Secure hashing algorithm
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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.
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![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](https://image.slidesharecdn.com/securehashingalgorithm-121216002452-phpapp01/85/Secure-hashing-algorithm-11-320.jpg)
![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](https://image.slidesharecdn.com/securehashingalgorithm-121216002452-phpapp01/85/Secure-hashing-algorithm-12-320.jpg)
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It describes how hash functions work by taking a message and producing a fixed-size hash value. SHA algorithms like SHA-1, SHA-256, SHA-384, and SHA-512 are described as secure hash functions developed by NIST. The document outlines the 5 steps of the SHA-512 algorithm: 1) append padding bits, 2) append length, 3) initialize hash buffer, 4) process message in blocks, and 5) output hash value.
HMAC is then introduced as a way to incorporate a secret key into an existing hash algorithm like MD5 or SHA-1 to produce a message authentication code
Hash mac algorithms
Hash mac algorithmsTony Nguyen This document discusses hash and MAC algorithms. It provides details on hash functions, the Secure Hash Algorithm (SHA), and HMAC.
Hash functions take a message and produce a fixed-size hash value. SHA is a secure hash algorithm developed by NIST that produces 160-bit or longer hash values. It works by padding the message, appending the length, initializing buffers, processing the message in blocks through compression functions, and outputting the hash value.
HMAC is a MAC algorithm that incorporates a secret key into an existing hash function like MD5 or SHA. It works by padding the key, XORing it with ipad or opad, appending the message or hash, and applying the hash function to produce the
Hash mac algorithms
Hash mac algorithmsLuis Goldster This document discusses hash and MAC algorithms. It provides details on hash functions, the Secure Hash Algorithm (SHA), and HMAC.
Hash functions take a message and produce a fixed-size hash value. SHA is a secure hash algorithm developed by NIST that produces 160-bit or longer hash values. It works by padding the message, appending the length, initializing buffers, processing the message in blocks through compression functions, and outputting the hash value.
HMAC is a MAC algorithm that incorporates a secret key into an existing hash function like MD5 or SHA. It works by padding the key, XORing it with ipad or opad, appending the message or hash, and applying the hash function to produce the
Hash mac algorithms
Hash mac algorithmsDavid Hoen This document discusses hash and MAC algorithms. It provides details on hash functions, the Secure Hash Algorithm (SHA), and HMAC.
Hash functions take a message and produce a fixed-size hash value. SHA is a secure hash algorithm developed by NIST that produces 160-bit or longer hash values. It works by padding and processing the message in blocks, using a compression function and initialization vector.
HMAC is a MAC algorithm that incorporates a secret key into the hashing process. It works by XORing the key with ipad and opad pads, hashing the padded message, and outputting the result. HMAC allows existing hash functions to be used for message authentication in a way that relies on the secret
Hash mac algorithms
Hash mac algorithmsJames Wong This document discusses hash and MAC algorithms. It provides details on hash functions, the Secure Hash Algorithm (SHA), and HMAC.
Hash functions take a message and produce a fixed-size hash value. SHA is a secure hash algorithm developed by NIST that produces 160-bit or longer hash values. It works by padding and processing the message in blocks, using a compression function and initialization vector.
HMAC is a MAC algorithm that incorporates a secret key into an existing hash function like MD5 or SHA. It works by XORing the key with ipad and opad pads, hashing the padded message, and outputting the result. HMAC executes with similar speed to the underlying hash function.
Hash& mac algorithms
Hash& mac algorithmsHarry Potter This document discusses hash and MAC algorithms. It provides details on hash functions, the Secure Hash Algorithm (SHA), and HMAC.
Hash functions take a message and produce a fixed-size hash value. SHA is a secure hash algorithm developed by NIST that produces 160-bit or longer hash values. It involves padding the message, initializing a buffer, processing the message in blocks through a compression function, and outputting the final hash.
HMAC is a MAC algorithm that incorporates a secret key into an existing hash function like MD5 or SHA. It pads and XORs the key, hashes the result with the message, then hashes again with a padded key to produce the MAC value.
Hash mac algorithms
Hash mac algorithmsYoung Alista The document discusses hash and MAC algorithms, focusing on Secure Hash Algorithms (SHA) and HMAC. It details the steps involved in SHA operations, particularly SHA-512, emphasizing the addition of padding, length, and the processing of message blocks using compression functions. HMAC is introduced as a method for constructing message authentication codes using existing hash functions, outlining its design objectives and security considerations.
Data streaming algorithms
Data streaming algorithmsHridyesh Bisht The document discusses data streaming algorithms, particularly focusing on approximate counting and hashing algorithms. It details concepts such as distinct elements counting, frequency estimation, and the workings of various hashing functions like MD5, SHA-1, and SHA-2. Additionally, it describes algorithms for approximating the f0-norm to count distinct items in data streams and highlights the applications of these algorithms in areas like data compression and artificial intelligence.
Hashfunction
HashfunctionFraboni Ec The document discusses hash functions and message authentication codes (MACs). It begins by defining hash functions and MACs, noting that hash functions generate a fingerprint for a message without a key while MACs use a keyed hash function. It then covers security requirements for hash functions like one-wayness and collision resistance. Popular hash functions are described like MD5, SHA-1, and the SHA-2 family. Constructions for hash functions based on block ciphers and iterated hash functions are also outlined. The document concludes by comparing hash functions and MACs and describing common MAC constructions.
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Secure hashing algorithm
- 1. SECURE HASHING ALGORITHM By: Ruth Betcher
- 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
- 6. Basic Hash Function Diagram
- 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
- 13. Message Diagram
- 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
- #3: 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.
- #6: 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.