Simplified view of Asymmetric Encryption, Its features, and some examples of such algorithms. This slide deck explains some of the most basics.

1. Cryptography -
Asymmetric
Encryption
5 minutes series
Abdul Manaf Vellakodath
Security Architect

2. Asymmetric Encryption - Overview
● There are many different Asymmetric
implementations around. Some of them
are:
○ Diffie-Hellman (Key Exchange)
○ RSA
○ Elliptic Curve
● RSA is the most popular commercially
used Asymmetric Algorithm from three
cryptographers:
○ Rivest
○ Shamir
● Diffie Hellman is a Key Exchange
mechanism
● RSA is also called Public Key encryption
due to its nature of keys

3. Encryption and Decryption using Asymmetric
Algorithm
Asymmetric
Key
Encryption
Algorithm
Plain
Text!
s8sdfdvsja9
qj7*jsdsf$ks
df.8sd*asfyl
dywkkeykk
Ciphertext
Decryption
Algorithm
Plain
Text!
Asymmetric
Key
< One key to encrypt and the other Key to
Decrypt>

4. RSA - Basic Premises
● The data encrypted with a Private Key can
only be decrypted with its corresponding
Public Key.
● The data encrypted with a Public Key can
only be decrypted with its corresponding
Private Key.
● The Sender has a Key called Private Key.
This key is secret. It is never transferred
out of his computer. Note: If someone
finds this key, he could impersonate the
sender.
● Everyone else, who wants to
communicate with the Sender is given a
key called the Public Key. Note: This key
is generated as part of the earlier Private
Key generation process.
● The Private and Public Keys comes in a
pair when we talk about RSA Public Key
encryption.

5. RSA Public Key Encryption - Features
● Integrity
○ Say:
■ M is the Message
■ MDh1 is the Message Digest (hash)
■ MDe is the encrypted (with the
Sender’s Private Key) form of MD
○ Send M and MDe to the Receiver.
○ Receiver will:
■ Decrypts the MDe to find the MDh1.
■ Generate MDh2 again from M.
● Confidentiality: Use the Public Key to
encrypt the message and send it to the
user. Receiver uses his Private Key
(secret) to decrypt the information, thus
passing information secretly, achieving
confidentiality.
● Non-repudiation: IF the Sender uses his
Private Key to encrypt a message, anyone
who has the respective Public Key could
decrypt his message. Since the Sender is
the only one possessing the Private Key,
only the Sender could have sent the
message. This is called non-repudiation.

6. RSA Encryption Algorithm
● Let us say:
○ Message = 65 (we want to encrypt this)
○ Public Key (n = 3233, e = 17)
○ Private Key (d = 2753)
● Encryption function:
i.e.
● Decryption function:
i.e.
Note: The encryption using the Private Key s
reversible using the Public Key. The reverse is
● Refer the following link to understand
how the RSA Keys are generated:
http://www.slideshare.net/AbdulManafV
ellakodat/cryptography-simplified-key-
generation-asymmetric-keys