of using public-key cryptography for encryption is the lack of speed. Popular secret-key encryption systems are substantially quicker than any commonly accessible public-key encryption technique.

• Authentication of public keys is recommended/required. No one can be certain that a public key corresponds to the individual it identifies, so everybody must verify that their public keys are theirs.

• It consumes more computer resources. It necessitates much more computing resources than single-key encryption.

• A widespread security breach is likely if an intruder obtains a person’s private key and reads his or her entire message.

• The loss of a private key can be irreversible. When a private key is lost, all incoming messages cannot be decrypted.

While asymmetric cryptography is more advanced than symmetric cryptography, both are still in use today — and are often used in tandem. This is because each solution has its advantages and disadvantages. There are two significant trade-offs between symmetric and asymmetric cryptography: speed and security. 

Since it does not include the exchange of keys, asymmetric encryption is thought to be more reliable. A user’s private key is never revealed or shared. Symmetric encryption takes longer than symmetric encryption and is generally a slower process. However, this is not a significant disadvantage, and it is commonly used to encrypt data where confidentiality is the primary concern.

Conclusion

Keeping large-scale symmetric encryption systems operational is a challenge. This is particularly true where the corporate or IT infrastructure is decentralized/geographically dispersed, and we want to achieve banking-grade protection and audibility. It is advised that specific software be used to ensure the appropriate life-cycle for and key generated to do this correctly. 

Apart from SSL, a variation of each of these strategies is seen in various other situations. End-to-end encryption is utilized for messaging apps like Signal and WhatsApp, where asymmetric encryption is used to initialize the secure communication channel, and symmetric encryption is used for the rest of the conversation. When it comes to encryption, the more recent schemes are not always the perfect fit. 

Indeed, as cryptography evolves, modern algorithms are being built to keep up with eavesdroppers and secure knowledge to improve secrecy. In the coming years, hackers would undoubtedly make it difficult for experts but you can expect more from the cryptographic world!

So, have you made up your mind to make a career in Cyber Security? Visit our Master Certificate in Cyber Security (Red Team) for further help. It is the first program in offensive technologies in India and allows learners to practice in a real-time simulated ecosystem, that will give them an edge in this competitive world.

Also Read

• What is TLS? A Comprehensive Guide in 4 Points