Java AES / ECB / pkcs5padding encryption conversion Python 3

java AES/ECB/PKCS5padding encryption transformation Python

Be careful ： encryption 128 position AES The encryption mode is ECB To encrypt , Use after encryption Base64 transcoding .

Recently with java Project docking encountered AES encryption algorithm ,java The code has SecureRandom.getInstance("SHA1PRNG"); convert to Python

AES encryption

 Advanced encryption standard （Advanced Encryption Standard: AES） National Institute of standards and technology （NIST） stay 2001 The encryption specification of electronic data was established in .
 It is one of the most classical algorithms of symmetric encryption and decryption algorithm , It is a packet encryption standard , The size of each encryption block is 128 position , The allowed key length is 128、192 and 256 position . This is just an introduction ECB Encryption mode .

AES Encryption mode ：ECB/CBC/CTR/OFB/CFB
 fill ：pkcs5padding/pkcs7padding/zeropadding/iso10126/ansix923
 Data blocks ：128 position /192 position /256 position 
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ECB Pattern

ECB Mode as the simplest working mode , Group plaintext directly , Each group is encrypted separately , Each group is independent and irrelevant

Java Default encryption demo

Java Default AES The encryption mode is "AES/ECB/PKCS5Padding".

java Code display

package com.qzd.hit.util;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class Demo {

	/*** main * @author qizai * data: params * encStr: Here, the length of the key must be a multiple of 16 */
	public static void main(String[] args) throws Exception {
		// Encrypt Data
        String key = "ROcb6JybnKILLOlO"; // Secret Key length must be (16 24 32)
		String data = "[\"123456789\"]"; // Content to be encrypted
		String encStr = encrypt(data, key);  // Content to be decrypted
		System.out.println(encStr); //Encrypted data: w6oijM0xddQrItnH3UybLQ==
		// Decrypt Data
		String decStr = decrypt(encStr, key);
		System.out.println(decStr); //Decrypted data: ["123456789"]
	}

	public static String encrypt(String content, String password) {
		if (StringUtils.isEmpty(content) || StringUtils.isEmpty(password)) {
			System.out.println("AES encryption params is null");
			return null;
		}
		try {
			// Create cipher
			Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
			byte[] byteContent = content.getBytes("UTF-8");
			// Initialize as cryptographic cipher
			cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));
			byte[] encryptByte = cipher.doFinal(byteContent);
			return org.apache.commons.codec.binary.Base64.encodeBase64String(encryptByte);
		} catch (Exception e) {
			System.out.println("AES encryption operation has exception,content:{},password:{}", content, password, e);
		}
		return null;
	}

	public static String decrypt(String encryptContent, String password) throws Exception {
		if (StringUtils.isEmpty(encryptContent) || StringUtils.isEmpty(password)) {
			System.out.println("AES The request parameter is null");
			return null;
		}
		Cipher cipher = null;
		cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
		// Set to decryption mode
		cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));
		// Perform decryption operation
		byte[] result = cipher.doFinal(org.apache.commons.codec.binary.Base64.decodeBase64(encryptContent));
		return new String(result, "UTF-8");
	}

	private static SecretKeySpec getSecretKey(final String password) throws NoSuchAlgorithmException {
		// Generates the generator for the specified algorithm key
		KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
		SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
		random.setSeed(password.getBytes());
		keyGenerator.init(128, random);
		// Grnerate Key
		SecretKey secretKey = keyGenerator.generateKey();
		// Key converted to AES
		return new SecretKeySpec(secretKey.getEncoded(), "AES");
	}
}
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Encryption precautions :

KeyGenerator keyGenerator = KeyGenerator.getInstance("AES"); // Generates the generator for the specified algorithm key
SecureRandom random = SecureRandom.getInstance("SHA1PRNG"); // SHA1PRNG Random number algorithm
random.setSeed(password.getBytes());
keyGenerator.init(128, random);
SecretKey secretKey = keyGenerator.generateKey();
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Python Realization AES/ECB/PKCS5padding

install AES Correlation Library (window Next )

pip install pycryptodome
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Linux Lower installation

pip install pycrypto
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Relevant code implementation steps

import base64
import hashlib

import requests
from Crypto.Cipher import AES as _AES


class AES:

    def __init__(self, key: str):
        """Init aes object used by encrypt or decrypt. AES/ECB/PKCS5Padding same as aes in java default. """

        self.aes = _AES.new(self.get_sha1prng_key(key), _AES.MODE_ECB)

 @staticmethod
    def get_sha1prng_key(key: str) -> bytes:
        """encrypt key with SHA1PRNG. same as java AES crypto key generator SHA1PRNG. SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG" ); secureRandom.setSeed(decryptKey.getBytes()); keygen.init(128, secureRandom); :param string key: original key. :return bytes: encrypt key with SHA1PRNG, 128 bits or 16 long bytes. """

        signature: bytes = hashlib.sha1(key.encode()).digest()
        signature: bytes = hashlib.sha1(signature).digest()
        return signature[:16]

 @staticmethod
    def padding(s: str) -> str:
        """Padding PKCS5"""

        pad_num: int = 16 - len(s) % 16
        return s + pad_num * chr(pad_num)

 @staticmethod
    def unpadding(s):
        """Unpadding PKCS5"""

        padding_num: int = ord(s[-1])
        return s[: -padding_num]

    def encrypt_to_bytes(self, content_str):
        """From string encrypt to bytes ciphertext. """

        content_bytes = self.padding(content_str).encode()
        ciphertext_bytes = self.aes.encrypt(content_bytes)
        return ciphertext_bytes

    def encrypt_to_base64(self, content_str):
        """From string encrypt to base64 ciphertext. """

        ciphertext_bytes = self.encrypt_to_bytes(content_str)
        ciphertext_bs64 = base64.b64encode(ciphertext_bytes).decode()
        return ciphertext_bs64

    def decrypt_from_bytes(self, ciphertext_bytes):
        """From bytes ciphertext decrypt to string. """

        content_bytes = self.aes.decrypt(ciphertext_bytes)
        content_str = self.unpadding(content_bytes.decode())
        return content_str

    def decrypt_from_base64(self, ciphertext_bs64):
        """From base64 ciphertext decrypt to string. """

        ciphertext_bytes = base64.b64decode(ciphertext_bs64)
        content_str = self.decrypt_from_bytes(ciphertext_bytes)
        return content_str


def encrypt_to_bytes(content_str, encrypt_key: str):
    """From string encrypt to bytes ciphertext. """

    aes: AES = AES(encrypt_key)
    ciphertext_bytes = aes.encrypt_to_bytes(content_str)
    return ciphertext_bytes


def encrypt_to_base64(content_str, encrypt_key: str) -> str:
    """From string encrypt to base64 ciphertext. """

    aes: AES = AES(encrypt_key)
    ciphertext_bs64 = aes.encrypt_to_base64(content_str)
    return ciphertext_bs64


def decrypt_from_bytes(ciphertext_bytes, decrypt_key: str) -> str:
    """From bytes ciphertext decrypt to string. """

    aes: AES = AES(decrypt_key)
    content_str = aes.decrypt_from_bytes(ciphertext_bytes)
    return content_str


def decrypt_from_base64(ciphertext_bs64, decrypt_key: str) -> str:
    """From base64 ciphertext decrypt to string. """

    aes: AES = AES(decrypt_key)
    content_str = aes.decrypt_from_base64(ciphertext_bs64)
    return content_str


if __name__ == "__main__":
    key = "iC6qfFyiza8aq"
    encrypt_str_data = "[\"13811111111\"]"
    et = encrypt_to_base64(encrypt_str_data, key)
    print(" Encrypted data : ", et)
    ret = decrypt_from_base64(et, key)
    print(" Decrypted data : ", ret)

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Key code

This method realizes the right of key Transformation ,java Content of key encryption code in , Return here as 16 Base string .

 @staticmethod
    def get_sha1prng_key(key: str) -> bytes:
        """encrypt key with SHA1PRNG. same as java AES crypto key generator SHA1PRNG. SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG" ); secureRandom.setSeed(decryptKey.getBytes()); keygen.init(128, secureRandom); :param string key: original key. :return bytes: encrypt key with SHA1PRNG, 128 bits or 16 long bytes. """

        signature: bytes = hashlib.sha1(key.encode()).digest()
        signature: bytes = hashlib.sha1(signature).digest()
        return signature[:16]
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Simple version

import base64
import hashlib

from Crypto.Cipher import AES

SECRET_KEY = 'iC6qfFyiza8aq'  #  secret key 


class AesEncrypt(object):
    def __init__(self):
        self.key = self.getKey(SECRET_KEY)
        self.mode = AES.MODE_ECB

    def pading(self, text):
        """ Processing of encrypted characters """
        return text + (len(self.key) - len(text) % len(self.key)) * chr(len(self.key) - len(text) % len(self.key))

    def unpading(self, text):
        """ Processing of decrypted characters """
        return text[0:-ord(text[-1:])]

    def getKey(self, key):
        """ Yes key To deal with ,key  The length of  16,24,32"""
        signature: bytes = hashlib.sha1(key.encode()).digest()
        signature: bytes = hashlib.sha1(signature).digest()
        return signature[:16]

    def encrypt(self, text):
        """ Encryption function """
        ecb_encrypt = AES.new(self.key, self.mode)  # ECB  Pattern 
        ecb_text = ecb_encrypt.encrypt(bytes(self.pading(text), encoding="utf8"))
        encrypt_string = base64.b64encode(ecb_text).decode()
        return encrypt_string

    def decrypt(self, text):
        """ Decryption function """
        decode = base64.b64decode(text)
        ecb_decrypt = AES.new(self.key, self.mode)  # ECB  Pattern 
        plain_text = ecb_decrypt.decrypt(decode)
        decrypt_string = self.unpading(plain_text).decode()
        return decrypt_string


if __name__ == '__main__':
    aes_encrypt = AesEncrypt()
    data = "[\"13811111111\"]"
    en = aes_encrypt.encrypt(data)
    print(" Encrypt data : ", en)
    dr = aes_encrypt.decrypt(en)
    print(" Decrypt data : ", dr)

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1. Yes key Conduct sha1prng encryption , It's in the text get_sha1prng_key Method , Get the encrypted ciphertext as AES Of key

2. determine AES Encryption method of ECB,CBC etc.  AES Encryption mode ：ECB/CBC/CTR/OFB/CFB

3. fill ,key And the original text can be filled ,NoPadding, No fill ,0 fill , also pkcs5padding, Not filling is not filling the content , Direct encryption , The code above implements \0 Filling and pkcs5padding .

4. Generally speaking, encrypted content is basically key The processing is different or the filling is wrong .

【 Reference resources SHA1 Algorithm 】