Sunday, 20 November 2011


Cryptography and steganography

  • Sunday, 20 November 2011
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  • irst of all start with the difference between these two. In simple words cryptography is a process of securing a message so that message is visible to everyone but no one can read it without authorized key and steganography is the process of hiding a message such that no one can see the message but once if message is found then anyone can read it without any key or password. So lets start with introduction of the above mentioned two terms.

    Basically cryptography is a technique to communicate securely between two person in presence of third party without their interference. More generally it is constructing protocols that overcome the influence of adversaries and which are related to various aspects such as data confidentiality, data integrity and authenticity. Application of cryptography includes ATM cards, password etc. key is needed to perform cryptography, this key is used as a password to encrypt and decrypt.
    Cryptography is based on encryption and decryption of data. Encryption basically means converting simple text form into unintelligible form. Simple form of data is referred as plain textand encrypted data is called cipher/cypher text. Whereas converting cipher text into plain text is termed as decryption. An authorized rypt data. sender uses his key to encrypt data and reciever use the key to read the message.

    -Modern cryptography:

    Symmetric key cryptography-
    It refers to the type of cryptography in which sender and receiver both uses same key. Symmetric key ciphers are implemented as either block cipher or stream cipher. A block cipher enciphers input in blocks of plaintext as opposed to individual characters, the input form used by a stream cipher. The Data Encryption Standard (DES) and the Advance Encryption standard (AES) are block cipher designs which have been designated cryptography standards by the US government (though DES's designation was finally withdrawn after the AES was adopted). Despite its deprecation as an official standard, DES (especially its still-approved and much more secure triple- DES variant) remains quite popular; it is used across a wide range of applications, from ATM encryption to e-mail privacy and secure remote access.
    Stream ciphers, in contrast to the 'block' type, create an arbitrarily long stream of key material, which is combined with the plaintext bit-by-bit or character-by-character, somewhat like the one time pad. In a stream cipher, the output stream is created based on a hidden internal state which changes as the cipher operates.

    Public Key cryptography-
    Symmetric-key cryptosystems use the same key for encryption and decryption of a message, though a message or group of messages may have a different key than others. A significant disadvantage of symmetric ciphers is the key management necessary to use them securely. Each distinct pair of communicating parties must, ideally, share a different key, and perhaps each ciphertext exchanged as well. The number of keys required increases as the square of the number of network members, which very quickly requires complex key management schemes to keep them all straight and secret. The difficulty of securely establishing a secret key between two communicating parties, when a secure channel does not already exist between them.

    Tools for cryptography:
    These are few good tools for cryptography. In my opinion trueCrypt is best among all. Here is the video tutorial for TryeCrypt:

    Steganography is the art and science of writing hidden message in such a way that no one can judge the presence of a message. Normally a file will look like an image or a song or a simple text file but in fact a special message is hidden below it. Hiding of such messages is the art of steganography. Advantage of steganography over cryptography is that these messages don't attract people to themselves. Every message is hack-able, doesn't matter how secure it is, so cryptographed message can be hacked but stagenographed message is better because no one knows that there is a message.

    Tools for steganography:
    1.Pict Encrypt(Mac)
    2.Hide i picntures
    3.S-Tools 4.0
    Normaly anyone can use tools for doing steganography but here i am teaching you a simple cmd prompt trick by which you can hide your secret message in some image or any document.
    go to command prompt and type 
    copy \B original.jpg+hidden.txt new.jpg (press enter)
    [original is a image in which you want to hide your message and hidden is a text message which you want to hide]
    Now when you will normally open new.jpg it will show you the image but when you open new.jpg in notepad you can read your message. 

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    1 Responses to “ Cryptography and steganography ”

    Amber Salm said...
    3 July 2013 at 20:39

    I was searching around for some good detail about cryptography process. From your blog post I have learn a new security process which appears to be similar like cryptography but is totally different from technical viewpoint.
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