Data Encryption

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Data Encryption
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What is Encryption?
- The translation of data into a secret code
- To read an encrypted file, you must have access
to a secret key or password that enables you to
decrypt it
- Unencrypted data is called plain text
- encrypted data is referred to as cipher text
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Plain text
Cipher text
Dear students, My phone no. Is 24750331
Ghdu vwxghqwv, Pb skrqh qr. Lv 57083664
Encrypt
Decrypt
Dear students, My phone no. Is 24750331
Plain text
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Activity
Encrypted text
Fgct encuu yg ctg iqkpi vq vcnm cdqwv fcvc
gpetarvkqp
Original text
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Common algorithms of Encryption
Symmetric Encryption
Asymmetric Encryption
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Symmetric Encryption
A type of encryption where the same key is used
to encrypt and decrypt the message
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Symmetric Encryption (Example)
Plain text
1 0 1 1 0 1 1 0
Same Key
Encrypt
Key
1 1 0 1 1 1 1 0
XOR
Cipher text
0 1 1 0 1 0 0 1
Key
1 1 0 1 1 1 1 0
XOR
Decrypt
Plain text
1 0 1 1 0 1 1 0
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Asymmetric Encryption
Asymmetric encryption (also called public-key
encryption) involves a pair of keys - a public
and a private key.
The public key is published in a public directory
and the corresponding private key is kept secret.
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Asymmetric Encryption
The sender of the data encrypts the data with the
public key of the receiver
The data can be decrypted only with the private
key of the receiver
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Asymmetric Encryption
Plain Text
Plain Text
Cipher Text
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How to use two different keys?
One key is the inverse of the other
Public key 3, Private key 1/3 Plain text 4
Encryption cipher text public key plain
text 3
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12 Decryption plain text private key cipher
text 1/3
12 4
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Discussion
What are the uses of encryption?
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Activity
Construct a simple algorithm of encryption.