41 lines
1.1 KiB
Python
41 lines
1.1 KiB
Python
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import Crypto.Random
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from Crypto.Cipher import AES
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import hashlib
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# salt size in bytes
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SALT_SIZE = 16
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# number of iterations in the key generation
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NUMBER_OF_ITERATIONS = 20
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# the size multiple required for AES
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AES_MULTIPLE = 16
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def generate_key(password, salt, iterations):
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assert iterations > 0
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key = str.encode(password) + salt
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for i in range(iterations):
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key = hashlib.sha256(key).digest()
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return key
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def pad_text(text, multiple):
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return (text) + (chr((multiple - (len(text) % multiple))) * ((multiple - (len(text) % multiple))))
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def unpad_text(padded_text):
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return padded_text.decode('utf-8')[:-ord(padded_text.decode('utf-8')[-1])]
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def encrypt(plaintext, contract_id):
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salt = Crypto.Random.get_random_bytes(SALT_SIZE)
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return salt + (AES.new((generate_key(contract_id, salt, NUMBER_OF_ITERATIONS)), AES.MODE_ECB).encrypt(
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(pad_text(plaintext, AES_MULTIPLE))))
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def decrypt(ciphertext, contract_id):
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salt = ciphertext[0:SALT_SIZE]
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return unpad_text(
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AES.new((generate_key(contract_id, salt, NUMBER_OF_ITERATIONS)), AES.MODE_ECB).decrypt(ciphertext[SALT_SIZE:]))
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