Wie entschlüssele ich eine mit AES Bounty Castle codierte Zip-Datei in Python? ⇐ Python

[Guest]

Mein Teamkollege hat Kotlin-Code geschrieben, um ZIP-Dateien von der Android-Seite mit AES BC zu verschlüsseln, und ich versuche, ihn zu entschlüsseln. Aber es passiert nicht. Ich muss clientseitigen Python-Code schreiben, um diese Dateien zu entschlüsseln
Dies ist der Kotlin-Code

Code: Select all

import android.util.Base64
import android.util.Log
import java.io.BufferedInputStream
import java.io.BufferedOutputStream
import java.io.File
import java.io.FileInputStream
import java.io.FileOutputStream
import java.security.SecureRandom
import javax.crypto.Cipher
import javax.crypto.KeyGenerator
import javax.crypto.SecretKey
import javax.crypto.spec.IvParameterSpec
import javax.crypto.spec.SecretKeySpec
object AESEncryption {
fun generateSecretKey(): SecretKey {
val secureRandom = SecureRandom()
val keyGenerator = KeyGenerator.getInstance("AES")
//generate a key with secure random
keyGenerator?.init(256, secureRandom)
val key = keyGenerator.generateKey()
val secretKeyBase64 = Base64.encodeToString(key.encoded, Base64.NO_WRAP)
Log.e("AES KEY", "Generated AES key: $secretKeyBase64")
return key
}

fun readFile(filePath: String): ByteArray {
val file = File(filePath)
val fileContents = file.readBytes()
val inputBuffer = BufferedInputStream(
FileInputStream(file)
)

inputBuffer.read(fileContents)
inputBuffer.close()

return fileContents
}

fun saveFile(fileData: ByteArray, path: String) {
val file = File(path)
val bos = BufferedOutputStream(FileOutputStream(file, false))
bos.write(fileData)
bos.flush()
bos.close()
}

fun encrypt(yourKey: SecretKey, fileData: ByteArray): ByteArray {
val data = yourKey.getEncoded()
val skeySpec = SecretKeySpec(data, 0, data.size, "AES")
val cipher = Cipher.getInstance("AES", "BC")
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, IvParameterSpec(ByteArray(cipher.getBlockSize())))
return cipher.doFinal(fileData)
}

fun encryptDownloadedFile(filePath: String, secretKey: SecretKey) {
try {
val fileData = readFile(filePath)

//get secret key
//encrypt file
val encodedData = encrypt(secretKey, fileData)

saveFile(encodedData, "$filePath")

} catch (e: Exception) {
e.message?.let { Log.d("AEC", it) }
}
}

fun getSecretKey(): SecretKey{
val secretKeyEncoded = "key is here"
val decodedKey = Base64.decode(secretKeyEncoded, Base64.NO_WRAP)
val secretKey = SecretKeySpec(decodedKey, 0, decodedKey.size, "AES")
return secretKey
}

fun decrypt(yourKey: SecretKey, fileData: ByteArray): ByteArray {
val decrypted: ByteArray
val cipher = Cipher.getInstance("AES", "BC")
cipher.init(Cipher.DECRYPT_MODE, yourKey, IvParameterSpec(ByteArray(cipher.blockSize)))
decrypted = cipher.doFinal(fileData)
return decrypted
}

fun decryptEncryptedFile(filePath:  String) {
val fileData = readFile(filePath)
val secretKey = getSecretKey()
val decodedData = decrypt(secretKey, fileData)
saveFile(decodedData, "$filePath")
}
}

und das ist mein Python-Code

Code: Select all

from Crypto.Cipher import AES
import base64

def get_secret_key():
# This is the same key used in the Android code
secret_key_encoded = "7same key"
decoded_key = base64.b64decode(secret_key_encoded)
return decoded_key

def decrypt_file(input_file_path, output_file_path=None):
try:
# If no output path specified, create one by removing .encrypted extension if present
if output_file_path is None:
output_file_path = input_file_path.replace('.encrypted', '')
if output_file_path == input_file_path:
output_file_path = input_file_path.replace('.zip', '_decrypted.zip')

# Read the encrypted file
with open(input_file_path, 'rb') as file:
encrypted_data = file.read()

# Get the secret key
key = get_secret_key()

# Create cipher object and decrypt the data
cipher = AES.new(key, AES.MODE_CBC, iv=bytes(16))  # 16 bytes of zeros as IV
decrypted_data = cipher.decrypt(encrypted_data)

padding_length = decrypted_data[-1]
decrypted_data = decrypted_data[:-padding_length]

# Write the decrypted data to output file
with open(output_file_path, 'wb') as file:
file.write(decrypted_data)

print(f"File decrypted successfully: {output_file_path}")
return True

except Exception as e:
print(f"Error during decryption: {str(e)}")
return False

# Example usage
if __name__ == "__main__":
# Example usage
encrypted_file_path = "com.android.settings_1736318346774.zip"
decrypt_file(encrypted_file_path)

Mit diesem Code wird die ZIP-Datei generiert, kann aber nicht entpackt werden