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ADSL | asymmetric digital | PGP | Pretty Good Privacy |

subscriber line | PING | packet internet groper | |

DES | Data Encryption Standard | PSTN | public switched telephone |

DMZ | demilitarised zone | network | |

DNS | domain name system | RC2 | Rivest cipher 2 |

DSS | Digital Signature Standard | RC4 | Rivest cipher 4 |

FTP | file transfer protocol | RSA | Rivest, Shamir and |

IANA | Internet Assigned Numbers | Adleman block cipher | |

Authority | S-HTTP | secure hypertext transfer | |

ICMP | internet control message | protocol | |

protocol | S/MIME | secure/multipurpose internet | |

IDEA | International Data | mail extensions | |

Encryption Algorithm | SET | secure electronic transaction | |

IP | internet protocol | SHA | secure hash algorithm |

IPSec | internet protocol security | SIM | subscriber identity module |

ISDN | integrated services digital | SMTP | simple mail transfer |

network | protocol | ||

ISO | International Organization | TCP | transmission control |

for Standardization | protocol | ||

LAN | local area network | UDP | user datagram protocol |

MD5 | message digest 5 | VPN | virtual private network |

MSP | message security protocol | XOR | exclusive-OR |

NSA | National Security Agency | 3DES | Triple Data Encryption |

OSI | open systems | Standard | |

interconnection |

Algorithm | Description |
---|---|

DES (Data Encryption Standard) | A block cipher with a 56-bit key. Adopted in 1977 by the US National Security Agency (NSA) as the US Federal standard, it has been one of the most widely used encryption algorithms but, as computers have become more powerful, it is now considered to have become too weak. |

Triple-DES (or 3DES) | A variant of DES developed to increase its security. It has several forms; each operates on a block three times using the DES algorithm, thus effectively increasing the key length. Some variants can use three different keys, the same key three times, or use an encryption–decryption–encryption mode. |

IDEA(International Data Encryption Algorithm) | A block cipher with a 128-bit key published in 1990. It encrypts data faster than DES and is considered to be a more secure algorithm. |

Blowfish | A compact and simple block cipher with a variable-length key of up to 448 bits. |

RC2 (Rivest cipher no. 2) | A block cipher with a variable-length key of up to 2048 bits. The details of the algorithm used have not been officially published. |

RC4 (Rivest cipher no. 4) | A stream cipher with a variable-length key of up to 2048 bits. |

Algorithm | Description |
---|---|

RSA (named after its creators–Rivest, Shamir and Adleman) | A block cipher first published in 1978 and used for both encryption and authentication. Its security is based on the problem of factoring large integers, so any advances in the mathematical methods of achieving this will affect the algorithm's vulnerability. |

DSS (Digital Signature Standard ^{1}) | Developed by the US National Security Agency (NSA). Can be used only for digital signatures and not for encryption or key distribution. |

Symmetric key systems | Asymmetric key systems |
---|---|

The same key is used for encryption and decryption. | One key is used for encryption and a different but mathematically related key is used for decryption. |

Relies on the sender and the receiver sharing a secret key. | Shared secret key exchange is not needed. |

The key must be kept secret. | One key (the secret key) must be kept secret, but the other key (the public key) is published. |

It should be computationally infeasible to derive the key or the plaintext given the algorithm and a sample of ciphertext. | It should be computationally infeasible to derive the decryption key given the algorithm, the encryption key and a sample of ciphertext. |

Faster and computationally less demanding than public key encryption. | Slower and computationally more demanding than symmetric key encryption. |

Algorithm | Description |
---|---|

MD5 | Takes any arbitrary length input string and produces a fixed 128-bit value. This is done by a method of blocking and padding and then performing four rounds of processing based on a combination of logical functions. Considered to be reasonably secure although potential weaknesses have been reported. |

SHA (secure hash algorithm) | Similar to MD5 but produces a 160-bit hash value so is more resistant to brute force attacks ^{1}. |

Discussion 2017061600