This document discusses secure hashing algorithms used for authentication rather than encryption. It provides an overview of the requirements for authentication including preventing masquerading, content modification, sequence modification, and timing modification. It then describes the basic theory behind hashing including producing a message digest, ensuring it is computationally infeasible to find two messages with the same digest, and being unable to recreate a message from its digest. Finally, it details the framework of the SHA-1 hashing algorithm including preprocessing the message, initializing buffers, processing the message in blocks, and outputting the final digest.
Security Hash Algorithm (SHA) was developed in 1993 by the National Institute of Standards and Technology (NIST) and National Security Agency (NSA).
It was designed as the algorithm to be used for secure hashing in the US Digital Signature Standard.
• Hashing function is one of the most commonly used encryption methods. A hash is a special mathematical function that performs one-way encryption.
• SHA-l is a revised version of SHA designed by NIST and was published as a Federal Information Processing Standard (FIPS).
• Like MD5, SHA-l processes input data in 512-bit blocks.
• SHA-l generates a 160-bit message digest. Whereas MD5 generated message digest of 128 bits.
• The procedure is used to send a non secret but signed message from sender to receiver. In such a case following steps are followed:
1. Sender feeds a plaintext message into SHA-l algorithm and obtains a 160-bit SHA-l hash.
2. Sender then signs the hash with his RSA private key and sends both the plaintext message and the signed hash to the receiver.
3. After receiving the message, the receiver computes the SHA-l hash himself and also applies the sender's public key to the signed hash to obtain the original hash H.
Security Hash Algorithm (SHA) was developed in 1993 by the National Institute of Standards and Technology (NIST) and National Security Agency (NSA).
It was designed as the algorithm to be used for secure hashing in the US Digital Signature Standard.
• Hashing function is one of the most commonly used encryption methods. A hash is a special mathematical function that performs one-way encryption.
• SHA-l is a revised version of SHA designed by NIST and was published as a Federal Information Processing Standard (FIPS).
• Like MD5, SHA-l processes input data in 512-bit blocks.
• SHA-l generates a 160-bit message digest. Whereas MD5 generated message digest of 128 bits.
• The procedure is used to send a non secret but signed message from sender to receiver. In such a case following steps are followed:
1. Sender feeds a plaintext message into SHA-l algorithm and obtains a 160-bit SHA-l hash.
2. Sender then signs the hash with his RSA private key and sends both the plaintext message and the signed hash to the receiver.
3. After receiving the message, the receiver computes the SHA-l hash himself and also applies the sender's public key to the signed hash to obtain the original hash H.
this presentation is on block cipher modes which are used for encryption and decryption to any message.That are Defined by the National Institute of Standards and Technology . Block cipher modes of operation are part of symmetric key encryption algorithm.
i hope you may like this.
SHA - 256 Algorithm is an concept of Block Chain Technology . It is an Hashing method, Hashing is the process of scrambling raw information to the extent that it cannot reproduce it back to its original form. SHA-256 is a part of the SHA 2 family of algorithms, where SHA stands for Secure Hash Algorithm. Published in 2001. It's applications include hash tables, integrity verification, challenge handshake authentication, digital signatures, etc.I have also given an complete solved example of this algorithm.
this is about international data encryption algorithm. this is first ever ppt which includes its history, encryption , figure, decryption and application.. do share ur views after viewing it if u like..
this presentation is on block cipher modes which are used for encryption and decryption to any message.That are Defined by the National Institute of Standards and Technology . Block cipher modes of operation are part of symmetric key encryption algorithm.
i hope you may like this.
SHA - 256 Algorithm is an concept of Block Chain Technology . It is an Hashing method, Hashing is the process of scrambling raw information to the extent that it cannot reproduce it back to its original form. SHA-256 is a part of the SHA 2 family of algorithms, where SHA stands for Secure Hash Algorithm. Published in 2001. It's applications include hash tables, integrity verification, challenge handshake authentication, digital signatures, etc.I have also given an complete solved example of this algorithm.
this is about international data encryption algorithm. this is first ever ppt which includes its history, encryption , figure, decryption and application.. do share ur views after viewing it if u like..
This presentation has information about what do you mean by an algorithm, what is hashing and various hashing algorithms and their applications. Approximate counting Algorithm and their applications, Counting Distinct Elements Algorithm and their applications and Frequency estimation algorithm and their applications . Also, the research papers we referenced.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
How to Create Map Views in the Odoo 17 ERPCeline George
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How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
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The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
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Ethnobotany and Ethnopharmacology:
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This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
2. Purpose: Authentication
Not Encryption
Authentication Requirements:
Masquerade – Insertion of message from
fraudulent source
Content Modification – Changing content of
message
Sequence Modification – Insertion, deletion
and reordering sequence
Timing Modification – Replaying valid
sessions
3. Background Theory
• Message Digest or “Fingerprint”
→ Condensed Representation
→ Easy to generate for a given file.
• Computationally infeasible to produce two
messages with same message digest
• Impossible to recreate a message given a
message digest.
• Data Integrity and Comparison Checking
→ Message Integrity Validation
4. Applications:
One-way hash functions
• Public Key Algorithms
– Password Logins
– Encryption Key Management
– Digital Signatures
• Integrity Checking
– Virus and Malware Scanning
• Authentication
– Secure Web Connections
• (PGP, SSL, SSH, S/MIME)
5. Variants
• MD4 and MD5 by Ron Rivest (1990,1994)
• SHA-0, SHA-1 by NSA (1993, 1995)
• RIPEMD-160 (1996)
• SHA-2 (2002 – 224, 256, 385, 512)
• Whirlpool
• Tiger
• GOST-3411
• SHA-3
• Winner selected from solicitations in 2012
8. SHA-1 (160 bit message)
Algorithm Framework
Step 1: Append Padding Bits….
Message is “padded” with a 1 and as many 0’s as
necessary to bring the message length to 64 bits fewer
than an even multiple of 512.
Step 2: Append Length....
64 bits are appended to the end of the padded message. These bits
hold the binary format of 64 bits indicating the length of the original
message.
http://www.herongyang.com
f
9. SHA-1 Framework Continued
Step 3: Prepare Processing Functions….
SHA1 requires 80 processing functions defined as:
f(t;B,C,D) = (B AND C) OR ((NOT B) AND D) ( 0 <= t <= 19)
f(t;B,C,D) = B XOR C XOR D (20 <= t <= 39)
f(t;B,C,D) = (B AND C) OR (B AND D) OR (C AND D) (40 <= t <=59)
f(t;B,C,D) = B XOR C XOR D (60 <= t <= 79)
Step 4: Prepare Processing Constants....
SHA1 requires 80 processing constant words defined as:
K(t) = 0x5A827999 ( 0 <= t <= 19)
K(t) = 0x6ED9EBA1 (20 <= t <= 39)
K(t) = 0x8F1BBCDC (40 <= t <= 59)
K(t) = 0xCA62C1D6 (60 <= t <= 79)
http://www.herongyang.com
10. SHA-1 Framework Continued
Step 5: Initialize Buffers….
SHA1 requires 160 bits or 5 buffers of words (32 bits):
H0 = 0x67452301
H1 = 0xEFCDAB89
H2 = 0x98BADCFE
H3 = 0x10325476
H4 = 0xC3D2E1F0
http://www.herongyang.com
11. SHA-1 Framework Final Step
Step 6: Processing Message in 512-bit
blocks (L blocks in total message)….
This is the main task of SHA1 algorithm which loops through the
padded and appended message in 512-bit blocks.
Input and predefined functions:
M[1, 2, ..., L]: Blocks of the padded and appended message
f(0;B,C,D), f(1,B,C,D), ..., f(79,B,C,D): 80 Processing Functions K(0),
K(1), ..., K(79): 80 Processing Constant Words
H0, H1, H2, H3, H4, H5: 5 Word buffers with initial values
http://www.herongyang.com
12. SHA-1 Framework Continued
Step 6: Pseudo Code….
For loop on k = 1 to L
(W(0),W(1),...,W(15)) = M[k] /* Divide M[k] into 16 words */
For t = 16 to 79 do:
W(t) = (W(t-3) XOR W(t-8) XOR W(t-14) XOR W(t-16)) <<< 1
A = H0, B = H1, C = H2, D = H3, E = H4
For t = 0 to 79 do:
TEMP = A<<<5 + f(t;B,C,D) + E + W(t) + K(t) E = D, D = C,
C = B<<<30, B = A, A = TEMP
End of for loop
H0 = H0 + A, H1 = H1 + B, H2 = H2 + C, H3 = H3 + D, H4 = H4 + E
End of for loop
Output:
H0, H1, H2, H3, H4, H5: Word buffers with final message digest
http://www.herongyang.com
14. SHA-1 Message Digest
The message digest of the string:
“This is a test for theory of computation”
4480afca4407400b035d9debeb88bfc402db514f
15. Cryptanalysis and Limitation
• Key Premises for Hash Functions:
1. Impossible to re-create a message
given a fingerprint
2. Collision Free
• SHA-1 failure using brute force attack in 280 operations
• Collision failure found in 2005 in 233 operations
16. Bibliography
http://www.herongyang.com
http://www.ipa.go.jp/security
Salomon, David, Foundations of Computer
Security Springer-Verlag London Limited 2006.
Schneier, Bruce, “Opinion: Cryptanalysis of MD
% and SHA: Time for a new standard”,
Computer World, August 2004.
Stallings, William, Cryptography and Network
Security, Prentice Hall, 1999.
Tanenbaum, Andrew, Computer Networks,
Prentice Hall, 2003.
Editor's Notes
Verify that received messages come from the alleged source and have not been altered. Also verify the sequence and timing. Digital Signature is used to combat denial of receipt of a message by either the source or desitination.
All variants have a similar framework. The variation is in the bits compressed into the digest. Thereby, differ in the number of blocks and words of data used in hashing.