Encryption Algorithms - Revision history

Anweiss: /* Modes of Operation */

2005-02-08T09:45:06Z

Modes of Operation

← Older revision		Revision as of 09:45, 8 February 2005
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	Even more important than the algorithm itself is the mode you are using it.		Even more important than the algorithm itself is the mode you are using it.

			===== ECB =====
	If everything is done like shown above the mode is called Electronic Code Book or ECB.		If everything is done like shown above the mode is called Electronic Code Book or ECB.

			===== CBC =====
	If you XOR the previous block of cipher text with the current block of plaintext, before you encrypt the message, the mode is called Cipher Block Chaining (CBC)		If you XOR the previous block of cipher text with the current block of plaintext, before you encrypt the message, the mode is called Cipher Block Chaining (CBC)

			===== CFB =====
	The CBC is also used for the Cipher Feedback (CFB) mode.		The CBC is also used for the Cipher Feedback (CFB) mode.
	First the message is encrypted using CBC mode but when everything is computed we just throw away everything but the last block. As you can see the last block depends on all the other blocks before it, so it can be used as message authentification code (MAC).		First the message is encrypted using CBC mode but when everything is computed we just throw away everything but the last block. As you can see the last block depends on all the other blocks before it, so it can be used as message authentification code (MAC).
	Then this last block is added to the end of the message and everything is encrypted again with CBC and a second key.		Then this last block is added to the end of the message and everything is encrypted again with CBC and a second key.
	This way the receiver of the message is able to check if the message was altered.		This way the receiver of the message is able to check if the message was altered.


	==== Types of DES ====		==== Types of DES ====

Anweiss: /* DES a symmetric encryption algorithm */

2005-02-08T09:43:37Z

DES a symmetric encryption algorithm

← Older revision		Revision as of 09:43, 8 February 2005
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	The original algorithm ''Lucifer'' was implemented in the early 1970’s by IBM and was verified and altered by the NSA, after the National Bureau of Standards (NBS), pointed out the need of a standard encryption algorithm.		The original algorithm ''Lucifer'' was implemented in the early 1970’s by IBM and was verified and altered by the NSA, after the National Bureau of Standards (NBS), pointed out the need of a standard encryption algorithm.

	DES stands for Data Encryption ~~Standart~~.		DES stands for Data Encryption Standard.

	==== Preparation ====		==== Preparation ====

Anweiss: /* DES a symmetric encryption algorithm */

2005-02-08T09:43:23Z

DES a symmetric encryption algorithm

← Older revision		Revision as of 09:43, 8 February 2005
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	=== DES a symmetric encryption algorithm ===		=== DES a symmetric encryption algorithm ===
	The original algorithm ''Lucifer'' was implemented in the early 1970’s by IBM and was verified and altered by the NSA, after the National Bureau of Standards (NBS), pointed out the need of a standard encryption algorithm.		The original algorithm ''Lucifer'' was implemented in the early 1970’s by IBM and was verified and altered by the NSA, after the National Bureau of Standards (NBS), pointed out the need of a standard encryption algorithm.

			DES stands for Data Encryption Standart.

	==== Preparation ====		==== Preparation ====

Anweiss: /* DES a symmetric encryption algorithm */

2005-02-08T09:42:28Z

DES a symmetric encryption algorithm

← Older revision		Revision as of 09:42, 8 February 2005
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	=== DES a symmetric encryption algorithm ===		=== DES a symmetric encryption algorithm ===
	The original algorithm Lucifer was implemented in the early 1970’s by IBM, ~~but it~~ was verified and altered by the NSA.		The original algorithm ''Lucifer'' was implemented in the early 1970’s by IBM and was verified and altered by the NSA, after the National Bureau of Standards (NBS), pointed out the need of a standard encryption algorithm.

	==== Preparation ====		==== Preparation ====
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	This type was necessary as it expands the effective encryption strength from 2 to the power 56 to 2 to the power 112. In 1999 it took about 2 days to encrypt a DES encrypted message by brute force, but from today’s view our sun will become a supernova before 3DES can be decrypted by brute force.		This type was necessary as it expands the effective encryption strength from 2 to the power 56 to 2 to the power 112. In 1999 it took about 2 days to encrypt a DES encrypted message by brute force, but from today’s view our sun will become a supernova before 3DES can be decrypted by brute force.


	== Asymmetric Cryptography ==		== Asymmetric Cryptography ==

Anweiss: /* What is it? */

2005-02-08T09:12:52Z

What is it?

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	== Symmetric Cryptography ==		== Symmetric Cryptography ==
	=== What is it?===		=== What is it?===
			The basic thing about symmetric encryption is that the same key is used for both encryption and decryption.
	under construction...

			If Alice wants to send a message to Bob, she writes the message and puts it in a safe.
			She locks the save using a special key.
			She gives this key to Bob and he can open the safe with this key and read the message.

	=== DES a symmetric encryption algorithm ===		=== DES a symmetric encryption algorithm ===
	The original algorithm Lucifer was implemented in the early 1970’s by IBM, but it was verified and altered by the NSA.		The original algorithm Lucifer was implemented in the early 1970’s by IBM, but it was verified and altered by the NSA.

Anweiss: /* Preparation */

2005-02-08T09:07:36Z

Preparation

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	63 55 47 39 31 23 15		63 55 47 39 31 23 15
	7 62 54 46 38 30 22		7 62 54 46 38 30 22
	14 6 61 53 45 37 29		14 6 61 53 45 37 29
	21 13 5 28 20 12 4		21 13 5 28 20 12 4

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	As the result we get 16 Sub keys, where each sub key has a length of 48 bit.		As the result we get 16 Sub keys, where each sub key has a length of 48 bit.


	==== Encryption ====		==== Encryption ====

Anweiss at 09:06, 8 February 2005

2005-02-08T09:06:31Z

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 The original algorithm Lucifer was implemented in the early 1970’s by IBM, but it was verified and altered by the NSA.
-==== Encryption ====
+==== Preparation ====
 To encode a message we first rearrange every 64bit block of it according to table IP

Anweiss at 08:57, 8 February 2005

2005-02-08T08:57:31Z

← Older revision		Revision as of 08:57, 8 February 2005
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	S1		S1
	0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15		0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
	0 14 4 13 1 2 15 11 8 3 10 6 12 5 9 0 7		0 14 4 13 1 2 15 11 8 3 10 6 12 5 9 0 7
	1 0 15 7 4 14 2 13 1 10 6 12 11 9 5 3 8		1 0 15 7 4 14 2 13 1 10 6 12 11 9 5 3 8
	2 4 1 14 8 13 6 2 11 15 12 9 7 3 10 5 0		2 4 1 14 8 13 6 2 11 15 12 9 7 3 10 5 0
	3 15 12 8 2 4 9 1 7 5 11 3 14 10 0 6 13		3 15 12 8 2 4 9 1 7 5 11 3 14 10 0 6 13

	Every B has its own S-Box.		Every B has its own S-Box.
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	P (4bit * 8 = 32bit)		P (4bit * 8 = 32bit)

	16 7 20 2		16 7 20 2
	29 12 28 17		29 12 28 17

Anweiss at 08:56, 8 February 2005

2005-02-08T08:56:56Z

← Older revision		Revision as of 08:56, 8 February 2005
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	P (4bit * 8 = 32bit)		P (4bit * 8 = 32bit)

	16 7 20 2		16 7 20 2
	29 12 28 17		29 12 28 17
	1 15 23 26		1 15 23 26
	5 18 31 10		5 18 31 10
	2 8 24 14		2 8 24 14
	32 27 3 9		32 27 3 9
	19 13 30 6		19 13 30 6
	22 11 4 25		22 11 4 25

	When we have finished this for all 16 L’s and R’s we apply the final permutation according to table IP-1.		When we have finished this for all 16 L’s and R’s we apply the final permutation according to table IP-1.

	IP-1		IP-1
	40 8 48 16 56 24 64 32		40 8 48 16 56 24 64 32
	39 7 47 15 55 23 63 31		39 7 47 15 55 23 63 31
	38 6 46 14 54 22 62 30		38 6 46 14 54 22 62 30
	37 5 45 13 53 21 61 29		37 5 45 13 53 21 61 29
	36 4 44 12 52 20 60 28		36 4 44 12 52 20 60 28
	35 3 43 11 51 19 59 27		35 3 43 11 51 19 59 27
	34 2 42 10 50 18 58 26		34 2 42 10 50 18 58 26
	33 1 41 9 49 17 57 25		33 1 41 9 49 17 57 25


	This output is the encrypted 64bit block of message.		This output is the encrypted 64bit block of message.

Anweiss at 08:56, 8 February 2005

2005-02-08T08:56:13Z

@@ Line 1: / Line 1: @@
 == Symmetric Cryptography ==
 === What is it?===
 === DES a symmetric encryption algorithm ===
 The original algorithm Lucifer was implemented in the early 1970’s by IBM, but it was verified and altered by the NSA.
 == Asymmetric Cryptography ==