Encryption Standards: AES, RSA, ECC, SHA and Other Protocols

Encryption is the process of encoding data in such a way that only authorized parties can access it. There are several encryption standards and protocols used today to secure data in motion and at rest. Some of the most widely used and important encryption standards include:

Advanced Encryption Standard (AES)

AES is a symmetric encryption algorithm standardized by the National Institute of Standards and Technology (NIST) in 2001. It is based on the Rijndael cipher developed by Belgian cryptographers. AES has a fixed block size of 128 bits and supports key sizes of 128, 192, and 256 bits.

How AES Works

• AES operates on a 4×4 matrix of bytes called the state.

• For encryption, the plaintext is copied into the state array. Several successive rounds of four different transformations are applied to the data in the state array. These include:
  ---> SubBytes - Non-linear byte substitution using a substitution table
  ---> ShiftRows - Cyclic shift of row contents
  ---> MixColumns - Column-wise mixing operation using mathematical function
  ---> AddRoundKey - Round key added to state using XOR

• The number of rounds depends on the key size - 10 rounds for 128-bit keys, 12 rounds for 192-bit keys and 14 rounds for 256-bit keys.

• After the final round, the ciphertext is read from the state array. Decryption applies the inverse transformations in reverse order.

Advantages of AES

• Very high security - no known practical attacks exist
• Performance - efficient in software and hardware implementations
• Flexible key size - 128, 192 or 256 bit keys
• Widely adopted and implemented in protocols and standards like TLS, SSH, IPsec, WiFi security

AES is used ubiquitously today by organizations and individuals to encrypt sensitive data. It is approved by the US government for protecting classified data up to the level of TOP SECRET.

RSA

RSA is a public-key encryption algorithm based on mathematical problems involving prime factorisation. It was invented by Ron Rivest, Adi Shamir and Leonard Adleman in 1977.

How RSA Works

• RSA involves a public and private key pair. The public key is made public while the private key is kept secret.
• The key pair is generated from two large prime numbers picked at random. Mathematical operations are performed on the primes to generate the public and private keys.
• For encryption, the plaintext is encrypted using the public key. The ciphertext can only be decrypted using the private key.
• For digital signatures, the private key is used to sign the message. The signature can be verified using the public key.

Advantages of RSA

• Very secure if large enough keys are used (e.g. 2048 bits or more)
• Scalable and flexible to use with different key sizes
• Widely used for secure data transmission and digital signatures
• Supported in standards like PKCS, TLS, SSH, S/MIME, PGP

RSA is commonly used for encrypting session keys and digital signatures due to its security and scalability. Many protocols use RSA encryption as part of their security measures.

Diffie-Hellman Key Exchange

Diffie-Hellman is a method for securely exchanging cryptographic keys over an insecure channel. It was developed by Whitfield Diffie and Martin Hellman in 1976.

How Diffie-Hellman Works

• Alice and Bob agree on a large prime number 'p' and a generator 'g' which is a primitive root modulo p.
• Alice chooses a secret integer 'a' and sends Bob 'ga mod p'.
• Bob chooses a secret integer 'b' and sends Alice 'gb mod p'.
• Alice computes (gb)a mod p. Bob computes (ga)b mod p.
• The result of the equations is their shared secret 'gab mod p' which can be used as an encryption key.

Advantages of Diffie-Hellman

• Provides perfect forward secrecy since new keys are generated for each session
• Computationally fast and efficient
• Prevents man-in-the-middle attacks as the shared key is never transmitted
• Used in protocols like TLS, SSH, VPNs, etc. to establish secure channels

Diffie-Hellman enables two parties to securely establish a shared secret key over an insecure medium like the internet.

Elliptic Curve Cryptography (ECC)

ECC is a public key algorithm based on elliptic curve mathematics that can create faster, smaller and more efficient cryptographic keys.

How ECC Works

• ECC relies on properties of the elliptic curve equation instead of large prime numbers.
• Smaller ECC keys (256-bit) offer the same security as larger keys in other systems (e.g. 2048-bit RSA).
• ECC keys are generated by picking a random point on the elliptic curve. The public key is derived from this point while the private key is derived from the random number used to generate the point.
• For encryption, the plaintext is encrypted using the public key while decryption uses the private key. Digital signatures also follow the similar process.

Advantages of ECC

• Smaller key sizes leading to faster computations, lower power usage and memory
• Stronger security per bit compared to other algorithms
• Used in protocols like TLS, SSH, Bitcoin to enable efficient and secure transactions

ECC enables the use of smaller, more efficient cryptographic keys while ensuring strong security. This makes it suitable for constrained environments like mobile devices and embedded systems.

Secure Hash Algorithms (SHA)

Hash functions like SHA are used to generate fixed-length message digests from input data. These digests protect integrity as any change to the input will affect the hash value.

How SHA Works

• SHA accepts an input message of any length and processes blocks of 512 bits at a time.
• SHA uses compression functions that iteratively process each 512-bit block to scramble and condense the input data.
• Additional rounds of hashing and bit operations are applied to produce the final digest.
• Popular SHA variants are SHA-1 (160-bit digest), SHA-2 (256-bit digest) and SHA-3 with 224, 256, 384 or 512-bit digest sizes.

Advantages of SHA

• Widely used to verify data integrity and for digital signatures.
• Resistant to preimage and second preimage attacks.
• Standardized and commonly implemented in software and hardware.
• Allows use of higher security variants like SHA-2 and SHA-3 as they emerge.

Secure hash algorithms like SHA protect sensitive data and communications from unauthorized changes. They are vital components in blockchain, version control, IT security and other applications.

Blowfish

Blowfish is a symmetric encryption cipher developed by Bruce Schneier. It has a 64-bit block size and supports key lengths from 32 to 448 bits.

How Blowfish Works

• It splits messages into 64-bit blocks and encrypts them separately.
• It uses a Feistel network with 16 rounds of encryption.
• Each round applies XOR operations, substitutions using S-boxes and permutations based on the key.
• Decryption applies the identical process using the same key but reversing the order of permutations and using inverse S-boxes.

Advantages of Blowfish

• Compact, simple, fast and easy to implement in software.
• Secure against differential and linear cryptanalysis attacks.
• Flexible key length and publicly available algorithm.
• Unpatented and license-free which allows free usage.

Blowfish provides good encryption at fast speeds for a variety of applications ranging from ecommerce to system tools and databases.

Pretty Good Privacy (PGP)

PGP is a public key cryptography system that provides encryption and decryption using a variety of algorithms.

How PGP Works

• Uses public key cryptography to protect emails, files, directories etc.
• Provides authentication, confidentiality, data compression and hashing functions.
• Uses digital certificates, digital signatures and key servers for identity verification.
• Combines symmetric key cryptography and public key cryptography for performance.
• Wide range of encryption algorithms (IDEA, 3DES, AES, etc.) and hash functions supported.

Advantages of PGP

• Highly secure and provides end-to-end encryption.
• Open standard that anyone can implement based on published specifications.
• Compatible with S/MIME, LDAP, HTTPS and other protocols and standards.
• Available in both commercial and free open-source versions like GnuPG.

PGP enables secure email communication and data storage for individuals as well as enterprises. It provides comprehensive encryption and signing functions for emails, files, directories and disk volumes.

Frequently Asked Questions

Which encryption standard is the most secure?
AES is considered among the most secure encryption standards available today, especially with 256-bit keys. RSA, ECC, SHA-2 are also highly secure when used with sufficiently long key lengths.

What is the difference between symmetric and asymmetric encryption?
Symmetric algorithms like AES use the same key for encryption and decryption while asymmetric algorithms like RSA use different public and private keys.

Which key size should be used for encryption?
For symmetric encryption, AES with 256-bit keys offers excellent security. For RSA, 2048-bit keys or higher are recommended. With ECC, 256-bit keys provide adequate security.

Can broken encryption standards like MD5 still be used?
MD5 and SHA-1 are considered cryptographically broken and should not be used for security purposes. AES, SHA-2/SHA-3 should be used instead wherever possible.

Which encryption standard is fastest in performance?
Symmetric algorithms like AES and Blowfish offer very good performance and speed across software and hardware. ECC is faster than RSA when equivalent key sizes are compared.