Python利用RSA非对称加密方式_对任意文件进行加解密操作

朱雀 2023-01-17 07:42 131阅读 0赞

*python环境装好pycryptodome库*

### 一、首先创建密钥对 ###

from Crypto import Random
    from Crypto.PublicKey import RSA
     
    rsa = RSA.generate(1024, Random.new().read)
    # 私钥的生成
    private_pem = rsa.exportKey()
    with open("private.pem", "wb") as f:
        f.write(private_pem)
    # 公钥的生成
    public_pem = rsa.publickey().exportKey()
    with open("public.pem", "wb") as f:
        f.write(public_pem)

### 二、加密过程（读写模式均为二进制"b"所以可以对任意文件进行加解密操作） ###

from Crypto.PublicKey import RSA
    from Crypto.Cipher import PKCS1_v1_5
    from base64 import b64encode
    
    Plaintext_path = "./test.txt"
    Public_key_path = "./public.pem"
    
    with open(Plaintext_path, "rb") as f:  # , encoding ='utf-8'
        Plaintext = f.read()
    
    # 加密
    rsa_key = RSA.importKey(open(Public_key_path).read())
    cipher = PKCS1_v1_5.new(rsa_key)
    cipher_text = b64encode(cipher.encrypt(Plaintext))
    
    # print(cipher_text.decode('utf-8'))
    with open("cipher.txt", "wb") as f:
        f.write(cipher_text)
    print("Encryption Done...")

### 三、解密过程 ###

from Crypto.PublicKey import RSA
    from Crypto.Cipher import PKCS1_v1_5
    from base64 import b64decode
    
    Cipher_text_path = "./cipher.txt"
    Private_key_path = "./private.pem"
    
    with open(Cipher_text_path, "rb") as f:
        Cipher_text = f.read()
    
    # 解密
    rsakey = RSA.importKey(open(Private_key_path).read())
    cipher = PKCS1_v1_5.new(rsakey)
    Plaintext = cipher.decrypt(b64decode(Cipher_text), "解密失败")
    
    # print(Plaintext.decode('utf-8'))
    with open("result.txt", "wb") as f:
        f.write(Plaintext)
    print("Decryption Done...")

**    上述简单加密代码无法加密大文件，因为加密算法对密钥长度和明文长度有限制，加密的 plaintext 最大长度是 证书key位数/8 - 11, 例如1024 bit的证书，被加密的串最长 1024/8 - 11=117**

> 错误信息ValueError: Plaintext is too long.
> 
> message : byte string. The message to encrypt, also known as plaintext. It can be of variable length, but not longer than the RSA modulus (in bytes) minus 11.

**    以下代码采取分段加密解密就可以完成对任意文件的加密解密**

### 四、大文件加密过程 ###

from Crypto.PublicKey import RSA
    from Crypto.Cipher import PKCS1_v1_5
    
    Plaintext_path = "ab"  # 要加密的明文文件
    Cipher_text = "cd"  # 加密好的密文文件
    Public_key_path = "public.pem"  # 加密密钥文件
    certificate_length = 1024 # 证书key位数
    
    with open(Plaintext_path, "rb") as f:
        Plaintext = f.read()
    
    """
    单次加密串的长度最大为 (key_size/8)-11
    1024bit的证书用100， 2048bit的证书用 200
    """
    rsa_key = RSA.importKey(open(Public_key_path).read())
    cipher = PKCS1_v1_5.new(rsa_key)
    # cipher_text = b64encode(cipher.encrypt(Plaintext))
    cipher_text_ = []
    length = int(certificate_length / 8 - 11)
    for i in range(0, len(Plaintext), length):
        cipher_text_.append(cipher.encrypt(Plaintext[i:i + length]))
    cipher_text = b""
    for item in cipher_text_:
        cipher_text += item
    
    with open(Cipher_text, "wb") as f:
        f.write(cipher_text)
    print("Encryption Done...")

### 五、大文件解密过程 ###

from Crypto.PublicKey import RSA
    from Crypto.Cipher import PKCS1_v1_5
    
    Cipher_text_path = "cd"  # 密文文件
    Plaintext_path = "ef"  # 解密出的明文文件
    Private_key_path = "private.txt"  # 解密密钥文件
    certificate_length = 1024 # 证书key位数
    
    with open(Cipher_text_path, "rb") as f:
        Cipher_text = f.read()
    
    """
    单次解密长度
    1024bit的证书用128，2048bit证书用256位
    """
    rsakey = RSA.importKey(open(Private_key_path).read())
    cipher = PKCS1_v1_5.new(rsakey)
    # Plaintext = cipher.decrypt(b64decode(Cipher_text), "解密失败")
    Plaintext_ = []
    length = int(certificate_length / 8)
    for i in range(0, len(Cipher_text), length):
        Plaintext_.append(cipher.decrypt(Cipher_text[i:i + length], "解密失败"))
    Plaintext = b""
    for item in Plaintext_:
        Plaintext += item
    
    with open(Plaintext_path, "wb") as f:
        f.write(Plaintext)
    print("Decryption Done...")

### 六、添加进度条与命令行参数 ###

没有进度条太不用户友好了，RSA解密需要较长时间，稍微大一点的文件就需要很长时间，比较适合私密的小文件传输，不适合大文件加密解密。

**加密**

from Crypto.PublicKey import RSA
    from Crypto.Cipher import PKCS1_v1_5
    from argparse import ArgumentParser
    import time
    
    parser = ArgumentParser(description="这是RSA加密程序.", epilog="你学废了吗？")
    parser.add_argument("-p", "--plain", type=str, default=r"./ab", help="明文路径")
    parser.add_argument("-c", "--cipher", type=str, default=r"./cd", help="密文输出路径")
    parser.add_argument("--public", type=str, default=r"./public.pem", help="加密密钥路径")
    parser.add_argument("--cerlen", type=int, default=1024, help="证书key位数")
    args = parser.parse_args()
    
    with open(args.plain, "rb") as f:
        Plaintext = f.read()
    
    """
    单次加密串的长度最大为 (key_size/8)-11
    """
    rsa_key = RSA.importKey(open(args.public).read())
    cipher = PKCS1_v1_5.new(rsa_key)
    # cipher_text = b64encode(cipher.encrypt(Plaintext))
    cipher_text_ = []
    length = int(args.cerlen / 8 - 11)
    group = len(Plaintext) // length + 1
    process_bar_len = 20
    start = time.perf_counter()
    for i in range(0, len(Plaintext), length):
        cipher_text_.append(cipher.encrypt(Plaintext[i:i + length]))
        # print("一共",group,"段，第",i//length,"段完成")
        dur = time.perf_counter() - start
        count = i // length + 1
        finished = count / group  # 完成的百分比
        print("\rencryption progress:", "{}/{} ={:^3.0f}% ~{:.3f}s".format(count, group, finished * 100, dur),
              "★" * (int(process_bar_len * finished)), "☆" * (int(process_bar_len * (1 - finished))), end="")
    cipher_text = b""
    for item in cipher_text_:
        cipher_text += item
    
    with open(args.cipher, "wb") as f:
        f.write(cipher_text)
    print("\n" + args.plain + " ■ Encryption Done...")
    print("Output:", args.cipher)

**解密**

from Crypto.PublicKey import RSA
    from Crypto.Cipher import PKCS1_v1_5
    from argparse import ArgumentParser
    import time
    
    parser = ArgumentParser(description="这是RSA解密程序.", epilog="你学废了吗？")
    parser.add_argument("-c", "--cipher", type=str, default=r"./cd", help="密文路径")
    parser.add_argument("-p", "--plain", type=str, default=r"ef", help="明文输出路径")
    parser.add_argument("--private", type=str, default=r"./private.pem", help="解密密钥路径")
    parser.add_argument("--cerlen", type=int, default=1024, help="证书key位数")
    args = parser.parse_args()
    
    with open(args.cipher, "rb") as f:
        Cipher_text = f.read()
    
    """
    单次解密长度
    1024bit的证书用128，2048bit证书用256位
    """
    rsakey = RSA.importKey(open(args.private).read())
    cipher = PKCS1_v1_5.new(rsakey)
    # Plaintext = cipher.decrypt(b64decode(Cipher_text), "解密失败")
    Plaintext_ = []
    length = int(args.cerlen / 8)
    group = len(Cipher_text) // length + 1
    process_bar_len = 20
    start = time.perf_counter()
    for i in range(0, len(Cipher_text), length):
        Plaintext_.append(cipher.decrypt(Cipher_text[i:i + length], "解密失败"))
        # print("一共",group,"段，第",i//length,"段完成")
        dur = time.perf_counter() - start
        count = i // length + 2
        finished = count / group  # 完成的百分比
        print("\rdecryption progress:", "{}/{}={:^3.0f}% ◎{:.3f}s".format(count, group, finished * 100, dur),
              "★" * (int(process_bar_len * finished)) + "☆" * (int(process_bar_len * (1 - finished))), end="")
    Plaintext = b""
    for item in Plaintext_:
        Plaintext += item
    
    with open(args.plain, "wb") as f:
        f.write(Plaintext)
    print("\n" + args.cipher + " ■ Decryption Done...")
    print("Output:", args.plain)

命令行运行实例：

Z:\temp>python encryption.py -p plain.txt -c cipher.xyz
    encryption progress: 21/21 =100% ~0.087s ★★★★★★★★★★★★★★★★★★★★
    plain.txt ■ Encryption Done...
    Output: cipher.xyz
    
    Z:\temp>python decryption.py -c cipher.xyz -p plain_.txt
    decryption progress: 22/22=100% ◎0.624s ★★★★★★★★★★★★★★★★★★★★
    cipher.xyz ■ Decryption Done...
    Output: plain_.txt