Symmetric Encryption Algorithms
DES (Data Encryption Standard): One of the earliest encryption standards FIPS (Federal Information Processing Standard): The DES that was adopted as a federal standard for encrypting and securing government data
- DES is a symmetric block cipher that uses 64 bit key sizes and operates on blocks 64 bits in size.
- Though key size is technically 64 bits in length, eight bits are used only for parity checking. A simple form of error checking.
- This means that real-world key length for DES is only 56 bits
- This means that there are a maximum of 2^56 power or 72 quadrillion possible keys Key length is super-important in cryptography since it essentially defines the maximum potential strength of the system
Advanced Encryption Standard (AES): The first and only public cipher that’s approved for use with top secret information by the United States National Security Agency
- AES is also a symmetric block cipher similar to DES, in which it replaced.
- AES uses 128 bit blocks, twice the size of DES blocks and supports key length of 128 bit, 192 bit, or 256-bit.
- Because of the large key size, brute-force attacks on AES are only theoretical right now because the computing power required or time required using modern technology exceeds anything feasible today.
An important thing to keep in mind when considering various encryption algorithms is speed and ease of implementation.
- Ideally, an algorithm shouldn’t be overly difficult to implement because complicated implementation can lead to errors and potential loss of security due to bugs introduced in implementation.
- Speed is important because sometimes data will be encrypted by running the data through the cipher multiple times.
modern CPUs from Intel or AMD have AES instructions built into the CPUs themselves. This allows for far greater computational speed and efficiency when working on cryptographic workloads.
RC4 (Rivest Cipher 4): Asymmetric stream cipher that gained widespread adoption because of its simplicity and speed
- RC4 supports key sizes from 40 bits to 2048 bits. So the weaknesses of RC4 aren’t due to brute-force attacks, but the cipher itself has inherent weaknesses and vulnerabilities that aren’t only theoretically possible.
- RC4 was used in a bunch of popular encryption protocols, like WEP for wireless encryption and WPA, the successor to WEP.
- It was also supported in SSL and TLS until 2015 when RC4 was dropped in all versions of TLS because of inherent weaknesses
TLS 1.2: The current recommended revision of SSL
SSL 3.0: The latest revision of SSL that was deprecated in 2015
For more information about symmetric encryptions, check out the following link here.