Block Cipher Schemes

Table of Contents

## Which are the block ciphers?

Block Cipher Schemes

- Digital Encryption Standard (DES) − The popular block cipher of the 1990s.
- Triple DES − It is a variant scheme based on repeated DES applications.
- Advanced Encryption Standard (AES) − It is a relatively new block cipher based on the encryption algorithm Rijndael that won the AES design competition.

## What is the best block cipher?

Best Encryption Algorithms

- AES. The Advanced Encryption Standard (AES) is the trusted standard algorithm used by the United States government, as well as other organizations.
- Triple DES.
- RSA.
- Blowfish.
- Twofish.
- Rivest-Shamir-Adleman (RSA).

**How many block ciphers are there?**

There are five types of operations in block cipher modes, ECB (Electronic Code Block) mode, CBC (Cipher Block Chaining) mode, CFB (Cipher Feedback) mode, OFB (Output Feedback) mode and CTR ( Counter) mode.

**How do you decode a block cipher?**

During decrypting of a ciphertext block, one should add XOR the output data received from the decryption algorithm to the previous ciphertext block. Because the receiver knows all the ciphertext blocks just after obtaining the encrypted message, he can decrypt the message using many threads simultaneously.

### Where are block ciphers used?

Block ciphers have been widely used since 1976 in many encryption standards. As such, for a long time cracking these ciphers became the top priority of cipher crackers everywhere. Block ciphers provide the backbone algorithmic technology behind most modern-era ciphers.

### Is GCM better than CTR?

In simple terms, Galois Counter Mode (GCM) block clipper is a combination of Counter mode (CTR) and Authentication it’s faster and more secure with a better implementation for table-driven field operations. GCM has two operations, authenticated encryption and authenticated decryption.

**Can quantum computers break AES 256?**

Symmetric encryption, or more specifically AES-256, is believed to be quantum-resistant. That means that quantum computers are not expected to be able to reduce the attack time enough to be effective if the key sizes are large enough.

**Is Blowfish a block cipher?**

Blowfish is a symmetric-key block cipher, designed in 1993 by Bruce Schneier and included in many cipher suites and encryption products. Blowfish provides a good encryption rate in software, and no effective cryptanalysis of it has been found to date.

#### How do block ciphers work?

Block Cipher

- A block cipher encrypts data in blocks using a deterministic algorithm and a symmetric key.
- As in the case of stream ciphers, most encryption methods encrypt bits one by one (stream ciphers).
- A 128-bit block cipher brings 128 bits of plaintext and encrypts it into 128 bits of ciphertext.

#### What is CBC and CTR?

CBC, OFB and CFB are similar, however OFB/CFB is better because you only need encryption and not decryption, which can save code space. CTR is used if you want good parallelization (ie. speed), instead of CBC/OFB/CFB. XTS mode is the most common if you are encoding a random accessible data (like a hard disk or RAM).