Method decrypt

impacket/dpapi.py:302–331

(self, key)

        return keyMaterial[:keylen]

    def decrypt(self, key):
        if self['HashAlgo'] == ALGORITHMS.CALG_HMAC.value:
            hashModule = SHA1
        else:
            hashModule = ALGORITHMS_DATA[self['HashAlgo']][1]

        prf = lambda p, s: HMAC.new(p, s, hashModule).digest()
        derivedBlob = self.deriveKey(key, self['Salt'],
                                    ALGORITHMS_DATA[self['CryptAlgo']][0] + ALGORITHMS_DATA[self['CryptAlgo']][3],
                                    count=self['MasterKeyIterationCount'], hashFunction=prf)

        cryptKey = derivedBlob[:ALGORITHMS_DATA[self['CryptAlgo']][0]]
        iv = derivedBlob[ALGORITHMS_DATA[self['CryptAlgo']][0]:][:ALGORITHMS_DATA[self['CryptAlgo']][3]]

        cipher = ALGORITHMS_DATA[self['CryptAlgo']][1].new(cryptKey, mode = ALGORITHMS_DATA[self['CryptAlgo']][2], iv = iv)
        cleartext = cipher.decrypt(self['data'])

        decryptedKey = cleartext[-64:]
        hmacSalt = cleartext[:16]
        hmac = cleartext[16:][:ALGORITHMS_DATA[self['HashAlgo']][0]]

        hmacKey = HMAC.new(key, hmacSalt, hashModule).digest()

        hmacCalculated = HMAC.new(hmacKey, decryptedKey, hashModule ).digest()

        if hmacCalculated[:ALGORITHMS_DATA[self['HashAlgo']][0]] == hmac:
            self.decryptedKey = decryptedKey
            return decryptedKey
        else:
            return None

class CredHist(Structure):
    structure = (