mywiki:encryption:encryption:start
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Table of Contents
Encryption
| Reference | Block Cipher mode |
|---|
Ciphers
| Ciphers By type of key | Description | Example |
|---|---|---|
| Block Cipher | Break messages into fixed length blocks, and encrypt each block using the same key | (3)DES, AES/Rijndael, IDEA |
| Stream Cipher | Break message into fixed length blocks, but use a sequence of keys to encrypt the blocks | Vigenère cipher, RC4, SEAL |
| Stream Cipher | Description |
| Synchronous Stream Ciphers | generates the key string from a source other than the message itself |
| Self-Synchronous Stream Ciphers | obtain a key from the message itself |
| Cipher by the type of input data | Description | |
|---|---|---|
| symmetric key algorithms | the same key is used for encryption and decryption | DES, AES |
| asymmetric key algorithms | two different keys are used for encryption and decryption | RSA |
| Modes of Operation | Descriptions | Examples |
| Electronic Codebook Mode (ECB Mode) | ||
| Cipher-Block Chaining Mode (CBC Mode) | ||
| Counter Mode (CTR Mode) | ||
| Output Feedback Mode (OFB Mode) |
| Cryptographic hash functions |
| digital signatures |
| message authentication codes (MACs) |
IPSEC
IPsec uses two types of algorithms
- authentication algorithms
- encryption algorithms
authentication/Integrity algorithms: use a shared key to verify the identity of the sending IPsec device. The IPsec protocol suite defines two authentication algorithms: MD5 and SHA-1. The Services Router uses an HMAC variant of MD5 and SHA-1 algorithms that provide an additional level of hashing. AES-GMAC 128, 192, and 256, AES-GCM 128, 192, and 256
Encryption algorithms: use a shared key to verify the authenticity of the IPsec devices. 1) DES, 3DES, 2) AES-CBC 128, 192, and 256, 3) AES-GCM 128, 192, and 256.
Note: AES-GCM is both an integrity and encryption algorithm and is described in the Integrity algorithms section.
Common Terms
| DES | Data Encryption Standard |
| AES | Advanced Encryption Standard |
| plaintext | the original message |
| ciphertext | the coded message |
| cipher | algorithm for transforming plaintext to ciphertext |
| key | info used in cipher known only to sender/receiver |
| encipher (encrypt) | converting plaintext to ciphertext |
| decipher (decrypt) | recovering ciphertext from plaintext |
| cryptography | study of encryption principles/methods |
| cryptanalysis (codebreaking) | the study of principles/ methods of deciphering ciphertext without knowing key |
| cryptology | the field of both cryptography and cryptanalysis |
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