Pythonでハッシュ関数とバイナリデータのチェックサム計算を理解する

import hashlib

# ハッシュ対象の文字列
data = "Hello, World!"

# MD5ハッシュの計算
md5_hash = hashlib.md5(data.encode()).hexdigest()

print(f"MD5: {md5_hash}")

# SHA-256ハッシュの計算
sha256_hash = hashlib.sha256(data.encode()).hexdigest()

print(f"SHA-256: {sha256_hash}")

def calculate_hash(data, algorithm='sha256'):
    hash_func = getattr(hashlib, algorithm)
    return hash_func(data.encode()).hexdigest()

# 使用例
print(calculate_hash("Hello, World!", "md5"))
print(calculate_hash("Hello, World!", "sha256"))

import hashlib

data = "example"
md5_hash = hashlib.md5(data.encode()).hexdigest()
print(f"MD5: {md5_hash}")

sha1_hash = hashlib.sha1(data.encode()).hexdigest()
print(f"SHA-1: {sha1_hash}")

sha256_hash = hashlib.sha256(data.encode()).hexdigest()
print(f"SHA-256: {sha256_hash}")

sha3_256_hash = hashlib.sha3_256(data.encode()).hexdigest()
print(f"SHA-3-256: {sha3_256_hash}")

import zlib

data = b"example data"
crc32_checksum = zlib.crc32(data)
print(f"CRC32: {crc32_checksum}")

import zlib

# データの準備
data = b"example data"

# CRC32チェックサムの計算
crc32_checksum = zlib.crc32(data)

# チェックサムの表示
print(f"CRC32: {crc32_checksum}")

# ファイルのパス
file_path = 'example_file.txt'

# ファイルをバイナリモードで読み込み、チェックサムを計算
with open(file_path, 'rb') as file:
    data = file.read()
    crc32_checksum = zlib.crc32(data)

print(f"CRC32 of file: {crc32_checksum}")

# Adler-32チェックサムの計算
adler32_checksum = zlib.adler32(data)
print(f"Adler-32: {adler32_checksum}")

import zlib

def calculate_crc32(file_path):
    with open(file_path, 'rb') as file:
        data = file.read()
        return zlib.crc32(data)

# チェックサムを計算するファイルのパス
file_path = 'example_file.txt'
checksum = calculate_crc32(file_path)

# チェックサムをファイルに保存
with open(file_path + '.crc32', 'w') as checksum_file:
    checksum_file.write(f"{checksum}\n")

print(f"CRC32 checksum for {file_path}: {checksum}")

def verify_crc32(file_path):
    # 元のファイルのチェックサムを計算
    original_checksum = calculate_crc32(file_path)

    # 保存されたチェックサムを読み込み
    with open(file_path + '.crc32', 'r') as checksum_file:
        saved_checksum = int(checksum_file.read().strip())

    # チェックサムの比較
    if original_checksum == saved_checksum:
        print("File integrity verified: Checksums match.")
    else:
        print("File integrity check failed: Checksums do not match.")

# 整合性を確認するファイルのパス
file_path = 'example_file.txt'
verify_crc32(file_path)

import hashlib

def calculate_sha256(file_path):
    sha256 = hashlib.sha256()
    with open(file_path, 'rb') as file:
        for block in iter(lambda: file.read(4096), b""):
            sha256.update(block)
    return sha256.hexdigest()

# SHA-256チェックサムを計算するファイルのパス
file_path = 'example_file.txt'
sha256_checksum = calculate_sha256(file_path)

# チェックサムをファイルに保存
with open(file_path + '.sha256', 'w') as checksum_file:
    checksum_file.write(f"{sha256_checksum}\n")

print(f"SHA-256 checksum for {file_path}: {sha256_checksum}")

def verify_sha256(file_path):
    # 元のファイルのチェックサムを計算
    original_checksum = calculate_sha256(file_path)

    # 保存されたチェックサムを読み込み
    with open(file_path + '.sha256', 'r') as checksum_file:
        saved_checksum = checksum_file.read().strip()

    # チェックサムの比較
    if original_checksum == saved_checksum:
        print("File integrity verified: Checksums match.")
    else:
        print("File integrity check failed: Checksums do not match.")

# 整合性を確認するファイルのパス
file_path = 'example_file.txt'
verify_sha256(file_path)

try:
    # エラーが発生する可能性のあるコード
    result = 1 / 0
except ZeroDivisionError:
    # ZeroDivisionErrorが発生した場合の処理
    print("Error: Division by zero is not allowed.")

file_path = 'non_existent_file.txt'

try:
    with open(file_path, 'rb') as file:
        data = file.read()
        checksum = zlib.crc32(data)
        print(f"CRC32: {checksum}")
except FileNotFoundError:
    print(f"Error: The file {file_path} was not found.")
except PermissionError:
    print(f"Error: Permission denied for file {file_path}.")

def calculate_crc32(file_path):
    try:
        with open(file_path, 'rb') as file:
            data = file.read()
            return zlib.crc32(data)
    except FileNotFoundError:
        print(f"Error: The file {file_path} was not found.")
        return None
    except PermissionError:
        print(f"Error: Permission denied for file {file_path}.")
        return None
    except Exception as e:
        print(f"An unexpected error occurred: {e}")
        return None

file_path = 'example_file.txt'
checksum = calculate_crc32(file_path)
if checksum is not None:
    print(f"CRC32 checksum: {checksum}")

def get_file_path():
    return input("Enter the file path: ")

file_path = get_file_path()
while True:
    try:
        with open(file_path, 'rb') as file:
            data = file.read()
            checksum = zlib.crc32(data)
            print(f"CRC32: {checksum}")
        break
    except FileNotFoundError:
        print(f"Error: The file {file_path} was not found. Please try again.")
        file_path = get_file_path()
    except PermissionError:
        print(f"Error: Permission denied for file {file_path}. Please try again.")
        file_path = get_file_path()
    except Exception as e:
        print(f"An unexpected error occurred: {e}")
        break

import hashlib

def calculate_md5(file_path):
    try:
        with open(file_path, 'rb') as file:
            data = file.read()
            return hashlib.md5(data).hexdigest()
    except FileNotFoundError:
        print(f"Error: The file {file_path} was not found.")
    except PermissionError:
        print(f"Error: Permission denied for file {file_path}.")
    except Exception as e:
        print(f"An unexpected error occurred: {e}")

file_path = input("Enter the path to the text file: ")
md5_hash = calculate_md5(file_path)
if md5_hash:
    print(f"MD5 hash: {md5_hash}")

import hashlib

def calculate_sha256(file_path):
    try:
        sha256 = hashlib.sha256()
        with open(file_path, 'rb') as file:
            for block in iter(lambda: file.read(4096), b""):
                sha256.update(block)
        return sha256.hexdigest()
    except FileNotFoundError:
        print(f"Error: The file {file_path} was not found.")
    except PermissionError:
        print(f"Error: Permission denied for file {file_path}.")
    except Exception as e:
        print(f"An unexpected error occurred: {e}")

def verify_sha256(file_path):
    original_checksum = calculate_sha256(file_path)
    if not original_checksum:
        return

    checksum_file_path = file_path + '.sha256'
    try:
        with open(checksum_file_path, 'r') as checksum_file:
            saved_checksum = checksum_file.read().strip()
        if original_checksum == saved_checksum:
            print("File integrity verified: Checksums match.")
        else:
            print("File integrity check failed: Checksums do not match.")
    except FileNotFoundError:
        print(f"Error: The checksum file {checksum_file_path} was not found.")
    except PermissionError:
        print(f"Error: Permission denied for file {checksum_file_path}.")
    except Exception as e:
        print(f"An unexpected error occurred: {e}")

file_path = input("Enter the path to the file: ")
verify_sha256(file_path)