RC4 vs AES: Difference and Comparison

Over the network, security is necessary to transmit confidential information in today’s world. Also, safety is demanding in a range of applications.

The cryptographic algorithms have a chief role in offering data security in case of malicious attacks.  

They consume a notable amount of computing resources like memory, encryption time, CPU time, etc. Algorithms of the symmetric key are used over asymmetric key as they are fast.

Stream cipher and block cipher algorithms are two categories of symmetric algorithms. In this article, the chief focus is on differentiating RC4 and AES. 

Key Takeaways

  1. RC4 is an older stream cipher encryption algorithm, while AES is a more modern, widely adopted block cipher encryption standard.
  2. AES is considered more secure than RC4 due to its robustness against cryptographic attacks and larger key sizes.
  3. Many organizations and industries have moved from RC4 to AES for enhanced Security and compliance with current encryption standards.

RC4 vs AES 

RC4 is a stream cipher that uses variable-length keys, while AES is a block cipher that uses fixed-length keys. They are widely used as web browsers, wireless networks, and credit card transactions. AES offers better security than RC4 due to its larger key size and more efficient design.

RC4 vs AES

RC4 Is a type of stream that runs on data a byte to encrypt that data.

Among the stream ciphers, it is one of the most commonly used in transport layer security (TLS)/ Secure Socket Layer (SSL) protocols, the Wi-Fi Security Protocol WEP, and IEEE 802. 11 wireless LAN standard.  

The AES is a symmetric block cipher chosen to protect categorized information by the U.S. government. Throughout the world, the implementation of AES is in hardware and software to encrypt sensitive data.

The AES is crucial for government cybersecurity, computer security, and electronic data protection. 

Comparison Table

Parameters of ComparisonRC4AES
Full formRivest Cipher 4Advanced Encryption Standard
Key sizes256, 192, and 128 bits128 or 64 bits
SecurityLess secureMore secure
First published19941998
DesignersRon RivestVincent Rijmen and Joan Daemen

What is RC4? 

In cryptography, RC4 is extraordinary for its speed and software vulnerabilities simplicity in a number that has been discovered, providing it insecure.

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It is specifically exposed when the outputs keystream’s beginning is not discarded or related, or non-random keys are used.

There is speculation as of 2015 that some state agencies of cryptography might possess the potential to break RC4 when used in the TLS.

IETE’s protocol has published RFC 7465 to exclude the usage of RC4 in TLS; Microsoft, as well as Mozilla, have issued similar recommendations.

The most vital RC4’s weakness comes from the key, schedule inadequacy; the first bytes of output exhibit information related to the key. Alongside simply discarding part of the outfit stream’s primary portion this can be corrected.

This is referred to as RC4- DropN, in which N is a multiple of 256 like 1024 or 768.

In contrast to a modern stream cipher, RC4 crashes to take a distinguish nonce alongside the key.

It simply means that when a solo long-term key is to be used to cipher multiple streams safely, the protocol describes how to merge the long-term key as well as a nonce to build the stream key for RC4.

What is AES? 

The AES is also known by its traditional name, namely, Rijndael.

Rijndael is a cipher family with different block and key sizes. For AES, the NIST selected three Rijndael family members, each with 128-bit block size but three distinctive key lengths namely, 256, 192, and 128 bits.  

By the US government, the AES has been adopted and supersedes the DES (Data Encryption Standard), which was introduced in 1977.

AES described the algorithm as an asymmetric key algorithm which means the same key is used for both decrypting and encrypting the data.  

Low RAM and high-speed requirements were criteria of the selection process of AES. AES performs well on a range of hardware, from high-performance computers to 8-bit smartcards.

AES encryption needed 18 clock cycles per byte on a Pentium Pro, which is equivalent to a throughput of 11 MiB/s for a processor of 200 MHz.  

On May 26, 2002, AES became the effective standard of the U.S. federal government after approval by U.S. Commerce Secretary. It is available in many distinctive packages.

It is the first publicly approachable cipher approved by the NSA of the U.S. for top-secret information. 

Main Differences Between RC4 and AES 

  1. Since RC4 was initially a trade secret, which some people come up with inventive methods to call the leaked description traced back to 1994, just like ARC4 and ARCFOUR. On the flip side, AES is available publicly, and without hitting any legal problem, can be freely used.  
  2. The chief reason behind RC4 popularity is that it can be very fast and simple to use. On the other hand, the implementation of AES in hardware is becoming popular as it offers speed metrics over software implementations.  
  3. The advantages of RC4 are is that it does not require more memory, implemented on large streams of data, strong in coding, and easy to implement. In contrast, robust algorithm, high security, best open encryption solution, and implementation on both software and hardware are some of the advantages of AES.  
  4. In terms of disadvantages, RC4 fails to offer authentication, is not used with strong MAC, and requires additional analysis before comprising a new system. On the contrary, many rounds for encryption requirements need much processing at different stages, and hard to implement on software are some of the disadvantages of AES.  
  5. RC4 is a stream cipher that fails to have a discrete block size. It uses pseudorandom bit’s keystream that is combined to the data utilize an exclusive OR (XOR). Meanwhile, AES is a block cipher that runs on data’s discrete blocks utilizing a fixed formula and key. 
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  1. https://link.springer.com/article/10.1007/s10623-008-9206-6
  2. https://www.cs.miami.edu/home/burt/learning/Csc688.012/rijndael/rijndael_doc_V2.pdf

Last Updated : 13 July, 2023

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