Polymorphic Encryption Algorithms (2016)

Off-the-shelf encryption algorithms

There is a wide variety of encryption algorithms available. The advantage of these algorithms is that they are heavily studied and their strengths and weaknesses are known. The first type are block cipher algorithms (data is encrypted in blocks of fixed size), including:

• AES (Rijndael)
• Blowfish
• Twofish
• DES
• Serpent
• TEA – Tiny Encryption Algorithm
• RC5 , RC6

There are also stream cipher algorithms (which encrypt data one byte at a time), such as the popular RC4 algorithm. Most encryption algorithms are symmetric, which means that the same key is used for both encrypting and decrypting data. However, there are a number of asymmetric encryption functions, based on public key infrastructure. This group of algorithms includes:

• RSA
• ElGamal
• ECC

The encryption component of these algorithms uses a public key , while the decryption component requires a private key . As the name implies, public keys can be safely published on the Internet (like the keys in the PGP encryption system). Unlike symmetric encryption algorithms, where a leaked key means anyone can read the message, asymmetric encryption algorithms ensure that only the holder of the private key can decrypt the message. Since the public and private keys are mathematically related, it is theoretically possible to “crack” a public key and obtain the private key, however there are no known practical ways of doing this. In the case of RSA, cracking the public key involves splitting it into its two prime factors (RSA public keys are the product of two very large prime numbers). This factoring process currently takes an enormous time. The RSA company even organized a public challenge to break RSA keys , where the largest prize was $US200,000 for cracking a 2048-bit key.

All the above algorithms are extensively documented, and implementations can easily be found for many programming languages.