Nowadays, the way we communicate and interact with each other online has taken modern communication to the point where it looks like magic. But reaping the fruits of technology comes at a price – abandoning our privacy.
With the development of the internet, actions such as hacking have become common, and their effects are often devastating.
Encryption has been around for thousands of years, but now we adapted it to our technological development. And in industries such as cryptocurrency, it plays a crucial role in supporting safety and anonymity.
There are two primary encryption techniques – symmetric and asymmetric.
But before we start discussing them, let’s define some of the terms we will encounter and find out how cryptography really works.
Cryptography terms you should know
- Encryption. The process of transforming simple text into unintelligible text.
- Decryption. The process of transforming unintelligible text into normal text.
- Key. A password or a code used to encrypt and decrypt information.
- Plaintext. The standard message, without any form of encryption.
- Ciphertext. The encrypted message.
What is Cryptography?
Back in the day, cryptography was mostly used in military or government operations. But with the recent technological evolution, it quickly found its place in most of life’s aspects.
Cryptography uses complex mathematical formulas to convert simple text into unintelligible in order to hide the message. Cryptography has two steps in its most basic formula: encryption and decryption.
Encryption uses a cipher to encrypt the plaintext and turn it into ciphertext. Decryption, on the other hand, applies the same cipher to turn the ciphertext back into plaintext.
Here’s an example of what a message encrypted using Caesar’s cipher would look like:
Sd nyocx’d bokvvi wkddob.
Let me know in the comments if you can figure out what it says.
And while at a glance, the text might look unreadable, the process is really simple once you know how the encryption method works. Also known as a shift cipher, Caesar’s cipher shifts each letter by a set number of spaces to the right or to the left of the alphabet.
So, if we choose to switch by seven spaces to the right, we’re left with the following:
- A = H
- B = I
- C = J
- D = K
- …
- W = D
- X = E
- Y = F
- Z = G
As you can see, Caesar’s cipher is pretty straightforward, which is why it’s one of the easiest to solve. All you have to do is figure out the number of spaces the alphabet was switched with.
What is Symmetric Encryption?
Symmetric encryption is the most basic form of encryption, with Caesar’s cipher serving as a perfect example. It involves the use of a shared secret key to both encrypt and decrypt data, ensuring its protection. This key, which can be a word, phrase, or a combination of characters, is known to both the sender and the recipient, allowing them to lock and unlock the information securely.
Symmetric encryption is usually used by banks, as it efficiently protects PII (Personal Identifying Information) without huge costs of resources. This helps lower the risk involved in dealing with payment transactions daily.
How Does Symmetric Encryption Work?
As we said above, symmetric encryption uses a single secret key to encrypt and decrypt information, making the process relatively simple. A message is encrypted using the secret key on computer A. It is then transferred to computer B, which decrypts it using the same key.
Since both the encryption and the decryption process use the same key, symmetric encryption is faster than its counterpart, which is why it is usually preferred for large files that need mass encryption – such as databases.
Still don’t get it? Visualize Hannah wants to send a confidential message to David using symmetric encryption. Here’s how it would work:
- Key Generation – Hannah and David agree on a shared secret key. Let’s say they both agree on the key “COINDOOKEY777”.
- Encryption – Hannah takes her plaintext message, such as “HELLO,” and applies an encryption algorithm (e.g., AES) along with the shared key “COINDOOKEY777.” The encryption algorithm transforms the plaintext into ciphertext, which is the encrypted form of the message.
- Ciphertext Transmission – Hannah sends the ciphertext to David through a secure channel or any communication medium.
- Decryption – David, who also possesses the shared key “COINDOOKEY777,” receives the ciphertext. He applies the same encryption algorithm and the shared key to decrypt the ciphertext. As a result, the ciphertext is transformed back into the original plaintext message, which in this case is “HELLO.”
Examples of Symmetric Encryption
Now that you understand more clearly how symmetric encryption works, you must know some examples of existing and commonly used symmetric encryption.
So, you need to know that modern symmetric encryption methods include AES (Advanced Encryption Standard), 3DES (Triple Data Encryption Standard), and Blowfish. They are not the only ones, but they are the most common.
The algorithm recommended by the US National Institute of Standards Technology is AES. Thus, the most popular ones are AES-128, AES-192, and AES-256.
Advantages of Symmetric Encryption
Efficiency
Symmetric encryption algorithms are computationally efficient, making them ideal for quickly encrypting and decrypting large volumes of data. This efficiency makes symmetric encryption suitable for real-time communication, file encryption, and data storage.
Simplicity
Symmetric encryption is relatively straightforward to implement and use. It involves a single key for both encryption and decryption, simplifying the process compared to asymmetric encryption, which requires managing key pairs.
Speed
Since symmetric encryption uses a single key, the encryption and decryption processes are faster than asymmetric encryption, which involves complex mathematical operations. This speed is beneficial for applications where time is critical, such as secure communication or high-speed data processing.
Data Integrity
In addition to confidentiality, symmetric encryption can also ensure data integrity. Encrypting the data with a shared key will render any unauthorized modification of the ciphertext undecipherable during decryption, thereby detecting potential tampering or unauthorized changes.
Compatibility
Symmetric encryption algorithms are widely supported and compatible across various platforms, devices, and programming languages. This compatibility facilitates seamless integration and interoperability between different systems and applications.
Resource Efficiency
Symmetric encryption requires fewer computational resources than asymmetric encryption, making it more suitable for resource-constrained environments such as mobile devices or embedded systems.
Secure Communication Channels
Symmetric encryption is often used to establish secure communication channels, such as Virtual Private Networks (VPNs) or Secure Socket Layer (SSL)/Transport Layer Security (TLS) protocols. It ensures that data transmitted between parties remain confidential and protected against eavesdropping or unauthorized access.
Disadvantages of Symmetric Encryption
Key Distribution (or Exchange), Management and Updates
One of the significant challenges in symmetric encryption is securely distributing the shared secret key to all authorized parties. If the key is compromised or falls into the wrong hands during distribution, it can lead to unauthorized access and decryption of sensitive data.
Symmetric encryption does not inherently provide a mechanism for secure key exchange between two parties who have never communicated. Establishing a secure channel for initial key exchange can be challenging, especially when parties are geographically dispersed or lack a pre-existing trust relationship.
Also, as the number of users and systems increases, managing and securely storing the shared secret keys becomes more complex. The larger the network, the greater the risk of key exposure or loss, requiring robust key management practices.
Moreover, changing or updating the shared secret key in symmetric encryption can be cumbersome. It requires re-establishing secure communication channels and re-encrypting all existing data with the new key, which can be time-consuming and resource-intensive.
Scalability
Symmetric encryption faces scalability issues when multiple parties must communicate securely in a network. Since each pair of users requires a unique shared secret key, the number of required keys grows exponentially as the number of users increases, making key management and distribution more difficult.
Limited Authentication
Symmetric encryption does not provide inherent authentication mechanisms. It only ensures the confidentiality of the message but does not verify the sender’s identity or protect against message tampering. Additional protocols or mechanisms must be implemented to address authentication and integrity concerns.
Lack of Forward Secrecy
In symmetric encryption, if the shared key is compromised, all past and future communications encrypted with that key become vulnerable. There is no forward secrecy feature, meaning that compromising the key compromises the confidentiality of all previously encrypted data.
Trust Assumptions
Symmetric encryption assumes that both parties share and trust the same key. If there is a breach of trust, such as a malicious insider or a compromised party, the security of the encrypted data can be compromised.
What is Asymmetric Encryption?
Also known as Public-Key Cryptography, asymmetric cryptography uses more than one key of two types – public and private. Each key performs a specific function in the encryption and decryption process.
And I’m sure this sounds familiar to those of you who own a crypto wallet.
As their names suggest, a public key is a key that is publicly available to anyone, while a private key is secret. Only the owner must know it.
How Does Asymmetric Encryption Work?
Instead of using a single key to decrypt and encrypt information, asymmetric encryption uses two of them. A message encrypted by a public key can only be decrypted by a private key. And naturally, a message encrypted by a private key can only be decrypted using a public key.
SIDENOTE. Asymmetric encryption systems frequently use more than only two keys. Some algorithms use five keys, which highly increases the security and the total number of possible solutions to decrypt a message.
Using two keys makes the encryption and decryption process very complex, improving the security it provides. This makes them a crucial ingredient in today’s cryptosystems by providing anonymity and validity.
For a better understanding, let’s transpose Hannah and David into an example of asymmetric encryption to find how asymmetric encryption works:
- Key Generation – David wants to enable secure communication with Hannah. David generates a key pair consisting of a public and private key. The private key is kept secret, while the public key is shared with Hannah.
- Encryption – Hannah wants to send a confidential message to David. She obtains David’s public key and uses it to encrypt the plaintext message. The encryption algorithm takes the public key and the message as input and generates the ciphertext.
- Transmission – Hannah sends the encrypted ciphertext to David through any communication channel, even an insecure one.
- Decryption – David, the only one in possession of the corresponding private key, uses it to decrypt the ciphertext received from Hannah. The decryption algorithm inputs the private key and the ciphertext and produces the original plaintext message. Now, Hannah uses David’s public key to encrypt the message, and only David, with his private key, can decrypt and read it. This ensures confidentiality, as even if an adversary intercepts the ciphertext, they cannot decrypt it without David’s private key.
Basically, asymmetric encryption forms the fundamental cornerstone of the cryptographic wallet framework that underpins the entire crypto space. It is the bedrock for secure communication, data integrity, and authentication, enabling users to exchange information safely without needing a pre-shared secret key.
Examples of Asymmetric Encryption
One of the first public-key encryption systems is RSA (Rivest-Shamir-Adleman), which was first presented in 1978. Today, some of the most widely used algorithms for asymmetric encryption are Diffie-Hellman and Digital Signature Algorithms.
The main difference between these algorithms is that some provide key distribution and anonymity, others provide digital signatures, and others offer both.
However, one problem still needs fixing – the proof of authenticity.
This is where digital certificates come in.
For asymmetric encryption to work, we need a way to validate the authenticity of the transmitted message.
One solution is through the usage of digital certificates. A digital certificate is a package of information identifying a user and a server. Think of it as your ID.
It contains your name (or your organization’s name), the name of the organization that issued the certificate, your e-mail address, your country of origin, and your public key.
When a person sends an encrypted message through a secure channel, his digital certificate is automatically included. This helps identify the two users/devices and establishes a secure communication channel.
Advantages of Asymmetric Encryption
Secure Key Exchange
Asymmetric encryption provides a secure method for exchanging encryption keys between parties who have never communicated. The sender can use the recipient’s public key to encrypt the key, ensuring that only the recipient with the corresponding private key can decrypt and access it. This feature eliminates the need for a pre-shared secret key, simplifying the key exchange process and enhancing security.
Confidentiality and Privacy
Asymmetric encryption enables confidential communication by encrypting messages with the recipient’s public key. Only the recipient possessing the corresponding private key can decrypt and read the message. This ensures that sensitive information remains private and protected from unauthorized access.
Authentication and Non-Repudiation
Asymmetric encryption facilitates digital signatures, allowing individuals to sign messages or documents with private keys. The recipient can verify the signature using the sender’s public key, ensuring the authenticity and integrity of the message. Also, digital signatures provide non-repudiation, as the sender cannot deny having signed the message, providing strong evidence of the message’s origin.
Scalability and Flexibility
Asymmetric encryption supports secure communication between multiple parties without requiring a separate key for each pair. This scalability makes it suitable for scenarios where secure communication is required between a large number of participants. Moreover, asymmetric encryption can be used in conjunction with symmetric encryption for a hybrid approach, leveraging the advantages of both encryption methods.
Trust and Public Key Infrastructure (PKI)
Asymmetric encryption forms the foundation of Public Key Infrastructure (PKI), which includes digital certificates issued by trusted Certificate Authorities (CAs). These certificates bind an individual’s identity to their public key, establishing trust and enabling secure communication across networks and systems.
Compatibility and Standards
Asymmetric encryption algorithms such as RSA and Elliptic Curve Cryptography (ECC) are widely adopted and supported by various cryptographic libraries and systems. This compatibility ensures interoperability across different platforms, devices, and applications, making it a reliable choice for secure communication.
Disadvantages of Asymmetric Encryption
Computational Complexity
Asymmetric encryption algorithms are computationally more intensive compared to symmetric encryption algorithms. The mathematical operations involved, such as modular exponentiation or elliptic curve calculations, require more computational resources. As a result, asymmetric encryption can be slower and less efficient, especially when encrypting or decrypting large amounts of data.
Key Length and Storage
Asymmetric encryption requires longer key lengths than symmetric encryption to achieve the same level of security. The larger key sizes result in longer encryption and decryption times and increase the storage requirements for keys. Managing and securely storing these longer keys can be challenging, especially in resource-constrained environments.
Performance Impact
The computational complexity of asymmetric encryption algorithms can impact system performance, particularly in scenarios where encryption and decryption operations are performed frequently or in real time. Applications that rely heavily on encryption, such as secure communications or high-volume transactions, may experience performance bottlenecks when using asymmetric encryption.
Key Distribution and Management
Asymmetric encryption relies on the secure distribution and management of public keys. Verifying the authenticity and integrity of received public keys can be a challenge, as attackers could potentially impersonate the intended recipient or modify the public key during transmission. Establishing a trusted Public Key Infrastructure (PKI) and implementing secure key distribution mechanisms are essential but can introduce additional complexity.
Limited Key Size for Some Algorithms
Specific asymmetric encryption algorithms have limitations on the key size due to their mathematical properties. For example, RSA encryption is typically limited to a specific key size to maintain acceptable performance. This limitation can impact the long-term security of the encryption method as computational power advances, making it easier to break shorter key lengths.
Forward Secrecy
Unlike symmetric encryption, asymmetric encryption does not provide forward secrecy. If a private key is compromised, all past communications encrypted with the corresponding public key become vulnerable to decryption. This lack of forward secrecy means that the compromise of a private key can retroactively expose previously encrypted data.
Reliance on Trusted Public Keys
Asymmetric encryption assumes the authenticity and integrity of public keys used for encryption and verification. If an attacker manipulates or substitutes the public key, they can decrypt intercepted messages or deceive the recipient. Verifying the trustworthiness of public keys becomes critical to ensure secure communication.
FAQ
What are the Differences Between Symmetric and Asymmetric Encryption?
The main issue with today’s encryption systems is the difficulty of exchanging the secret key over the internet. This is why most systems use a combination of both symmetric and asymmetric encryption.
Asymmetric encryption delivers the code needed to decipher symmetric encryption.
Essentially, asymmetric encryption serves as a set of rules on how to start decrypting the message. It explains how to unlock the cipher required to decrypt the initial data.
Therefore, trying to state that one encryption is better than the other is difficult. But here are the main differences between the two systems.
- Symmetric encryption uses a single key to encrypt and decrypt information, while asymmetric encryption uses more keys of two different types – public and private.
- While symmetric encryption is faster and ideal for encrypting large amounts of data, asymmetric encryption is usually used to transmit the code needed to decipher the symmetric encryption.
- Asymmetric encryption is a modern algorithm, while symmetric encryption has been around for approximately 2,000 years.
- Symmetric encryption is a relatively simple process, while asymmetric encryption is far more complex and thus harder (but not impossible) to break using pure computational power.
Which is More Secure – Symmetric or Asymmetric Encryption?
This is a difficult question to answer.
Most people believe that asymmetric encryption is more secure since it has both a public and a private key. But comparing the strength and resistance to attack of symmetric and asymmetric encryption isn’t that easy.
What is important here is the context.
Symmetric encryption is better used when sharing information between a smaller number of people. It is easier to use and understand, so the information is less likely to be misinterpreted.
Moreso, algorithms for symmetric encryption/decryption tend to work faster.
On the other hand, asymmetric encryption works better on large groups of people (such as the internet).
Most of today’s systems (such as SSL or TLS) use a combination of both symmetric and asymmetric encryption, as well as other algorithms.
Therefore, saying which of the two encryption methods strictly depends on the context.
What is the Biggest Drawback of Symmetric Key Cryptography?
The biggest drawback of symmetric key cryptography is the secure distribution of the secret key. Since both the sender and receiver need the same key for encryption and decryption, securely sharing the key becomes a significant challenge, especially when the communicating parties have not previously established a trusted channel.
Final Thoughts
Encryption is a complex topic, but it usually boils down to what you want to use it for.
This makes it hard to say that “asymmetric is better than symmetric” or vice-versa. While symmetric encryption might be the best fit for certain situations, asymmetric encryption might be the better choice in other cases.
And while it might seem easy to say that encryption is strictly the concern of developers, that’s simply wrong. All of us should have a basic idea of how internet security works. That will help us better defend against potential attacks and foster responsible behavior regarding online activity.
