实现Python的实现SHA-256哈希算法但不直接调用函数库

SHA-256哈希算法是一种加密算法，用于将任意长度的消息转换为一个长度为256位的哈希值。下面是一个Python的实现，该实现不使用任何函数库直接实现SHA-256哈希算法。

import math

# 初始化常量
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
]

# 定义一些辅助函数
def rotr(x, n):
    return (x >> n) | (x << (32 - n))

def shr(x, n):
    return x >> n

def ch(x, y, z):
    return (x & y) ^ (~x & z)

def maj(x, y, z):
    return (x & y) ^ (x & z) ^ (y & z)

def sigma0(x):
    return rotr(x, 2) ^ rotr(x, 13) ^ rotr(x, 22)

def sigma1(x):
    return rotr(x, 6) ^ rotr(x, 11) ^ rotr(x, 25)

def gamma0(x):
    return rotr(x, 7) ^ rotr(x, 18) ^ shr(x, 3)

def gamma1(x):
    return rotr(x, 17) ^ rotr(x, 19) ^ shr(x, 10)

# 定义SHA-256哈希函数
def sha256(message):
    # 对消息进行预处理
    message = bytearray(message)
    ml = len(message) * 8
    message.append(0x80)
    while (len(message) * 8) % 512 != 448:
        message.append(0x00)
    message += ml.to_bytes(8, byteorder='big')

    # 初始化哈希值
    hash_values = h.copy()

    # 对消息进行分组
    for i in range(0, len(message), 64):
        # 将每个分组划分为16个字
        words = [int.from_bytes(message[j:j+4], byteorder='big')
                 for j in range(i, i+64, 4)]

        # 扩展16个字为64个字
        for j in range(16, 64):
            s0 = gamma0(words[j-15])
            s1 = gamma1(words[j-2])
            words.append((words[j-16] + s0 + words[j-7] + s1) & 0xffffffff)

        # 初始化临时变量
        a, b, c, d, e, f, g, h = hash_values

        # 进行64轮的压缩
        for j in range(64):
            S1 = sigma1(e)
            ch_val = ch(e, f, g)
            temp1 = (h + S1 + ch_val + k[j] + words[j]) & 0xffffffff
            S0 = sigma0(a)
            maj_val = maj(a, b, c)
            temp2 = (S0 + maj_val) & 0xffffffff

            h = g
            g = f
            f = e
            e = (d + temp1) & 0xffffffff
            d = c
            c = b
            b = a
            a = (temp1 + temp2) & 0xffffffff

        # 更新哈希值
        hash_values[0] = (hash_values[0] + a) & 0xffffffff
        hash_values[1] = (hash_values[1] + b) & 0xffffffff
        hash_values[2] = (hash_values[2] + c) & 0xffffffff
        hash_values[3] = (hash_values[3] + d) & 0xffffffff
        hash_values[4] = (hash_values[4] + e) & 0xffffffff
        hash_values[5] = (hash_values[5] + f) & 0xffffffff
        hash_values[6] = (hash_values[6] + g) & 0xffffffff
        hash_values[7] = (hash_values[7] + h) & 0xffffffff

    # 将哈希值转换为16进制字符串
    return ''.join(format(hv, '08x') for hv in hash_values)

使用示例：

message = b'Hello, world!'
print(sha256(message))
# 输出：b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9