Difference Between RC4 and AES

RC4 is a stream cipher and variable-length key algorithm.The main difference between RC4 and AES is that AES is a block cipher and RC4 is a stream cipher. Symmetric algorithm classes include block encryption and stream encryption. A block cipher encodes plain text in block sizes, whereas a stream cipher encodes bit by bit, simulating the flow of a stream.

Rivest Cipher 4 (RC4)

Ron Rivest invented Rivest Cipher 4 in 1987. He developed it to consistent RSA security. The first design, commonly referred to as the Verman cipher, was inspired by a one-time pad. RC4 is a symmetric method like AES, however unlike AES, it is a stream cipher.

Rivest Cipher 4’s encryption was kept secret until the code was published in the public domain in 1994. RC4 is a byte-oriented stream cipher. Bit by bit, encrypt the data. Key sizes are 64-bit or 128-bit. To generate the ciphertext, the encryption procedure uses a secret key and the RC4 algorithm.

The keystream in RC4 is generated by KSA and PRGA. KSA is an abbreviation for Key Scheduling Algorithm, and PRGA is an abbreviation for Pseudo-Random Generation Algorithm.

Types of Rivest Cipher 4

• Splash
• RC4A
• VMPC
• RC4A+

Applications Area of RC4

• SSL
• WEP
• TLS
• WPA 

Advanced Encryption Standard (AES)

The National Institute of Standards and Technology (NIST) which was given an open competition in 1997. Cryptologists from across the countries were given chance to share their algorithms. They had to meet the AES standards. In 1999, each of the algorithms were examined to see which was the best fit, and Rijndael was ultimately picked.

The AES block cipher employs a symmetric key. To convert plain text to ciphertext, it is encoded in block sizes. The bit size is limited to 128 bits, with key sizes ranging from 128, 192, and 256 bits. The size of the key influences rounding.

So, considering the 10 rounds for the 128 bits, then 12 rounds for the 192 bits, and 14 rounds for 256 bits. These were known popularly as AES128, AES192, and AES256.

In every round of the encryption process involves of four phases. The higher rounds there are, the more difficult it is to crack the encryption code. Likewise a symmetric key is being used, which is implying that a unique key is provided by both the user and the recipient.

Some High-Security Conditions by National Institute of Standards as follows:

1. It must be a symmetric key cryptography algorithm.
2. AES should have two separate keys that can be adjusted.
3. AES should always be designed in such a way that it can be integrated into all hardware and software.
4. The general population must determine the definition of AES.

Tabular Differences Between AES and RC4

Parameters	RC4	AES
Type	Stream Cipher	Block Cipher
Key	Variable-length (1-256 bytes)	Fixed length (128, 192, or 256 bits)
Mode	Not Applicable	Multiple (e.g. CBC, ECB, CTR, etc.)
Speed	Fast	Slower than RC4
Security	Vulnerable to key-related attacks	Highly secure
Encryption/Decryption	Symmetric	Symmetric
Block Size	Not Applicable	128 bits
Key Schedule	Weak, susceptible to related key attacks	Strong, resistant to related key attacks.
Use	Legacy systems, low-security applications.	Modern cryptography, high-security applications.

Conclusion

In conclusion, RC4 and AES are two different encryption algorithms that serve different purposes. The main difference between AES and RC4 is that AES is a block cipher and RC4 is a stream cipher. Symmetric algorithm classes include block encryption and stream encryption. A block cipher encodes plain text in block sizes, whereas a stream cipher encodes bit by bit, simulating the flow of a stream.