SHA-256 Hashing(0)

全体を通して、一番短縮し甲斐のありそうな問題です。とりあえずは、
http://en.wikipedia.org/wiki/SHA_hash_functions
を参考にそのままコードを書いてみました。普通に解く時点で手間取るとショートコード熱が冷めてしまう可能性があるので、忙しいけど縮めたくてたまらん人は参考にどうぞ。

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]


input = message =""
w = []
size = n = 0
$mask32 = (1<<32)-1

[message += input]while input = gets

message.split('').map{|c|
	n = n<<8
	n += c[0]
	size += 1
}

size*=8
block = (size+64)/512

n=n<<1
n+=1

lastBlockSize = size%512 + 1
if lastBlockSize > 448
	n = n<<(512-(lastBlockSize-448))
else 
	n = n<<(448-lastBlockSize)
end

n=n<<64
n+=size
#printf("%x %x\n\n",size, n)

#右回転シフト
def rotate(w,n)
	t=w&((1<<n)-1)
	t=((t<<(32-n))|(w>>n))&$mask32
#	printf("%08x\n", t)
	t
end

block.downto(0){|mi|

	15.downto(0){|i|
		w[i]=((n>>(mi*512))>>((15-i)*32))%(1<<32)
#		printf("w[%2d] = %08x\n",i,w[i])
	}

	16.upto(63){|i|
		w0 = w[i-15]; w1 = w[i-2]
		s0 = rotate(w0,7)^rotate(w0,18)^(w0>>3)
		s1 = rotate(w1,17)^rotate(w1,19)^(w1>>10)
		w[i] = (w[i-16] + s0 + w[i-7] + s1)&$mask32
	}

	a = H[0]
	b = H[1]
	c = H[2]
	d = H[3]
	e = H[4]
	f = H[5]
	g = H[6]
	h = H[7]

	0.upto(63){|i|
		s0 = rotate(a,2)^rotate(a,13)^rotate(a,22)
		maj = (a&b)^(a&c)^(b&c)
		t2 = s0 + maj
		s1 = rotate(e,6)^rotate(e,11)^rotate(e,25)
		ch = (e&f)^((~e)&g)
		t1 = h + s1 + ch + K[i] + w[i]

		h = g
		g = f
		f = e
		e = (d + t1)&$mask32
		d = c
		c = b
		b = a
		a = (t1 + t2)&$mask32
	}

	H[0] = (H[0]+a)&$mask32
	H[1] = (H[1]+b)&$mask32
	H[2] = (H[2]+c)&$mask32
	H[3] = (H[3]+d)&$mask32
	H[4] = (H[4]+e)&$mask32
	H[5] = (H[5]+f)&$mask32
	H[6] = (H[6]+g)&$mask32
	H[7] = (H[7]+h)&$mask32
}

0.upto(7){|i|printf("%08x",H[i])}