Encryption Algorithms Explained And How To Pick One

We are going to discuss “Encryption Algorithms“. Often accused of hiding terrorist activities by political entities, encryption is just one of those cybersecurity topics in the headlines. Anyone with a decent grasp of the various kinds of encryption may feel like a sort of injustice has been done to this remarkable technology that is at the heart of online security and privacy.

Encryption is a procedure of converting information into a format that only the authorized parties can access the data.  Cryptographic keys, along with encryption algorithms, are what make the encryption process potential.

And, depending on the way these keys are applied, there are primarily two kinds of encryption methods which are mostly used: “symmetric encryption” and “asymmetric encryption” Both these approaches use a different mathematical algorithm to scramble the information. This list of standard encryption algorithms includes ECC, 3DES, RSA, AES, etc.

In this guide, you’ll learn about asymmetric & symmetric and their encryption and encryption algorithms used to encrypt information.

Let’s hash it out.

First Type of Encryption: Symmetric Encryption

The encryption method, as the name suggests, uses a single key to decrypt and encrypt data. Using a single key for both operations makes it a simple process, and hence it is known as “symmetric.”

Here’s how symmetric encryption works. Let us understand the symmetric encryption procedure with a simple example:

There are two friends named Alice and Bob who are living in New York. For some reason, Alice has to move from the city. The only way they can converse with each other is through postal mail.   But there’s one problem, Alice and Bob are terrified that somebody could read their messages.  To protect their letters from someone’s eyes, they choose to write their message in such a way that a letter replaces each letter of the message seven positions down the alphabet. So, rather than writing “Apple,” they’d write”hwwsl” (A -> H, P -> W, L -> S, E -> L). To turn back the data, they’d have to replace the letter seven places up the alphabet order.

This may sound simple to you and on the surface it is. This technique was used centuries ago by Julius Caesar, the Roman emperor, and military general. Known as “Caesar’s cipher,” this approach works on the technique of alphabet substitution.

The encryption methods of today are not as straightforward as that. The widely used encryption algorithms are so complicated that they can not be cracked by computing power. And that is the reason we can relax and send our credit card information without any concerns.

What Makes Symmetric Encryption an Excellent Technique

Symmetric encryption’s most outstanding feature is the simplicity of its process. This simplicity of the sort of encryption lies in using one key for both encryption and decryption. Because of this, symmetric encryption algorithms:

  •  Are significantly faster than their asymmetric encryption criteria
  •  Require less computational power
  •  Do not dampen net speed.

This means that when there is a chunk of information to be encrypted symmetric encryption turns out to be an excellent option.

3 Kinds of Symmetric Encryption Algorithms

Like we discussed with Caesar’s cipher, there’s particular logic behind every encryption process that scrambles data. The encryption processes used today depend on highly complex mathematical algorithms that make it implicitly impossible to crack them.

You may not realize is that there are countless Symmetric key algorithms in existence! The most common encryption techniques include AES, DES, 3DES, RC4, RC5, RC6, etc.. Out of those algorithms, AES and DES algorithms are the best. While we can not cover all the various kinds of encryption algorithms, let us look at three of the most common.

  • DES Symmetric Encryption Algorithm

Launched in 1976, DES (data encryption standard) is among the oldest encryption methods. It has been officially adopted in 1977 to be used by federal agencies and was created by IBM to protect sensitive, unclassified digital government information. DES utilizes a 56-bit encryption key, and it is according to the Feistel Structure, which was created by Horst Feistel, a professional cryptographer. The DES encryption algorithm was one of those who were contained in TLS (transport layer security) versions 1.0 and 1.1.

DES translates 64-bit blocks of plaintext data into ciphertext by dividing the block into two different 32-bit blocks and applying the encryption processes to each. This entails 16 rounds of different processes –such as permutation, expansion, substitution, or an XOR operation using a round key –which the data goes through as encrypted. Finally, 64-bit blocks of encoded text are produced as the output signal.

Now, DES is no longer in use as many security researchers have cracked it. In 2005, DES was formally deprecated and replaced by the AES encryption algorithm. The biggest drawback to DES was its low encryption key length, which made brute-forcing lightly against it. TLS 1.2, the most commonly used TLS protocol today, doesn’t use the DES encryption method.

  • 3DES Symmetric Encryption Algorithm

3DES (also called TDEA, which stands for triple data encryption algorithm), as its name suggests, is an updated version of the DES algorithm which was released. 3DES has been put into use starting in the late 1990s and was created to overcome the drawbacks of the DES algorithm.

To accomplish this, it applies the DES algorithm thrice to every data block. This procedure made 3DES much harder to crack than its DES predecessor. Additionally, it became a popular encryption algorithm model in payment systems, standards, and technology in the finance market. It has also become a part of cryptographic protocols such as SSH, IPsec, TLS, and OpenVPN.

All encryption algorithms finally succumb to the power of time, and 3DES was no different. The Sweet32 vulnerability found by investigators Karthikeyan Bhargavan and Gaëtan Leurent unplugged the security holes which exist in the 3DES algorithm.

This discovery led the security industry to take into account the deprecation of this algorithm, and the National Institute of Standards and Technology (NIST) declared the deprecation at draft guidance published in 2019.  According to the draft, using 3DES is to be scrapped in most new applications after 2023. It’s also worth considering that TLS 1.3, the most recent norm for SSL/TLS protocols, also stopped using 3DES.

  • AES Symmetric Encryption Algorithm

AES, or “advanced encryption system,” is among the most prevalently used kinds of encryption algorithms and was designed as an alternative to the DES algorithm. Also called Rijndael, AES turn out to be an encryption standard on approval by NIST in 2001.

Unlike DES, AES is a family of block ciphers with ciphers of different key lengths and block sizes.  AES works on the methods of permutation and substitution.

First, the plaintext data is converted into blocks, and the encryption is applied using the encryption key. The encryption process includes various sub-processes such as shift rows, sub bytes, mix columns, and add-around keys. Depending on the size of the key, 10, 12, or 14, such rounds are performed. It is worth noting that the round will not include the sub-process of mix columns among all other sub-processes executed to encrypt the data.

The Benefit of Using the AES Encryption Algorithm

What all this boils down to is to state that AES is secure and flexible. AES is a much quicker algorithm than DES. The multiple key length options are the biggest asset you have as the longer the keys are, the more difficult it is to crack them.

AES is the encryption algorithm now used in many applications, such as:

  • Mobile app encryption,
  • Processor security and file encryption,
  • SSL/TLS protocol (website security),
  • Wi-Fi security,
  •  Wireless security,
  • VPN (a virtual private network), etc.

Government agencies, including the National Security Agency (NSA), rely upon the AES encryption algorithm to protect their sensitive information.


Second Kind of Encryption: Asymmetric Encryption

Asymmetric Encryption, compared to the symmetric encryption process, involves multiple keys for encryption and decryption. Asymmetric encryption includes two different encryption keys that are mathematically related to each other. One of these keys is named as the “public key” and another one as the “private key.” Hence, the asymmetric encryption procedure is also called “public-key cryptography.”

As we saw from the above example, symmetric encryption works excellent if Bob and Alice want to exchange info. Though what if Bob wants to communicate with hundreds of people? If he used different keys for each individual, would it be sensible? Not really, because that would be too many keys to keep track of.

Bob uses public-key encryption to resolve this problem, which means that he provides the public key to all the persons who send him the data and keeps the private key to himself. He directs them to encrypt the data with the public key so that the information can only be decrypted with the private key that he has. This removes the risk of key compromise as the data can only be decoded using the private key that Bob has.

What Makes Asymmetric Encryption an Excellent Technique

The first benefit of this type of encryption is the security it gives. While the decryption of the information is done using the private key, which has to be stored in this technique, the key — that is accessible — is used to encrypt the data. This helps to ensure that the data stays protected against man-in-the-middle (MiTM) strikes.

For email/web servers that connect to lacs of clients every minute, the asymmetric encryption method is nothing less than a boon as they only have to manage and protect a single key. Another point is that public-key cryptography supports creating an encrypted link without having to meet offline to exchange keys first.

The next feature that asymmetric encryption provides is authentication. The data encrypted by a public key can only be decrypted using the private key associated with it. It makes sure the information is seen and decrypted by the entity that’s supposed to receive it. In simpler terms, it verifies that you are talking to the person or organization that you think you are.

2 Main Kinds of Asymmetric Encryption Algorithms

1. RSA Asymmetric Encryption Algorithm

Composed by Leonard Adleman, Ron Rivest, and Adi Shamir (hence “RSA”) in 1977, RSA was, thus far, the most widely used asymmetric encryption algorithm. Its effectiveness lies in the “prime` factorization” method that it depends upon.

This system involves two large random prime numbers, and these amounts multiply to make another large number. The mystery here is to ascertain the original prime numbers from this number from this giant-sized multiplied number.

It seems this puzzle is virtually impossible — if using the right key length produced with enough entropy — for super-computers, let alone humans. In 2010, a group of investigators did a study. It took them over 1,500 years of calculating time (distributed across hundreds of computers) to decode RSA-768-bit key — that is way below the normal 2048-bit RSA key that is in use now.

The Benefit of Using the RSA Encryption Algorithm

A fantastic benefit that RSA offers is its scalability. It comes in various encryption key lengths like 768-bit, 1024-bit, 2048-bit, 4096-bit, etc.. Therefore, even if the reduced key-lengths are brute-forced, you may use encryption of greater key lengths because of the problem of brute-forcing the critical increases with every expanding key length.

RSA is based on a simple approach, and that is why its implementation in the public key infrastructure (PKI) becomes simple. This adaptability with PKI and its safety has made RSA the most popular asymmetric encryption algorithm used today. RSA is extensively utilized in several applications, such as crypto-currencies, SSL/TLS certificates, and email encryption.

2. ECC Asymmetric Encryption Algorithm

In 1985, two mathematicians named Victor S. Miller and Neal Koblitz proposed using elliptic curves in cryptography. After nearly two decades, their idea became a fact when ECC (Elliptic Curve Cryptography) algorithm entered to use in 2004-05.

An elliptic curve from the ECC encryption procedure shows the set of points that meets a mathematical equation (y2 = x3 + ax + b).

Like RSA, ECC also works on the rule of irreversibility. In simpler words, it’s simple to compute it in one direction but painfully hard to reverse it and come to the starting point. In ECC, a number representing a point on the curve is multiplied by another number and provides another point. To crack this mystery, you must work the point on the curve out. The mathematics of ECC is made so that it’s virtually impossible to get the new point, even if you know the original point.

The Benefit of Using the ECC Encryption Algorithm

Compared to RSA, ECC offers greater protection (against current procedures of cracking) as it is quite intricate. It provides a similar level of protection as RSA, but it uses much shorter key lengths. Consequently, ECC used with keys of larger lengths will take considerably more time to crack using brute force attacks.

Another benefit of the keys in ECC is faster performance. Shorter keys need less networking load and computing power, which turns out to be perfect for devices with limited processing and storage capacities.

It can help you load the website and reduces the time necessary to perform SSL/TLS handshakes when the ECC is used in SSL/TLS certificates.

The ECC algorithm is used for encryption processes, to apply digital signatures, in pseudo-random generators, etc..

However, the difficulty with using ECC is that several control panels and server software haven’t yet included a provision for ECC SSL/TLS certificates. We are assuming that this changes later on, but this implies that RSA is going to be the more commonly used asymmetric encryption algorithm meanwhile.

Hybrid Encryption: Symmetric + Asymmetric Encryption

First, let me explain that hybrid encryption isn’t a “method,” such as asymmetric and symmetric encryption are. It is taking the best from both of these methods and building synergy to build robust encryption systems.

As beneficial as asymmetric and symmetric encryption are, they both have their drawbacks. The symmetric encryption system works excellent for the fast encryption of extensive data. It does not provide identity verification, something that’s the requirement of the hour for online security. Asymmetric encryption — thanks to the private/public key pair — ensure that the data is accessed by your intended recipient. Although this verification makes the encryption method painfully slow when implemented at scale.

In most applications, such as website security, a need was to encrypt the data at high speed, and also the confirmation of identity was required to make sure the users that they are talking to the intended entity.

That’s how the notion of hybrid encryption was started. The hybrid encryption method is used in applications such as SSL/TLS certifications. SSL/TLS encryption is used during a set of back-and-forth communications between clients (browsers) and servers in a process called the “TLS handshake.” In this procedure, both parties’ identity is confirmed using the public and private keys. After both parties have confirmed their identities, the encryption of this data occurs through symmetric encryption with a temporary (session) key. This guarantees fast transmission of the loads of data that we send and receive on the internet every second.

Kinds of Encryption Approaches

If you are wondering which type of encryption is better than another, then there won’t be any clear winner as both asymmetric and symmetric encryption brings their benefits to the table, and we cannot select only one at the cost of the other.

From the security aspect, asymmetric encryption is undoubtedly better as it guarantees non-repudiation and authentication. Although, the performance is also an aspect that we can’t afford to ignore, and that’s why symmetric encryption will always be needed.

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