Archive For March 24, 2017

Cryptography – Asymmetric Encryption

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Cryptography – Asymmetric Encryption

we already discussed about symmetric encryption in last post, now lets look deep into asymmetric algorithm its worked based on public and private key, where is in symmetric encryption is based only on pre-shared(private keys) only .

How its works? each party will have a unique public key and private key . If A want to communicate with B, it have to encrypt his plain text with B’s public key, once its encrypted,  it can be decrypt only by B’s private key , even A cannot decrypt .

Main advantages of using Asymmetric Algorithm

  •  Key distribution is a simple process
  • Changing key is not required even ,unless private key of the receiving party is compromised.
  • communicating party can leave easily as there is no common pres-hared key .

and disadvantage is ,processing time  is relatively slow comparing to Symmetric Encryption algorithm.

Hash Function,

its a summary of the message content, and its a concept, is used to map arbitrary size of data to the fixed size,and the value got by the hash function called as hash value.

MD2,MD5, SHA are algorithms for hash function.

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Cryptography – Modern Encryption

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Modern Encryption have a common protocol all over the world, only key will kept in secret, modern cryptography divided into three categories.

  • symmetric
  • Asymmetric
  • Hash


it uses the same key for encryption and decryption, the key which is used for sharing between two parties commonly know as secret-key or pre-shared key, Main advantages of symmetric encryption its comparatively fast as both end knows same key and key-word should be more complicated if we want to have a secure encryption, Main disadvantages are as key is the only keynote for symmetric encryption transfer of key should be kept highly confidential. below are algorithm support on symmetric encryption

DES – Data Encryption Standard, its also known as data encryption algorithm, it was designed by IBM in 1976 its operating by 5 modes

  • Electric Code Book (ECB)
  • Cipher Block Chaining (CBC)
  • Cipher Feedback (CFB)
  • Output Feedback (OFB)
  • Counter Mode (CTR)

since the growth of advance technology and invention of high processer leads to DES as not secure one, it had a brute force attack , because of this issue had leads to the development of 3des

3DES – its also knows triple data encryption algorithm or TDES, it will encrypt the packet three time than DES algorithm, it was accepted by USA in 1999.

IDEA – International Data Encryption Algorithm, its also a symmetric Encryption algorithm and current one which approved and used in most the devices are AES

AES – Advanced Encryption Standard Algorithm ,its support 256 key bits ,still now this algorithm is never hacked, AES was designed to   replace DES ,3DES and IDEAS type algorithm.

AES was approved by NIST in 1997 as the replacement for DES algorithm, is more secure than DES/3DES and its fast and efficient in both hardware and software

other type of symmetric algorithms are bluefish and two fish

Stay with us for more post on encryption technology…




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Cryptography – Classical Crypotography

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Cryptography – Classical Crypotography

welcome back friends, we are discussing the concept of cryptography and its continuation and we are looking on history of cryptography. Classical cryptography is used before computer era.

caser cipher or rotation cipher

its used during the period of Julius caser. they used to rotate the character in order to confuse the enemies during communication and the receivers should know the same key to decrypt it back .

Lets takes an example of rotate by 3 ,  a become d, b become e . “hai”  the character will become “kdm” after rotation . receivers should know how to rotate it back.



Cipher disk

Cipher disk normally has two concentric disks, each with an alphabet with the periphery, two parties has to agreed with the common character set, for example “s will set d” and the character will be encrypted ,below picture show the cipher disk with we can adjust the character with inner circle “a will set to c” the character will be rotated same like caser cipher.

lot other cryptographic devices are used, during the second world war period also for secure communication. some of the devices used are mentioned below .

  • Enigma – used by Germany
  • Sigaba –  used by united states
  • Purble –  used by Japanese . after  the second world war , common laws are made for having a common encryption and concept also changed in history of encryption.

In the next post we will see the cryptography concept in Computer era.



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Data security is not full-filled without knowing cryptography concept, even if u can see in social networking software like whats app,viber you can see end to end encryption are all falls in cryptography only.

Now let us look what is cryptography, its a secret writing. Its a type of secure communication whose meaning is kept secret, crypto-analysis is the process of breaking secure communication and reading the secret message.

Below are the some of the definition,which we are going  to use in cryptographic technique. Plain text  is the term refer to readable message before applying cryptographic algorithm. chipper is the encrypted message after applying Cryptographic algorithm.

Encryption steps in cryptography :

  • Plain text –> Encryption Key–> chipper text

Decryption Steps in cryptography :

  • Chipper text –> Decryption key  –> Plain text

A good encryption will contain a strong cryptographic, which cannot be easily break it, crypto graphic concept is not a new technology, its has be rooted back to old ages its concept is used during medieval  period also. but the technology and algorithm is changed over period of time

It has been differentiated into two categories

  • Classical Cryptography
  •  Computer era cryptography

We will look on deep into above two cryptography on upcoming posts


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