A small scaled version of SHA256 algorithm using C++, the program takes the hexadecimal equivalent of a text and produces its corresponding hash.
After the first 16digits initial 32bit digits are found, next (64-16)digits can be found using
W(i) = Wⁱ⁻¹⁶ + σ⁰ + Wⁱ⁻⁷ + σ¹
where,
σ⁰ = (Wⁱ⁻¹⁵ ROTR⁷(x)) XOR (Wⁱ⁻¹⁵ ROTR¹⁸(x)) XOR (Wⁱ⁻¹⁵ SHR³(x))
σ¹ = (Wⁱ⁻² ROTR¹⁷(x)) XOR (Wⁱ⁻² ROTR¹⁹(x)) XOR (Wⁱ⁻² SHR¹⁰(x))
ROTRⁿ(x) = Circular right rotation of 'x' by 'n' bits
SHRⁿ(x) = Circular right shift of 'x' by 'n' bits\
To find the hash, we use 6 initial hashes and 64 initial constants, which are :
A = 0x6a09e667
B = 0xbb67ae85
C = 0x3c6ef372
D = 0xa54ff53a
E = 0x510e527f
F = 0x9b05688c
G = 0x1f83d9ab
H = 0x5be0cd19
Then we run the final step using all of this
Ch(E, F, G) = (E AND F) XOR ((NOT E) AND G)
Ma(A, B, C) = (A AND B) XOR (A AND C) XOR (B AND C)
∑(A) = (A >>> 2) XOR (A >>> 13) XOR (A >>> 22)
∑(E) = (E >>> 6) XOR (E >>> 11) XOR (E >>> 25)+
= addition modulo 2³²