lab3 - Lab 3: Public Key Infrastructure ( (PKI) )...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
ab 3: Public Key Infrastructure Lab 3: Public Key Infrastructure (PKI) • Asymmetric cryptography VS symmetric cryptography • Digital Signature • Certificate ertification Authority (CA) Certification Authority (CA) • Secure Sockets Layer (SSL) protocol IEG 7006 (2010) 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ab 3: PKI Lab 3: PKI Asymmetric cryptography vs symmetric ptograph cryptography ymmetric cryptography Symmetric cryptography – traditional form of cryptography – a single key is used for both encryption and decryption – the sender and receiver share a key t i t h ( bli k t h ) Asymmetric cryptography (public key cryptography) – uses two mathematically related keys – a message encrypted by one key can only be decrypted by the other key – receive secure messages by simply publishing one key (the ublic key) and keeping the other secret (the private key) IEG 7006 (2010) 2 pub c ey) a d eep g t e ot e sec et (t e p vate ey)
Background image of page 2
ab 3: PKI Lab 3: PKI Asymmetric cryptography vs symmetric cryptography IEG 7006 (2010) 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lab 3: PKI RSA (Rivest-Shamir-Adelman) Implementation hoose two large primes: p and q; n=pq 1. Choose two large primes: p and q; np q 2. Choose e < n and relatively prime to (p-1)(q-1) 3. Find d such that (ed-1) is divisible by (p-1)(q-1) 4. The public key is the pair (n, e); the private key is (n, d) It is currently difficult to obtain the private key d from e public key (n e) However if one could factor n into the public key (n, e). However if one could factor n into p and q, then one could obtain the private key d. Thus the security of RSA is based on the assumption that IEG 7006 (2010) 4 factoring is difficult .
Background image of page 4
Lab 3: PKI RSA Encryption 1. Suppose A wants to send a message m to B. A creates the ciphertext c by exponentiating: c = m e mod n , where e and n are B's public key. A nds c to B sends c to B. 2. To decrypt, B also exponentiates: m = c d mod n ; e relationship between e and d ensures that B the relationship between e and d ensures that B correctly recovers m. Since only B knows d, nly B can decrypt this message only B can decrypt this message. 3. That is A is using B's public key (n, e) to
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/18/2010 for the course INFORMATIO IEG7006 taught by Professor Unknown during the Spring '10 term at CUHK.

Page1 / 19

lab3 - Lab 3: Public Key Infrastructure ( (PKI) )...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online