/*
 * Copyright (c) 2012-2020 MIRACL UK Ltd.
 *
 * This file is part of MIRACL Core
 * (see https://github.com/miracl/core).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * Implementation of the Secure Hashing Algorithm (SHA-384)
 *
 * Generates a 384 bit message digest. It should be impossible to come
 * come up with two messages that hash to the same value ("collision free").
 *
 * For use with byte-oriented messages only.
 */

package core

//import "fmt"

const SHA512 int = 64

const hash512_H0 uint64 = 0x6a09e667f3bcc908
const hash512_H1 uint64 = 0xbb67ae8584caa73b
const hash512_H2 uint64 = 0x3c6ef372fe94f82b
const hash512_H3 uint64 = 0xa54ff53a5f1d36f1
const hash512_H4 uint64 = 0x510e527fade682d1
const hash512_H5 uint64 = 0x9b05688c2b3e6c1f
const hash512_H6 uint64 = 0x1f83d9abfb41bd6b
const hash512_H7 uint64 = 0x5be0cd19137e2179

var hash512_K = [...]uint64{
	0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f, 0xe9b5dba58189dbbc,
	0x3956c25bf348b538, 0x59f111f1b605d019, 0x923f82a4af194f9b, 0xab1c5ed5da6d8118,
	0xd807aa98a3030242, 0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
	0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235, 0xc19bf174cf692694,
	0xe49b69c19ef14ad2, 0xefbe4786384f25e3, 0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65,
	0x2de92c6f592b0275, 0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
	0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f, 0xbf597fc7beef0ee4,
	0xc6e00bf33da88fc2, 0xd5a79147930aa725, 0x06ca6351e003826f, 0x142929670a0e6e70,
	0x27b70a8546d22ffc, 0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
	0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6, 0x92722c851482353b,
	0xa2bfe8a14cf10364, 0xa81a664bbc423001, 0xc24b8b70d0f89791, 0xc76c51a30654be30,
	0xd192e819d6ef5218, 0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8,
	0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99, 0x34b0bcb5e19b48a8,
	0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb, 0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3,
	0x748f82ee5defb2fc, 0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec,
	0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915, 0xc67178f2e372532b,
	0xca273eceea26619c, 0xd186b8c721c0c207, 0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178,
	0x06f067aa72176fba, 0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b,
	0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc, 0x431d67c49c100d4c,
	0x4cc5d4becb3e42b6, 0x597f299cfc657e2a, 0x5fcb6fab3ad6faec, 0x6c44198c4a475817}

type HASH512 struct {
	length [2]uint64
	h      [8]uint64
	w      [80]uint64
}

/* functions */
func hash512_S(n uint64, x uint64) uint64 {
	return (((x) >> n) | ((x) << (64 - n)))
}

func hash512_R(n uint64, x uint64) uint64 {
	return ((x) >> n)
}

func hash512_Ch(x, y, z uint64) uint64 {
	return ((x & y) ^ (^(x) & z))
}

func hash512_Maj(x, y, z uint64) uint64 {
	return ((x & y) ^ (x & z) ^ (y & z))
}

func hash512_Sig0(x uint64) uint64 {
	return (hash512_S(28, x) ^ hash512_S(34, x) ^ hash512_S(39, x))
}

func hash512_Sig1(x uint64) uint64 {
	return (hash512_S(14, x) ^ hash512_S(18, x) ^ hash512_S(41, x))
}

func hash512_theta0(x uint64) uint64 {
	return (hash512_S(1, x) ^ hash512_S(8, x) ^ hash512_R(7, x))
}

func hash512_theta1(x uint64) uint64 {
	return (hash512_S(19, x) ^ hash512_S(61, x) ^ hash512_R(6, x))
}

func (H *HASH512) transform() { /* basic transformation step */
	for j := 16; j < 80; j++ {
		H.w[j] = hash512_theta1(H.w[j-2]) + H.w[j-7] + hash512_theta0(H.w[j-15]) + H.w[j-16]
	}
	a := H.h[0]
	b := H.h[1]
	c := H.h[2]
	d := H.h[3]
	e := H.h[4]
	f := H.h[5]
	g := H.h[6]
	hh := H.h[7]
	for j := 0; j < 80; j++ { /* 80 times - mush it up */
		t1 := hh + hash512_Sig1(e) + hash512_Ch(e, f, g) + hash512_K[j] + H.w[j]
		t2 := hash512_Sig0(a) + hash512_Maj(a, b, c)
		hh = g
		g = f
		f = e
		e = d + t1
		d = c
		c = b
		b = a
		a = t1 + t2
	}
	H.h[0] += a
	H.h[1] += b
	H.h[2] += c
	H.h[3] += d
	H.h[4] += e
	H.h[5] += f
	H.h[6] += g
	H.h[7] += hh
}

/* Initialise Hash function */
func (H *HASH512) Init() { /* initialise */
	for i := 0; i < 80; i++ {
		H.w[i] = 0
	}
	H.length[0] = 0
	H.length[1] = 0
	H.h[0] = hash512_H0
	H.h[1] = hash512_H1
	H.h[2] = hash512_H2
	H.h[3] = hash512_H3
	H.h[4] = hash512_H4
	H.h[5] = hash512_H5
	H.h[6] = hash512_H6
	H.h[7] = hash512_H7
}

func NewHASH512() *HASH512 {
	H := new(HASH512)
	H.Init()
	return H
}

func NewHASH512copy(HC *HASH512) *HASH512 {
	H := new(HASH512)
	for i := 0; i < 80; i++ {
		H.w[i] = HC.w[i]
	}
	for i := 0; i < 8; i++ {
		H.h[i] = HC.h[i]
	}
	H.length[0] = HC.length[0]
	H.length[1] = HC.length[1]
	return H
}

/* process a single byte */
func (H *HASH512) Process(byt byte) { /* process the next message byte */
	cnt := (H.length[0] / 64) % 16

	H.w[cnt] <<= 8
	H.w[cnt] |= uint64(byt & 0xFF)
	H.length[0] += 8
	if H.length[0] == 0 {
		H.length[1]++
		H.length[0] = 0
	}
	if (H.length[0] % 1024) == 0 {
		H.transform()
	}
}

/* process an array of bytes */
func (H *HASH512) Process_array(b []byte) {
	for i := 0; i < len(b); i++ {
		H.Process((b[i]))
	}
}

/* process a 32-bit integer */
func (H *HASH512) Process_num(n int32) {
	H.Process(byte((n >> 24) & 0xff))
	H.Process(byte((n >> 16) & 0xff))
	H.Process(byte((n >> 8) & 0xff))
	H.Process(byte(n & 0xff))
}

/* Generate 64-byte Hash */
func (H *HASH512) Hash() []byte { /* pad message and finish - supply digest */
	var digest [64]byte
	len0 := H.length[0]
	len1 := H.length[1]
	H.Process(0x80)
	for (H.length[0] % 1024) != 896 {
		H.Process(0)
	}
	H.w[14] = len1
	H.w[15] = len0
	H.transform()
	for i := 0; i < 64; i++ { /* convert to bytes */
		digest[i] = byte((H.h[i/8] >> uint(8*(7-i%8))) & 0xff)
	}
	H.Init()
	return digest[0:64]
}

func (H *HASH512) Continuing_Hash() []byte {
	sh := NewHASH512copy(H)
	return sh.Hash()
}

/* test program: should produce digest */

//8e959b75dae313da 8cf4f72814fc143f 8f7779c6eb9f7fa1 7299aeadb6889018 501d289e4900f7e4 331b99dec4b5433a c7d329eeb6dd2654 5e96e55b874be909
/*
func main() {

	test := []byte("abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu")
	sh:=NewHASH512()

	for i:=0;i<len(test);i++ {
		sh.Process(test[i])
	}

	digest:=sh.Hash()
	for i:=0;i<64;i++ {fmt.Printf("%02x",digest[i])}

}
*/