+// Calculate CRC-8/Maxim checksum
+uint32_t CRC8Maxim(uint8_t *buff, size_t size);
+
+// Calculate CRC-4/Legic checksum
+uint32_t CRC4Legic(uint8_t *buff, size_t size);
+
+// Calculate CRC-8/Legic checksum
+uint32_t CRC8Legic(uint8_t *buff, size_t size);
+
+// Calculate CRC-16/Legic checksum
+// the initial_value is based on the previous legic_Crc8 of the UID.
+// ie: uidcrc = 0x78 then initial_value == 0x7878
+uint32_t CRC16Legic(uint8_t *buff, size_t size, uint8_t uidcrc);
+
+// test crc 16.
+uint32_t CRC16_DNP(uint8_t *buff, size_t size);
+uint32_t CRC16_CCITT(uint8_t *buff, size_t size);
+