1. CRYPTOGRAPHY Cryptography is art or science of transforming intelligible message to unintelligible and again transforming that message back to the original form

2. TERMINOLOGIES -Encryption(Enciphering) :Process of encoding the message so that meaning is not obvious or not in understandable form -Decryption(Deciphering): Reverse process of encryption -Plaintext: The original form of the message - Cipher text: Disguised(encrypted) message

3. Key : Critical (secret) information used in cipher and known only to sender and receiver Symmetric – Shared key Asymmetric – Public key Code: Algorithm used for transforming the intelligible (plain text) to unintelligible (cipher text) Cipher: Is algorithm /Code used for transforming plaintext to cipher text Cryptanalysis (Code breaking): Study of method for transforming cipher text to plaintext without having knowledge of any key Cryptology : Area of cryptography and cryptanalysis together is called as cryptology

4. OBJECTIVES Availability : Ensures the availability of desired resource Confidentiality : only sender and receiver can understand the message Integrity: Sender and receiver may have provision to check the integrity of data & get themselves ensured that message is not altered Anonymity : Ensures the privacy of the origin of data Authenticity : Sender or receiver want to confirm the identity of each other and may be possible they would access some service after giving there authentication Authorization: Access to the resources are authorized

5. TWO TYPES OF ENCRYPTION TWO TYPES OF ENCRYPTION SYMMETRIC - Symmetric key cryptography Is also termed as private or secret key encryption because secret key is shared between sender and receiver ASYMMETRIC- Two keys are involved in asymmetric encryption. One key is used by sender to encrypt the data and other by receiver to decrypt the data

6. Cryptographic Techniques All cryptographic algorithms are based on following two techniques- Substitution, Transposition (Permutation) Substitution Technique: Is one in which the letters of the plaintext are replaced by other letters (i.e. Fixed symbols or alphabets) Transposition Technique: Method of disguising text or alphabet by shuffling or exchanging their position

7. PUBLIC KEY CRYPTOGRAPHY Asymmetric key cryptography. Two keys Public, Private. PUBLIC key is used by the sender. PRIVATE key is available to the reciever only. Both the keys are related based on complex mathematical formulas. There needs to be some methods for transferring PUBLIC keys. Example- X.509 Digital Certificates.

8. DIGITAL CERTIFICATES DIGITAL CERTIFICATES Intended for AUTHENTICATION purpose. A certificate is a file of information that identifies a user and its details like organisation name, organisation issuing the certificate, email address. Certificate is send as a reply when the client /server sends a query to start a connection. The other party’s public key can be extracted. To create it a PUBLIC KEY INFRASTRUCTURE (PKI) is required.

9. PKI PKI It is a framework that consists of hardware;software;policies that exist to manage, create, store, and distribute keys IMPORTANT PARTS OF PKI  Digital certificates  Certificate authorities  Certificate generation and destruction  Key management

10. CRYPTOGRAPHIC ALGORITHMS CRYPTOGRAPHIC ALGORITHMS MD5 (Message Digest 5) SHA (Secure Hash Algorithm) RC4 RC5 MAC (Message authentication Code) HMAC