📝Block cipher mode of operation

tags

§ Cryptography

• Block ciphers can be used securely to encrypt a single fixed-size block of data.

• A mode of operation describes how to apply a block cipher to transform data large than one block.

• Initialization Vector (IV) is an important aspect of many modes of operation.

• Because block ciphers work on fixed-size blocks, many modes of operation require padding.

• Modes

  • Electronic Codebook (ECB): the simplest mode of operation. Many security drawbacks. Not recommended.

  • Cipher Block Chaining (CBC): a better mode of operation. Fixes data patterns hiding and randomizes encryption process so that encrypting the same input twice produces different ciphertext.

  • Propagating Cipher Block Chaining (PCBC): a variation of CBC that is not commonly used.

  • Cipher Feedback (CFB): a self-synchronizing streaming mode of operation.

  • Output Feedback (OFB): a simple synchronous streaming mode of operation.

  • Counter (CTR): a streaming mode of operation that allows random access on encryption/decryption.

  • Galois/Counter Mode (GCM) and GMAC: improvement of CTR with added authentication. It can also be used for message authentication only.

Backlinks

• 📝 Galois/Counter Mode (GCM) and GMAC
• 📝 Counter (CTR)
• 📝 Output Feedback (OFB)
• 📝 Cipher Feedback (CFB)
• 📝 Propagating Cipher Block Chaining (PCBC)
• 📝 Padding (Encryption)
• 📝 Initialization Vector
• 📝 Cipher Block Chaining (CBC)
• 📝 Electronic Codebook (ECB)
• 📝 § Cryptography