"A block cipher is a deterministic algorithm that operates on fixed-length groups of bits, called blocks."
A type of encryption that encrypts data one block at a time.
Cryptography basics: Understanding the basics of cryptography, including encryption, decryption, and key generation, is crucial when learning about block ciphers.
Symmetric Key Encryption: Symmetric key encryption is a model in which the sender and receiver share the same key for encrypting and decrypting data.
Block Ciphers: Block ciphers are a symmetric key encryption technique that encrypts data in fixed-size blocks.
Data Encryption Standard (DES): DES is a block cipher algorithm that operates on 64-bit blocks and has a key size of 56 bits.
Advanced Encryption Standard (AES): AES is a block cipher algorithm that is widely used in modern cryptography. It operates on 128-bit blocks and has a key size of 128, 192, or 256 bits.
Modes of Operation: Modes of operation describe how a block cipher algorithm can be used to encrypt data in real-world applications.
Electronic Code Book (ECB): ECB is a mode of operation for block ciphers that encrypts each block of data independently.
Cipher Block Chaining (CBC): CBC is a mode of operation for block ciphers that encrypts each block of data using the previous block's cipher text.
Output Feedback (OFB): OFB is a mode of operation for block ciphers that turns a block cipher into a stream cipher, allowing it to encrypt data in real-time.
Counter (CTR): CTR is a mode of operation for block ciphers that uses a counter to generate a key stream that is XORed with the input data.
Cryptographic Attacks: Understanding how attackers can attempt to break a block cipher algorithm is essential in understanding how to choose, implement and use them securely.
Differential Cryptanalysis: Differential cryptanalysis is a method used to break symmetric key encryption methods, including block ciphers.
Linear Cryptanalysis: Linear cryptanalysis is a method used to break symmetric key encryption methods, including block ciphers.
Avalanche Effect: The Avalanche Effect is a feature of cryptographically secure systems, where even small changes to the input data lead to significant differences in the output.
Key Exchange: Key exchange is the process by which two parties negotiate a shared secret key for use in symmetric key encryption.
Public Key Cryptography: Public key cryptography is a model in which the sender and receiver use different keys for encrypting and decrypting data.
Digital Signatures: Digital signatures are a method of verifying the authenticity and integrity of digital documents using public key cryptography.
Hashing Algorithms: Hashing algorithms are a type of cryptographic function that generates a fixed size output (hash) from any size input.
Message Authentication Codes (MACs): MACs are cryptographic techniques used to provide assurance that a message has not been tampered with during transit.
Cryptographic Protocols: Cryptographic protocols may include a combination of any of the above topics, used together to provide secure communication. These may include secure email protocols, secure messaging protocols among others.
Data Encryption Standard (DES): This is a symmetric block cipher which uses a 64 bit key length and a fixed block size of 64 bits. DES is one of the oldest and most widely used block ciphers.
Triple DES (3DES): This is a symmetric block cipher that is derived from DES. It uses three keys instead of one, which gives it a longer key length and higher level of security than DES.
Advanced Encryption Standard (AES): This is a symmetric block cipher which uses a variable key length from 128 bits to 256 bits and can support block sizes of 128, 192, and 256 bits. AES is widely used in both general and military applications.
Blowfish: Developed by Bruce Schneier, this symmetric block cipher uses a variable-length key from 32 to 448 bits and is designed to be highly secure and very efficient.
Twofish: This is a symmetric block cipher which uses a variable key length of between 128 and 256 bits and is known for its resistance to various cryptanalytic attacks.
RC4 (Rivest Cipher 4): This is a stream cipher which was designed to be used for software encryption. It is known for its speed and simplicity.
Serpent: This is a symmetric block cipher which uses a key length of 128, 192, or 256 bits and supports block sizes of 128, 192, and 256 bits.
AES-NI (AES New Instructions): This is a hardware-based encryption standard which uses AES to accelerate encryption and decryption in Intel processors.
Camellia: This is a symmetric block cipher which uses key lengths of 128, 192, or 256 bits and supports block sizes of 128, 192, and 256 bits. It is used mainly in Japan and is supported by many security protocols.
GOST: This is a symmetric block cipher which is widely used in Russia and other former Soviet countries. It uses a variable key length from 32 to 256 bits and supports block sizes of 64 bits.
IDEA (International Data Encryption Algorithm): This is a symmetric block cipher which uses a 128-bit key and supports block sizes of 64 bits.
CAST (Carlisle Adams and Stafford Tavares): This is a symmetric block cipher which uses a variable-length key and supports block sizes of 64 bits.
Skipjack: This was originally developed for the U.S. government and uses a 80-bit key and a 64-bit block size. It is no longer used due to security concerns.
Square: This is a symmetric block cipher which uses a variable-length key and supports block sizes of 128 and 256 bits.
MARS (Matrix of Advanced Encryption Standard): This is a symmetric block cipher which uses a 128, 192, or 256-bit key and supports block sizes of 128, 192, or 256 bits.
AES-GCM (Authenticated Encryption with Associated Data): This is a symmetric block cipher which uses AES encryption and provides authentication of encrypted data along with confidentiality.
ChaCha20: This is a symmetric stream cipher which is designed to be very fast and secure. It is often used in online communications and is supported by many security protocols.
Salsa20: This is a symmetric stream cipher which is similar to ChaCha20 and is known for its speed and simplicity.
HC-128 (Hongjun Wu stream cipher): This is a symmetric stream cipher which uses a key length of 128 bits and a 128-bit initialization vector. It is designed to be highly secure and fast.
Rabbit: This is a symmetric stream cipher which uses a 128-bit key and a 64-bit IV. It is known for its speed and efficiency.
ZUC: This is a symmetric stream cipher which was designed for use in China. It uses a key length of 128 bits and supports block sizes of 128 bits.
"Block ciphers are the elementary building blocks of many cryptographic protocols."
"They are ubiquitous in the storage and exchange of data."
"A block cipher uses blocks as an unvarying transformation."
"No, even a secure block cipher is suitable for the encryption of only a single block of data at a time."
"A fixed key is required to use a block cipher for encryption."
"The security goals of confidentiality and authenticity can be achieved."
"Yes, a multitude of modes of operation have been designed to allow their repeated use in a secure way."
"Block ciphers may also feature as building blocks in other cryptographic protocols, such as universal hash functions and pseudorandom number generators."
"Yes, the fixed-length groups of bits are called blocks."
"A block cipher is a deterministic algorithm, meaning it produces the same output for a given input every time."
"The security goals of confidentiality and authenticity can be achieved."
"Block ciphers are suitable for the encryption of only a single block of data at a time."
"Modes of operation have been designed to allow their repeated use in a secure way."
"They are ubiquitous in the storage and exchange of data."
"Block ciphers may also feature as building blocks in other cryptographic protocols, such as universal hash functions and pseudorandom number generators."
"A block cipher is... authenticated via encryption."
"No, a block cipher operates on fixed-length groups of bits, called blocks."
"A fixed key is required to use a block cipher for encryption."
"Yes, block ciphers may also feature as building blocks in other cryptographic protocols."