Dada uma sequência de bytes, produza o valor de hash SHA-256 da sequência.

O algoritmo SHA-256

O pseudocódigo a seguir é retirado da página da Wikipedia para SHA-2 .

Note 1: All variables are 32 bit unsigned integers and addition is calculated modulo 2^32
Note 2: For each round, there is one round constant k[i] and one entry in the message schedule array w[i], 0 ≤ i ≤ 63
Note 3: The compression function uses 8 working variables, a through h
Note 4: Big-endian convention is used when expressing the constants in this pseudocode,
    and when parsing message block data from bytes to words, for example,
    the first word of the input message "abc" after padding is 0x61626380

Initialize hash values:
(first 32 bits of the fractional parts of the square roots of the first 8 primes 2..19):
h0 := 0x6a09e667
h1 := 0xbb67ae85
h2 := 0x3c6ef372
h3 := 0xa54ff53a
h4 := 0x510e527f
h5 := 0x9b05688c
h6 := 0x1f83d9ab
h7 := 0x5be0cd19

Initialize array of round constants:
(first 32 bits of the fractional parts of the cube roots of the first 64 primes 2..311):
k[0..63] :=
   0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
   0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
   0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
   0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
   0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
   0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
   0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
   0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2

Pre-processing:
append the bit '1' to the message
append k bits '0', where k is the minimum number >= 0 such that the resulting message
    length (modulo 512 in bits) is 448.
append length of message (without the '1' bit or padding), in bits, as 64-bit big-endian integer
    (this will make the entire post-processed length a multiple of 512 bits)

Process the message in successive 512-bit chunks:
break message into 512-bit chunks
for each chunk
    create a 64-entry message schedule array w[0..63] of 32-bit words
    (The initial values in w[0..63] don't matter, so many implementations zero them here)
    copy chunk into first 16 words w[0..15] of the message schedule array

    Extend the first 16 words into the remaining 48 words w[16..63] of the message schedule array:
    for i from 16 to 63
        s0 := (w[i-15] rightrotate 7) xor (w[i-15] rightrotate 18) xor (w[i-15] rightshift 3)
        s1 := (w[i-2] rightrotate 17) xor (w[i-2] rightrotate 19) xor (w[i-2] rightshift 10)
        w[i] := w[i-16] + s0 + w[i-7] + s1

    Initialize working variables to current hash value:
    a := h0
    b := h1
    c := h2
    d := h3
    e := h4
    f := h5
    g := h6
    h := h7

    Compression function main loop:
    for i from 0 to 63
        S1 := (e rightrotate 6) xor (e rightrotate 11) xor (e rightrotate 25)
        ch := (e and f) xor ((not e) and g)
        temp1 := h + S1 + ch + k[i] + w[i]
        S0 := (a rightrotate 2) xor (a rightrotate 13) xor (a rightrotate 22)
        maj := (a and b) xor (a and c) xor (b and c)
        temp2 := S0 + maj

        h := g
        g := f
        f := e
        e := d + temp1
        d := c
        c := b
        b := a
        a := temp1 + temp2

    Add the compressed chunk to the current hash value:
    h0 := h0 + a
    h1 := h1 + b
    h2 := h2 + c
    h3 := h3 + d
    h4 := h4 + e
    h5 := h5 + f
    h6 := h6 + g
    h7 := h7 + h

Produce the final hash value (big-endian):
digest := hash := h0 append h1 append h2 append h3 append h4 append h5 append h6 append h7

Implementação de referência

Aqui está uma implementação de referência, em Python 3:

#!/usr/bin/env python3

import sys

# ror function modified from http://stackoverflow.com/a/27229191/2508324
def ror(val, r_bits):
   return (val >> r_bits) | (val << (32-r_bits)) % 2**32

h = [0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19]

k = [0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
   0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
   0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
   0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
   0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
   0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
   0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
   0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2]

s = sys.stdin.read().encode()
msg = [int(x,2) for c in s for x in '{:08b}'.format(c)]
msg.append(1)
while len(msg) % 512 != 448:
    msg.append(0)
msg.extend([int(x,2) for x in '{:064b}'.format(len(s) * 8)])

for i in range(len(msg)//512):
    chunk = msg[512*i:512*(i+1)] # sloth love chunk
    w = [0 for _ in range(64)]
    for j in range(16):
        w[j] = int(''.join(str(x) for x in chunk[32*j:32*(j+1)]),2)
    for j in range(16, 64):
        s0 = ror(w[j-15], 7) ^ ror(w[j-15], 18) ^ (w[j-15] >> 3)
        s1 = ror(w[j-2], 17) ^ ror(w[j-2], 19) ^ (w[j-2] >> 10)
        w[j] = (w[j-16] + s0 + w[j-7] + s1) % 2**32
    work = h[:]
    for j in range(64):
        S1 = ror(work[4], 6) ^ ror(work[4], 11) ^ ror(work[4], 25)
        ch = (work[4] & work[5]) ^ (~work[4] & work[6])
        temp1 = (work[7] + S1 + ch + k[j] + w[j]) % 2**32
        S0 = ror(work[0], 2) ^ ror(work[0], 13) ^ ror(work[0], 22)
        maj = (work[0] & work[1]) ^ (work[0] & work[2]) ^ (work[1] & work[2])
        temp2 = (S0 + maj) % 2**32
        work = [(temp1 + temp2) % 2**32] + work[:-1]
        work[4] = (work[4] + temp1) % 2**32
    h = [(H+W)%2**32 for H,W in zip(h,work)]

print(''.join('{:08x}'.format(H) for H in h))

Restrições

• É proibido o uso de componentes internos que computam hashes SHA-256 ou que trivializam o desafio
• A entrada e a saída podem estar em qualquer formato razoável (codificado em uma byte, base64, hexadecimal, etc.)

Casos de teste

<empty string> -> e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
abc -> ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad
Hello, World! -> c98c24b677eff44860afea6f493bbaec5bb1c4cbb209c6fc2bbb47f66ff2ad31
1234 -> 03ac674216f3e15c761ee1a5e255f067953623c8b388b4459e13f978d7c846f4

J , 458 445 443 438 435 430 421 bytes

3 :0
B=.32#2
A=.B&#:
P=.+&#.
'H K'=.A<.32*&2(-<.)2 3%:/p:i.64
for_m._512]\(,(1{.~512|448-#),(,~B)#:#)y
do.w=.(,B#:(15&|.~:13&|.~:_10|.!.0])@(_2&{)P/@,(25&|.~:14&|.~:_3|.!.0])@(_15&{),_7 _16&{)^:48]_32]\m
'a b c d e f g h'=.H=.8{.H
for_t.i.64
do.u=.A]P/((e<g)~:e*f),h,(~:/26 21 7|."{e),t{&>K;w
v=.A(a*b)P(c*a~:b)P~:/30 19 10|."{a
h=.g
g=.f
f=.e
e=.A]d P u
d=.c
c=.b
b=.a
a=.A]u P v
end.
H=.A]H P a,b,c,d,e,f,g,:h
end.
,H
)

Experimente online!

Este é um verbo monádico que recebe uma lista de bits como entrada e gera uma lista de bits. No TIO, a conversão de string em lista de bits para a entrada e lista de bits em hexadecimal é implementada por conveniência. Para testar outra entrada, basta modificar o texto no inputcampo.

Python 2, 519 bytes

Q=2**32
G=lambda e:[int(x**e%1*Q)for x in range(2,312)if 383**~-x%x<2]
H=G(.5)[:8]
r=lambda v,b:v>>b|v<<32-b
M=input()
l=len(M)
M+=bin(l|1<<(447-l)%512+64)[2:]
while M:j=0;a,b,c,d,e,f,g,h=H;exec"H+=int(M[:32],2),;M=M[32:];"*16+"x=H[-15];y=H[-2];H+=(H[-16]+H[-7]+(r(y,17)^r(y,19)^y>>10)+(r(x,7)^r(x,18)^x/8))%Q,;"*48+"u=(r(e,6)^r(e,11)^r(e,25))+(e&f^~e&g)+h+G(1/3.)[j]+H[j+8];X=a,b,c,d,e,f,g,h=(u+(r(a,2)^r(a,13)^r(a,22))+(a&b^a&c^b&c))%Q,a,b,c,(d+u)%Q,e,f,g;j+=1;"*64;H=tuple(a+b&Q-1for a,b in zip(H,X))
print"%08x"*8%H

Eu estava trabalhando fora do pseudocódigo, mas algumas partes apenas acabou sendo o mesmo que o de referência golfed Mego postou uma vez que não há muito a golf (por exemplo, as tabelas constantes, para o qual o golf única verdadeira era uma <2vez de ==1). Mais de 100 bytes abaixo, mas tenho certeza de que ainda há mais a serem obtidos.

Entrada / saída também é uma sequência de bits para uma sequência hexadecimal.

Python 2, 633 bytes

n=range
f=2**32
q=512
r=lambda v,b:v%f>>b|(v<<32-b)%f
t=int
g=lambda e:[t(x**e%1*f)for x in n(2,312)if 383**~-x%x==1]
h=g(.5)
k=g(1/3.)
m=map(t,input())
l=len(m)
m+=[1]+[0]*((447-l)%q)+map(t,'{:064b}'.format(l))
for i in n(l/q+1):
 c=m[q*i:][:q];w=[t(`c[j*32:][:32]`[1::3],2) for j in n(16)];x=h[:8]
 for j in n(48):a,o=w[j+1],w[j+14];w+=[(w[j]+(r(a,7)^r(a,18)^(a>>3))+w[j+9]+(r(o,17)^r(o,19)^(o>>10)))%f]
 for j in n(64):a,o=x[::4];d=x[7]+(r(o,6)^r(o,11)^r(o,25))+(o&x[5]^~o&x[6])+k[j]+w[j];e=(r(a,2)^r(a,13)^r(a,22))+(x[1]&a|x[2]&a|x[1]&x[2]);x=[d+e]+x[:7];x[4]+=d
 h=[(H+W)%f for H,W in zip(h,x)]
print''.join('%08x'%H for H in h)

Essa solução é o resultado de uma colaboração entre mim, Leaky Nun e Mars Ultor. Como tal, eu criei o wiki da comunidade por justiça. Ele recebe a entrada como uma sequência binária envolvida em aspas (por exemplo, '011000010110001001100011'para abc) e gera uma sequência hexadecimal.

C, 1913 1822 bytes (apenas por diversão)

#define q unsigned
#define D(a,c)x->b[1]+=a>1<<33-1-c;a+=c;
#define R(a,b)(a>>b|a<<32-b)
#define S(x,a,b,c)(R(x,a)^R(x,b)^x>>c)
#define W(i,a)i=x->s[a];
#define Y(i,a)x->s[a]+=i;
#define Z(_,a)h[i+a*4]=x->s[a]>>(24-i*8);
#define J(a)x->d[a]
#define T(_,a)x->d[63-a]=x->b[a/4]>>8*(a%4);
#define Q(_,a)x->s[a]=v[a];
#define A(F)F(a,0)F(b,1)F(c,2)F(d,3)F(e,4)F(f,5)F(g,6)F(h,7)
#define G(a,b)for(i=a;i<b;++i)
typedef struct{q char d[64];q l,b[2],s[8];}X;q k[]={0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070,0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2},v[]={0x6a09e667,0xbb67ae85,0x3c6ef372,0xa54ff53a,0x510e527f,0x9b05688c,0x1f83d9ab,0x5be0cd19};a(X*x){q a,b,c,d,e,f,g,h,i,t,z,m[64];G(z=0,16)m[i]=J(z++)<<24|J(z++)<<16|J(z++)<<8|J(z++);G(i,64)m[i]=S(m[i-2],17,19,10)+m[i-7]+S(m[i-15],7,18,3)+m[i-16];A(W);G(0,64){t=h+(R(e,6)^R(e,11)^R(e,25))+(e&f^~e&g)+k[i]+m[i];z=(R(a,2)^R(a,13)^R(a,22))+(a&b^a&c^b&c);h=g;g=f;f=e;e=d+t;d=c;c=b;b=a;a=t+z;}A(Y)}i(X*x){x->l=*x->b=x->b[1]=0;A(Q)}p(X*x,char*w,q l){q t,i;G(0,l){J(x->l)=w[i];if(++x->l==64){a(x);D(*x->b,512)x->l=0;}}}f(X*x,char*h){q i=x->l;if(i<56){J(i++)=128;G(i,56)J(i)=0;}else{J(i++)=128;G(i,64)J(i)=0;a(x);G(0,56)J(i)=0;}D(*x->b,x->l*8)A(T)a(x);G(0,4){A(Z)}}

Peguei a implementação de referência e comecei a jogar golfe, meu objetivo estava abaixo de 2k.

Pode ser melhorado se alguém souber gerar as constantes (raiz cúbica de números primos, não consigo pensar em nenhuma maneira favorável ao golfe).

Uso:

X ctx;
unsigned char hash[32];

i(&ctx);                    // initialize context
p(&ctx,text,strlen(text));  // hash string
f(&ctx,hash);               // get hash