BASICS OF "CRYPTOGRAPHY"
CRYPTOGRAPHY
- What is cryptography?
- Classification of cryptography?
- How various cryptographic algorithms work?
1. WHAT IS CRYPTOGRAPHY?
as you see in the picture first we write a word or paragraph, or the thing we need to encrypt .
and then the software make 2 keys 1) Receiver's key public key
2) Private key
sender sends the message of form public key and
the receiver uses the Private key to unencrypt the message of the sender .
(As the hackers and normal users only see a useless message and cant unencrypt it .But the owner of private key can see the real text or message .)
2. CLASSIFICATION OF CRYPTOGRAPHY.
- Symmetric key cryptography:
An encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message. The most popular symmetric-key system is the Data Encryption Standard (DES)
- Transposition cipher:
In Cryptography a transposition cipher is a method of encryption by which the positions held by units of plain text (which are commonly characters or groups of characters) are shifted according to a regular system, so that the ciphertext constitutes a permutation of plan text
- Substitution cipher:
Method of encrypting by which units of plaintext are replaced with cipher text, according to a fixed system; the "Units" may be single letters
(the most common) pair's of letters ,triplets of letters ,mixture of above and forth.
- Stream cipher:
A symmetric or secret-key encryption algorithm that encrypts a single bit at a time. with a stream cipher ,the same plaintext bit or byte will encrypts to a different bit or byte every time it is encrypted.
- Block cipher:
An encryption method that applies a deterministic algorithm along with a symmetric key to encrypt a block of text, rather than encrypting on a bit at a time as in stream cipher's.
as you see in the picture first we write a word or paragraph, or the thing we need to encrypt .
and then the software make 2 keys 1) Receiver's key public key
2) Private key
sender sends the message of form public key and
the receiver uses the Private key to unencrypt the message of the sender .
(As the hackers and normal users only see a useless message and cant unencrypt it .But the owner of private key can see the real text or message .)
2. CLASSIFICATION OF CRYPTOGRAPHY.
- Symmetric key cryptography:
An encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message. The most popular symmetric-key system is the Data Encryption Standard (DES)
- Transposition cipher:
In Cryptography a transposition cipher is a method of encryption by which the positions held by units of plain text (which are commonly characters or groups of characters) are shifted according to a regular system, so that the ciphertext constitutes a permutation of plan text
- Substitution cipher:
Method of encrypting by which units of plaintext are replaced with cipher text, according to a fixed system; the "Units" may be single letters
(the most common) pair's of letters ,triplets of letters ,mixture of above and forth.
- Stream cipher:
A symmetric or secret-key encryption algorithm that encrypts a single bit at a time. with a stream cipher ,the same plaintext bit or byte will encrypts to a different bit or byte every time it is encrypted.
- Block cipher:
An encryption method that applies a deterministic algorithm along with a symmetric key to encrypt a block of text, rather than encrypting on a bit at a time as in stream cipher's.
In Cryptography a transposition cipher is a method of encryption by which the positions held by units of plain text (which are commonly characters or groups of characters) are shifted according to a regular system, so that the ciphertext constitutes a permutation of plan text
- Substitution cipher:
Method of encrypting by which units of plaintext are replaced with cipher text, according to a fixed system; the "Units" may be single letters
(the most common) pair's of letters ,triplets of letters ,mixture of above and forth.
- Stream cipher:
A symmetric or secret-key encryption algorithm that encrypts a single bit at a time. with a stream cipher ,the same plaintext bit or byte will encrypts to a different bit or byte every time it is encrypted.
- Block cipher:
An encryption method that applies a deterministic algorithm along with a symmetric key to encrypt a block of text, rather than encrypting on a bit at a time as in stream cipher's.
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