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Learning Opportunities
This puzzle can be solved using the following concepts. Practice using these concepts and improve your skills.
Statement
Goal
Implement a slightly modified version of the SHA-256 hash.A full description of the SHA-256 algorithm can be found on Wikipedia: https://en.wikipedia.org/wiki/SHA-2#Pseudocode
A detailed walkthrough can be found here: https://qvault.io/cryptography/how-sha-2-works-step-by-step-sha-256/
The only difference between the standard implementation (detailed in the 2 links above) and our implementation is in the definition of the initial hash values (referred to as h0 - h7 in the links above).
The standard implementation uses the first 32 bits of the fractional parts of the square roots of the first 8 primes (2, 3, 5, 7, 11, 13, 17, 19). We will instead use the first 32 bits of the fractional parts of the square roots of the next 8 primes (23, 29, 31, 37, 41, 43, 47, 53), given here in hexadecimal form:
0xcbbb9d5d
0x629a292a
0x9159015a
0x152fecd8
0x67332667
0x8eb44a87
0xdb0c2e0d
0x47b5481d
The reason we're using different initial hash values is so that you can't use built-in hash functions, e.g. python's hashlib.sha256.
Apart from this change in initial hash values, the algorithm proceeds exactly the same as the standard implementation. Note: the "round constants" are not changed, i.e. they are the same as in the standard implementation.
You will be given a string, you must convert that string to a sequence of bits (using ASCII) and hash it using our version of the SHA-256 algorithm.
Input
One line: a string S to hash.
Output
One line: the 64-character hash value H output by our version of the SHA-256 algorithm in lowercase hexadecimal form.
Constraints
All characters of the string will be printable ASCII characters in the range [32 - 126] inclusive.
Example
Input
Ravenclaw
Output
70ac5b0feb57d7b1823a905a398863318594dd996d5c40ecced5089935e7a922
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