# хэширование текстовых или байтовых данных
def gostHash(data, isText=True):
    hashedData = pycades.HashedData()
    hashedData.Algorithm = pycades.CADESCOM_HASH_ALGORITHM_CP_GOST_3411_2012_256
    hashedData.DataEncoding = pycades.CADESCOM_BASE64_TO_BINARY
    if isText:
        hashedData.Hash(base64.b64encode(data.encode("utf-8")).decode())
    else:
        hashedData.Hash(base64.b64encode(data).decode())
    hexHash = hashedData.Value
    byteHash = bytes.fromhex(hexHash)
    return base64.b64encode(byteHash).decode()

# само значение подписи.
# возвращать надо либо signature либо invert в зависимости от принимающей стороны
def signHash(cert, hashBase64):
    hashValue = base64.b64decode(hashBase64)
    hashValue = hashValue.hex()
    hashedData = pycades.HashedData()
    hashedData.Algorithm = pycades.CADESCOM_HASH_ALGORITHM_CP_GOST_3411_2012_256
    hashedData.DataEncoding = pycades.CADESCOM_BASE64_TO_BINARY
    hashedData.SetHashValue(hashValue)
    rawSign = pycades.RawSignature()
    signature = rawSign.SignHash(hashedData, cert)
    invert = bytearray(reversed(bytearray.fromhex(signature)))
    invert = base64.b64encode(invert).decode()
    signature = bytes.fromhex(signature)
    signature = base64.b64encode(signature).decode()
    # return signature
    return invert

signed_data = pycades.SignedData()
result = signed_data.VerifyCades(content, pycades.CADESCOM_CADES_BES)

    result = signed_data.VerifyCades(content, pycades.CADESCOM_CADES_T)
Exception: Internal error. (0x8009100E)

import os
import pycades
import base64


def decrypt(bas64):
    envelopeddata = pycades.EnvelopedData()
    envelopeddata.Decrypt(bas64)
    envelopeddata.ContentEncoding = pycades.CADESCOM_BASE64_TO_BINARY
    return base64.b64decode(envelopeddata.Content).decode()


def verify(_sign, cadesType=pycades.CADESCOM_CADES_BES, detached=False):
    signedData = pycades.SignedData()
    try:
        signedData.VerifyCades(_sign, cadesType, detached)
        return True
    except Exception as err:
        print('Verify fail')
        print(err)
        return False


def getContent(sign, cadesType=pycades.CADESCOM_CADES_BES):
    signedData = pycades.SignedData()
    signedData.VerifyCades(sign, cadesType, False)
    signedData.ContentEncoding = pycades.CADESCOM_BASE64_TO_BINARY
    return base64.b64decode(signedData.Content).decode()


signed_encoded_file = open(os.path.expanduser('~') + '/data.txt.sig.enc', 'r').read()

sign = decrypt(signed_encoded_file)

print(sign)
if verify(sign):
    print(getContent(sign))