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© 2006 Cisco Systems, Inc. All rights reserved. Network Security 2 Module 3: VPN and Encryption Technology.

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Presentation on theme: "© 2006 Cisco Systems, Inc. All rights reserved. Network Security 2 Module 3: VPN and Encryption Technology."— Presentation transcript:

1 © 2006 Cisco Systems, Inc. All rights reserved. Network Security 2 Module 3: VPN and Encryption Technology

2 © 2006 Cisco Systems, Inc. All rights reserved. Lesson 3.1 Encryption Basics Module 3: VPN and Encryption Technology

3 © 2006 Cisco Systems, Inc. All rights reserved. Symmetrical encryption

4 © 2006 Cisco Systems, Inc. All rights reserved. Symmetrical encryption  Used for large volumes of data  Encryption algorithms available in the IOS Digital Encryption Standard (DES) Triple DES (3DES) Advanced Encryption Standard (AES)  The most important feature of a cryptographic algorithm is its security against being compromised.  Symmetric encryption algorithms are built so that it is extremely difficult for anyone to determine the clear text without having this key.

5 © 2006 Cisco Systems, Inc. All rights reserved. Symmetrical encryption  DES is the most widely used symmetric encryption scheme today. 64-bit message blocks  3DES is an alternative to DES Preserves the existing investment in software Makes a brute- force attack more difficult. Takes a 64-bit block of data and performs the operations of encrypt, decrypt, and encrypt. US Government restricts export of 3DES technology  AES is a newer encryption algorithm. Specifies keys with a length of 128, 192, or 256 bits Nine combinations of key length and block length are possible.

6 © 2006 Cisco Systems, Inc. All rights reserved. Asymmetric Encryption

7 © 2006 Cisco Systems, Inc. All rights reserved. Asymmetric Encryption  AKA public key encryption  Can use either the same or different but complementary algorithms to scramble and unscramble data.  The required public key and a private key are different, but related. Key pairs generation are complex, result in two very large random numbers. Processor intensive.  Rarely used for data confidentiality because of performance constraints.  Used in applications involving authentication using digital signatures and key management.  Common public key algorithms are the Rivest-Shamir-Adleman (RSA) algorithm and the El Gamal algorithm.

8 © 2006 Cisco Systems, Inc. All rights reserved. Asymmetric Encryption – RSA Encryption

9 © 2006 Cisco Systems, Inc. All rights reserved. Asymmetric Encryption – RSA Encryption  For RSA there are two methods RSA signatures and RSA encryption.  RSA encryption generates a value known as a nonce. Nonce is temporary random string, combined with the peer public key. Requires more processing power and decreases throughput  An RSA signature is the method that uses digital certificates. Very scalable and used by medium and large corporations.  Non-repudiation is the ability to prove a transaction occurred, RSA signatures provide non-repudiation. RSA encryption does not provide non-repudiation.

10 © 2006 Cisco Systems, Inc. All rights reserved. DH Key Exchange Merchant Bank Public Key A + Private Key B Shared Secret Key (BA) Credit Card Charge $100.00 Public Key B + Private Key A Shared Secret Key (AB) = 4ehIDx67NMop9eR U78IOPotVBn45TR 4ehIDx67NMop9eR U78IOPotVBn45TR Key Decrypt Encrypt Internet

11 © 2006 Cisco Systems, Inc. All rights reserved. Lesson 3.2 Integrity Basics Module 3: VPN and Encryption Technology

12 © 2006 Cisco Systems, Inc. All rights reserved. Hashing

13 © 2006 Cisco Systems, Inc. All rights reserved. Hashing Two common hashing algorithms are Message Digest (MD) and Secure Hash Algorithm (SHA)

14 © 2006 Cisco Systems, Inc. All rights reserved. Hashed Method Authentication Code (HMAC)

15 © 2006 Cisco Systems, Inc. All rights reserved. Hashed Method Authentication Code (HMAC)  HMAC combines shared secret key with the message. A hash algorithm is a formula used to develop a fixed-length string of digits that is unique to the contents of the message.

16 © 2006 Cisco Systems, Inc. All rights reserved. Digital signatures and certificates

17 © 2006 Cisco Systems, Inc. All rights reserved. Digital signatures and certificates

18 © 2006 Cisco Systems, Inc. All rights reserved. Digital signatures and certificates

19 © 2006 Cisco Systems, Inc. All rights reserved. Q and A

20 © 2006 Cisco Systems, Inc. All rights reserved.

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