Encryption-Techniques

Data Encryption Standard - DES

Usage:

Encryption

1. import DES
2. Use DES.check_msg() function on your plain text to prepare it for encryption.
3. Use DES.check_key() function on your encryption key to prepare it for further operations.
4. DES.encryption(<Key>, <Plain Text>)

msg = DES.check_msg('Your Plain Text Message')
K = DES.check_key('Your Encryption Key')

print('Encrypted Text:', end=' ')
cipher = DES.encryption(K, msg)
print(cipher)

print('Decrypted Text:', end=' ')
Message = DES.decryption(K, cipher)
print(Message)

Decryption

1. import DES
2. Use DES.check_key() function on your encryption/decryption key.
3. DES.decryption(<Key>, <Cipher Text>)

K = DES.check_key('Your Encryption Key')
print('Decrypted Text:', end=' ')
Message = DES.decryption(K, cipher)
print(Message)

RSA (Rivest-Shamir-Adleman)

RSA is an asymmetric cryptographic algorithm. Assymetric means that there are two different keys. Public and private keys refer to the ‘keys’ used to encrypt and decrypt information. A public key is available to many, and made available in an online directory. A private key is private, and only made available to the originator of the encrypted content, and those it is shared with.

Public key encryption / decryption

m stands for the plain text message and c stands for the ciphered text.

• if m < n, c = m**e mod n
• m = c**d mod n

Both sender and reciever know the value of n. The sender knows the value of e, and only the receiver knows the value of d.

PU = {e, n} PR = {d, n}

RSA Key Generation

The implementation infrastructure requires each user to have a public-private key pair where the public key is available to the world, while the private key is only known by the user.

1. choose p and q privately such that p and q are two prime numbers and p!=q
2. Calcualte n, n = p * q
3. Calculate Phi(n) privately, Phi(n) = (p-1)(q-1)
4. choose e publicly such that 1 < e < Phi(n) and Phi(n), e are relatively prime with each other i.e. gcd(Phi(n), e) = 1 and d*e mod(Phi(n))=1
5. privately calcualte d such that d = e**-1 mod(Phi(n)) and d < Phi(n)

Relatively Prime Numbers

Two integers are relatively prime if there is no integer greater than one that divides them both. In other words, they don't have any greater common divisor (GCD) other than 1.

A typical size for n is 1024-bits or 309 decimal digits less than 2**1024.

E-Signature

An electronic signature (e-signature) is a string of data that is attached to an electronic message in order to guarantee its authenticity, identify the signatory and link the content to that signatory (thereby protecting the recipient against repudiation by the sender). The e-signature provides an effective means of guaranteeing the authenticity and integrity of any document during its life and its importance. To ensure authenticity and integrity of a document, electronic signatures can be applied upon their creation.

Hash function

It is a specific function that generates a defined number of bits of hash of the original message. The hashed message is secure and unique.

Caeser Cipher

Caesar cipher (or Caesar code) is a shift cipher, one of the most easy and most famous encryption systems. It uses the substitution of a letter by another one further in the alphabet.

Usage:

Encryption

1. import Caeser
2. Caeser.encryption(<Plain Text>)

print('Encrypted Text:', end=' ')
cipher = Caeser.encryption('<Your Plain Text Message>')
print(cipher)

Decryption

1. import Caeser
2. Caeser.decryption(<Cipher Text>)

print('Decrypted Text:', end=' ')
Message = Caeser.decryption('<The encrypted cipher>')
print(Message)

Vigenere Cipher

Vigenère cipher is a method of encryption that utilizes alphabetic substitution system. The Vigenère cipher encrypts alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword.

Usage:

Encryption

1. import Vigenere
2. Vigenere.encryption(<Encryption key>, <Plain Text>)

print('Encrypted Text:', end=' ')
cipher = Vigenere.encryption('<Encryption key>', '<Your Plain Text Message>')
print(cipher)

Decryption

1. import Vigenere
2. Vigenere.decryption(<Encryption key>, <Cipher Text>)

print('Decrypted Text:', end=' ')
Message = Vigenere.decryption('<Encryption key>', '<The encrypted cipher>')
print(Message)