# Introduction To Cryptography

Cryptography ensures that vital information is hidden for unauthorized readers and is reverted to original format using decryption. It refers to science of using mathematical algorithms to store crucial information while being transmitted across insecure networks to prevent interception by unintended recipients.

Data is read and interpreted without special measures put in place referred to as plain text. Encryption is a method for disguising plain text in a format that hides its substance in unreadable gibberish namely “cipher text”.

Cryptographic science secures data, while crypt-analysis involves analysis and breaking secure communication. Classical crypt-analysis entails combination of analytical reasoning, application of mathematical implements, pattern identification, patience, determination and also luck. It can be strong or weak and the strength is measured in time and resources applied to revert back information to its original format. A strong cryptography involves cipher text which is very difficult to decipher without usage of applicable decoding tool.

Cryptographic algorithm is mathematical function used for encrypting and decrypting process in combination with a key, usually a word, number or phrase used to hide sensitive data in objects like images. The security of encrypted data depends on the strength of cryptographic algorithm and secrecy of key used. The cryptographic algorithm includes possible keys and protocols that comprises a cryptosystem for example OpenPGP.

Conventional cryptography which is also called secret key or systematic-key encryption involves one key used for both encryption and decryption. Data Encryption Standard is widely applied by federal government and the process is illustrated in the figure below:

Substitution cipher substitutes one piece of information from another mostly conducted by offsetting alphabetical letters. The most two common examples are Captain Midnight’s Secret Decoder Ring and Julius Ceaser cipher where both cases algorithm is to offset the alphabet and key which comprises of number of characters utilized to offset it.

Conventional encryption is very fast and useful for encrypting data that is not being transmitted or transferred and very expensive due to difficulty of secure key distribution. For the sender and receiver to be in synchrony, they must have common key and keep it secret among themselves. Public key cryptography is asymmetric scheme which uses pair of keys for encryption. Public key encrypts data and corresponding private/ secret key is used for decryption. The public key is published public while private key is kept a secret. Any user who has public key can encrypt data but cannot decrypt it as illustrated in the figure below:

Encryption techniques are used pervasively to protect data including personal identity, financial transactions and electronic information from unauthorized access or hackers. It strikes a balance between information apparent risks and mitigation for identified risks. Even though there are many ways to protect information from hackers and attackers which includes physical security, in today’s world there is crucial need to safeguard transmission of information over insecure networks such as internet without threat of compromise. Cryptography which is art of secret writing is employed to keep information privacy. The secret key algorithms are commonly used today are Data Encryption Standard (DES), RC4 which is stream cipher, RC5 (parameterized block cipher), Triple DES (3DES), and Advanced Encryption Standard (AES). The Secure Socket Layer applies combination of symmetric and asymmetric key algorithms and functions for digesting functions for protecting data confidentiality and integrity to and from web server.

The encryption algorithms discussed in this article are in several instances the only protection between critical information and attackers/hackers seeking to compromise them. Cryptography is indispensable tool used for protecting information in computer systems and networks if applied correctly in real world applications.