Cryptography 1 - Revision history

Adamcolton: /* Farewell */

2014-02-25T16:18:57Z

Farewell

← Older revision		Revision as of 16:18, 25 February 2014
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	==== Farewell ====		==== Farewell ====
			Don't do it yourself - use the tools.

	== Problem Sets ==		== Problem Sets ==

2014-02-25T16:13:57Z

A Unifying Theme

← Older revision		Revision as of 16:13, 25 February 2014
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	==== A Unifying Theme ====		==== A Unifying Theme ====
			A one way function maps one space to another space (possibly the same space) and evaluating f is much easier (at least one order) than inverting f.

			The existence of one-way functions relies on a proof that p=np, thus cannot be proved at this time.

	==== Farewell ====		==== Farewell ====

2014-02-25T15:19:14Z

ElGamal Variants

2014-02-24T19:54:07Z

ElGamal Security

← Older revision		Revision as of 19:54, 24 February 2014
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	==== ElGamal Security ====		==== ElGamal Security ====
			ElGamal is semantically secure.

	==== ElGamal Variants ====		==== ElGamal Variants ====
	==== A Unifying Theme ====		==== A Unifying Theme ====

2014-02-24T19:39:53Z

ElGamal System

← Older revision		Revision as of 19:39, 24 February 2014
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	=== Week 6: Public Key from Diffe-Hellman ===		=== Week 6: Public Key from Diffe-Hellman ===
	==== ElGamal System ====		==== ElGamal System ====
			Treat A,a as public, secret keys. When sending to someone, choose a new, random b, compute B, choose a random key k, encrypt m with k (producing c), encrypt k with g<sup>AB</sup> (producing ck) and send B, ck and c.

	==== ElGamal Security ====		==== ElGamal Security ====
	==== ElGamal Variants ====		==== ElGamal Variants ====

2014-02-24T19:17:42Z

RSA in Practice

← Older revision		Revision as of 19:17, 24 February 2014
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	RSA is subject to timing and power attacks. Also, a single error in encryption/decryption can expose the key.		RSA is subject to timing and power attacks. Also, a single error in encryption/decryption can expose the key.

			=== Week 6: Public Key from Diffe-Hellman ===
			==== ElGamal System ====
			==== ElGamal Security ====
			==== ElGamal Variants ====
			==== A Unifying Theme ====
			==== Farewell ====

	== Problem Sets ==		== Problem Sets ==

2014-02-24T19:14:43Z

RSA in Practice

← Older revision		Revision as of 19:14, 24 February 2014
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	==== RSA in Practice ====		==== RSA in Practice ====
			It's ok to use a small e. This makes encryption much faster than decryption.

			RSA is subject to timing and power attacks. Also, a single error in encryption/decryption can expose the key.

	== Problem Sets ==		== Problem Sets ==
	=== Week 2 ===		=== Week 2 ===

2014-02-24T15:38:36Z

Is RSA One Way

← Older revision		Revision as of 15:38, 24 February 2014
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	==== Is RSA One Way ====		==== Is RSA One Way ====
			Very mathy.

			Given that RSA decryption is
			c<sup>d</sup> = m (mod N)
			Using a small d would speed up decryption. But if d < N<sup>0.292</sup> then RSA is insecure. By insecure, we can recover the private key. Also, it is conjectured that this actually holds true up to N<sup>0.5</sup>

	==== RSA in Practice ====		==== RSA in Practice ====
	== Problem Sets ==		== Problem Sets ==

2014-02-24T15:12:21Z

PKCS 1

← Older revision		Revision as of 15:12, 24 February 2014
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	==== PKCS 1 ====		==== PKCS 1 ====
			Public Key Cryptography Standard 1

			Mode 2: 16 bits to id PKCS1M2, random pad that does not contain FF, FF (as a separator) then the message. But the leading 16 bit can be used as an oracle to break the system.

			Version 2.0: OAEP optimal asymmetric encryption padding. Takes the message and a random value. Concat the message (symmetric key) with a hash f the message and the random value. Take that and XOR it against the hash of r. Finally take that concat with r and apply RSA.

	==== Is RSA One Way ====		==== Is RSA One Way ====
	==== RSA in Practice ====		==== RSA in Practice ====

2014-02-19T15:57:15Z

RSA Trapdoor Permutation

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 ==== RSA Trapdoor Permutation ====
 ==== PKCS 1 ====
 ==== Is RSA One Way ====