Diffie-Hellman is an asymmetric cipher defined in U.S. Patent 4,200,770 in 1977, the same year that IBM’s algorithm was selected as the Data Encryption Standard. The Diffie-Hellman patent expired on 6 September, 1997. The Diffie-Hellman algorithm is named after its creators: Whitfield Diffie and Martin Hellman. ElGamal is a variant of Diffie-Hellman which was invented by Taher Elgamal.      

A wordlist is a text file containing a collection of words for use in a dictionary attack. Wordlist Usage A dictionary attack using a wordlist relies on the fact that most users choose weak passwords. Very common passwords include password, computer, work, and most of the popular female names. Common Dictionary Attacks Using A Wordlist The most common uses for wordlists are auditing windows passwords and Unix passwords. It is also possible to use a wordlist to recover passwords on documents and files, such as Zip passwords. In fact, a Read More

In the most basic of descriptions, quantum cryptography is any set of cryptographic tasks that are done by quantum systems. The most famous of these systems is known as quantum key distribution (QKD). By using quantum mechanics, the crytograph can ensure a secure communication. Because of the randomness, it allows for the two parties to generate a bit string that they – being the ones that know it – can then use to encrypt or decrypt messages. Because quantum cryptography is dealing with quantum, the two parties that are using Read More

GPG, or GnuPG, is GNU Privacy Guard. GnuPG is a complete and free replacement for PGP. Gpg4win is an installer package for GPG that adds a graphical shell and plugins for Microsoft Outlook and Windows Explorer. Because GPG does not use the patented IDEA algorithm, it can be used without any restrictions. GnuPG is a RFC2440 (OpenPGP Message Format) compliant application. GPG Encryption Protocol Support GnuPG supports the ElGamal, DSA, RSA, AES, 3DES, Blowfish, Twofish, CAST5, MD5, SHA-1, RIPE-MD-160 and TIGER algorithms. Additional Reading on GPG For more information on Read More

XOR is known as ‘Exclusive-OR’ and it is a Boolean operator that returns a TRUE when only one of the operands is TRUE and returns a FALSE when both of the operands are either TRUE or FALSE. It is a logical operation on two logical values. Going by the rules of material implication and material equivalence, the exclusive-or is equivalent to the negation of the logical bi-conditional. Properties XOR is an associative operation i.e. re-arranging the parenthesis in an expression having two or more same associative operators in a row Read More

SHA stands for Secure Hash Algorithm. It consists of five hash functions designed by the National Security Agency (NSA) and published by the National Institute of Standards and Technology (NIST). The five algorithms are SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512. SHA-1 is the most commonly used of the SHA series. Hash algorithms are called secure when It is impossible to find a message that corresponds to a given message digest. It is impossible to find two different messages that produce the same message digest. If a message is changed even Read More

In a symmetric cipher, both parties must use the same key for encryption and decryption. This means that the encryption key must be shared between the two parties before any messages can be decrypted. Symmetric systems are also known as shared secret systems or private key systems. Symmetric ciphers are significantly faster than asymmetric ciphers, but the requirements for key exchange make them difficult to use. In an asymmetric cipher, the encryption key and the decryption keys are separate. In an asymmetric system, each person has two keys. One key, Read More

PGP (Pretty Good Privacy) is a data encryption and decryption program used in e-mail messaging, encrypting/decrypting texts, files, or even disk partitions, in order to provide security of data. The program was created in 1991, by Phil Zimmerman. Pretty Good Privacy encryption is based on using a serial combination of data compression, hashing, public-key cryptography and symmetric-key cryptography. Public keys are bound to e-mail addresses or usernames. How Does PGP Work? PGP is used for sending messages confidentially. It combines public-key and symmetric-key encryption. A symmetric encryption algorithm is used Read More

The XOR encryption is a simple symmetric cipher that is used in many applications where security is not a defined requirement. The XOR Operator XOR (Exclusive OR) is a bitwise operator from binary mathematics. The six bitwise operators, as defined in the C programming language, are: Operation Symbol AND & Inclusive OR | Exclusive OR (XOR) ^ Right Shift >> Left Shift << Complement ~ The XOR operator returns a 1 when the value of either the first bit or the second bit is a 1. The XOR operator returns Read More

A one-time pad is the only theoretically unbreakable cipher. A one-time pad is a private key, or symmetric, cipher where the key size is equal to the plaintext size. Because of this, the key is never reutilized. As the key is never reutilized, there is no basis for mathematical cryptanalysis. An example of a very poor one-time pad would be if you were to encrypt a letter to a friend using a substitution cipher and using Hemingway’s A Farewell to Arms as a key. Your friend could decrypt your letter Read More