def encrypt(value, key):
# skip32 generates 4 bytes output from 4 bytes input
_encrypt = True
skip32.skip32(key, value, _encrypt)
# raw bytes aren't suitable for a Code 128 barcode though,
# so convert it to base58 encoding
# which is just some alphanumeric and numeric chars and is
# designed to be vaguely human. this takes our 4 bytes and turns it into 11ish bytes
encrypted_value = base64.encodebytes(value).decode('ascii')
# important note: because we are not an even multiple of 3 bytes, base64 needs to pad
# the resulting string with equals signs. we can strip them out knowing that our length is 4 bytes
# IF YOU CHANGE THE LENGTH OF THE ENCRYPTED DATA FROM 4 BYTES, THIS WILL NO LONGER WORK.
encrypted_value = encrypted_value.replace('==\n', '')
return encrypted_value
def decrypt(value, key):
# raw bytes aren't suitable for a Code 128 barcode though,
# so convert it to base64 encoding
# which is just some alphanumeric and numeric chars and is
# designed to be vaguely human. this takes our 4 bytes and turns it into 6ish bytes
# important note: because we are not an even multiple of 3 bytes, base64 needs to pad
# the resulting string with equals signs. we can strip them out knowing that our length is 4 bytes
# IF YOU CHANGE THE LENGTH OF THE ENCRYPTED DATA FROM 4 BYTES, THIS WILL NO LONGER WORK.
value += '==\n'
decoded = base64.decodebytes(value.encode('ascii'))
# skip32 generates 4 bytes output from 4 bytes input
_encrypt = False
decrytped = bytearray(decoded)
skip32.skip32(key, decrytped, _encrypt)
return decrytped
