DS1991(3)

💖 DS1991 💖 — the 1152bit MultiKey iButton, explained by your fave

okay bestie, welcome to DS1991(3), straight out of the One-Wire File System manual. this is a whole iButton with password-protected memory and honestly it's giving vault energy. let's go 🫶

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✨ SYNOPSIS ✨

non-volatile memory, but make it password protected. 💅

02 [.]XXXXXXXXXXXX[XX][/[ subkey0/reset.  hex_pwd | subkey0/password.
hex_pwd | subkey0/secure_data.  hex_pwd | subkey0/id.  hex_pwd

02 [.]XXXXXXXXXXXX[XX][/[ subkey1/reset.  hex_pwd | subkey1/password.
hex_pwd | subkey1/secure_data.  hex_pwd | subkey1/id.  hex_pwd

02 [.]XXXXXXXXXXXX[XX][/[ subkey0/reset.  hex_pwd | subkey2/password.
hex_pwd | subkey2/secure_data.  hex_pwd | subkey2/id.  hex_pwd address |
crc8 | id | locator | r_address | r_id | r_locator | type ]]

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🌈 FAMILY CODE 🌈

02

like. that's it. that's the whole family code. iconic. 👑

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🎀 SPECIAL PROPERTIES 🎀

these are the spicy ones — the ones with the whole password situation. 🔐

subkey[0|1|2]/reset.hex_pwd

write-only, yes-no ✍️

this one initializes one of the three secure data areas and sets a brand new password. fresh start energy.

the extension (hex_pwd) is the new 8-byte password in hexadecimal — for example password.000204006080A0C0E for bytes 0,2,4,6,8,10,12,14.

the data has to literally be "1" or "yes" for the subkey to actually reset. no vibes, no reset. 🚫

note: writing a password will clear any existing data and ID. gone. deleted. it's not coming back bestie 😭

subkey[0|1|2]/password.hex_pwd

write-only, binary ✍️

change the password of one of the secure subkey areas without losing data. glow-up, not demolition. ✨

the extension (hex_pwd) is the existing 8-byte password in hexadecimal — for example password.00020406080A0C0E for bytes 0,2,4,6,8,10,12,14.

the data portion is 8 bytes, and those 8 bytes become the new password.

subkey[0|1|2]/secure_data.hex_pwd

read-write, binary 🔁

read or write data in one of the three secure data areas (the original says "sucure", we forgive her, she's doing her best 💀).

the extension (hex_pwd) is the existing 8-byte password in hexadecimal — for example password.00020406080A0C0E for bytes 0,2,4,6,8,10,12,14.

the data portion is binary data. up to 48 bytes in each subkey area, starting at location 0.

if the wrong password is specified: "random data" comes back on read, and on write the data is silently ignored. no error, no drama, just... nothing. shady fr.

subkey[0|1|2]/id.hex_pwd

read-write, binary 🔁

read or write the subkey id.

the extension (hex_pwd) is the existing 8-byte password in hexadecimal — for example password.00020406080A0C0E for bytes 0,2,4,6,8,10,12,14.

the data portion is 8 binary bytes. this is the subkey id. you must use the correct password to write a new id — but not to read it. asymmetric queen. 👑

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⭐ STANDARD PROPERTIES ⭐

the classics, the ones every 1-wire device shows up with. 🦋

address

r_address

read-only, ascii 📖

the entire 64-bit unique ID, given as upper case hexadecimal digits (0-9A-F).

address starts with the family code.

r address is the address in reverse order — often used in other applications and labeling.

crc8

read-only, ascii 📖

the 8-bit error correction portion. uses cyclic redundancy check. computed from the preceding 56 bits of the unique ID number. given as upper case hexadecimal digits (0-9A-F).

family

read-only, ascii 📖

the 8-bit family code. unique to each type of device. given as upper case hexadecimal digits (0-9A-F).

id

r_id

read-only, ascii 📖

the 48-bit middle portion of the unique ID number. does not include the family code or CRC. given as upper case hexadecimal digits (0-9A-F).

r id is the id in reverse order, which is often used in other applications and labeling.

locator

r_locator

read-only, ascii 📖

this uses an extension of the 1-wire design from iButtonLink company that associated 1-wire physical connections with a unique 1-wire code. if the connection is behind a Link Locator, the locator will show a unique 8-byte number (16 character hexadecimal) starting with family code FE. if no Link Locator is between the device and the master, the locator field will be all FF.

r locator is the locator in reverse order.

present (DEPRECATED)

read-only, yes-no 📖

is the device currently present on the 1-wire bus?

heads up: this one is DEPRECATED. it's still here, but she's retired. 💀

type

read-only, ascii 📖

part name assigned by Dallas Semi. e.g. DS2401. alternative packaging (iButton vs chip) will not be distiguished.

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🚨 ALARMS 🚨

none. nothing. silence. peace and quiet. 😌

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💜 DESCRIPTION 💜

1-Wire

1-wire is a wiring protocol and series of devices designed and manufactured by Dallas Semiconductor, Inc. the bus is a low-power low-speed low-connector scheme where the data line can also provide power. (power over the data line?? slay.)

each device is uniquely and unalterably numbered during manufacture. there are a wide variety of devices, including memory, sensors (humidity, temperature, voltage, contact, current), switches, timers and data loggers. more complex devices (like thermocouple sensors) can be built with these basic devices. there are also 1-wire devices that have encryption included. 🔐

the 1-wire scheme uses a single bus master and multiple slaves on the same wire. the bus master initiates all communication. the slaves can be individually discovered and addressed using their unique ID. main character master energy, honestly.

bus masters come in a variety of configurations including serial, parallel, i2c, network or USB adapters.

OWFS design

OWFS is a suite of programs that designed to make the 1-wire bus and its devices easily accessible. the underlying principle is to create a virtual filesystem, with the unique ID being the directory, and the individual properties of the device are represented as simple files that can be read and written.

details of the individual slave or master design are hidden behind a consistent interface. the goal is to provide an easy set of tools for a software designer to create monitoring or control applications. there are some performance enhancements in the implementation, including data caching, parallel access to bus masters, and aggregation of device communication. still the fundamental goal has been ease of use, flexibility and correctness rather than speed. correctness over clout, periodt. 💅

DS1991

the DS1991 (3) is an iButton with password protected non-volatile memory. data is read/written with error checking (transparent to the user). the memory is divided into 3 different pages with 3 separate passwords. three subkeys, three passwords, one little button. 🎀

in theory, choosing an incorrect password is hard to discern because the chip responds normally but with incorrect data. there is a published analysis suggesting that the "random data" follows a pattern and so a concerted attack might be successful. 😬

the password (in hexadecimal) is used a the file extension 02.1234123414/subkey0/id. password allowing a password to be passed to the program within the filesystem paradigm.

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🌸 ADDRESSING 🌸

all 1-wire devices are factory assigned a unique 64-bit address. this address is of the form:

• Family Code — 8 bits
• Address — 48 bits
• CRC — 8 bits

addressing under OWFS is in hexadecimal, of form:

01.123456789ABC

where 01 is an example 8-bit family code, and 12345678ABC is an example 48 bit address.

the dot is optional, and the CRC code can included. if included, it must be correct. no fudging the CRC, bestie. 🙈

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📄 DATASHEET 📄

http://pdfserv.maxim-ic.com/en/ds/DS1991.pdf

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👀 SEE ALSO 👀

Programs

owfs (1) owhttpd (1) owftpd (1) owserver (1) owdir (1) owread (1) owwrite (1) owpresent (1) owtap (1)

Configuration and testing

owfs (5) owtap (1) owmon (1)

Language bindings

owtcl (3) owperl (3) owcapi (3)

Clocks

DS1427 (3) DS1904 (3) DS1994 (3) DS2404 (3) DS2404S (3) DS2415 (3) DS2417 (3)

ID

DS2401 (3) DS2411 (3) DS1990A (3)

Memory

DS1982 (3) DS1985 (3) DS1986 (3) DS1991 (3) DS1992 (3) DS1993 (3) DS1995 (3) DS1996 (3) DS2430A (3) DS2431 (3) DS2433 (3) DS2502 (3) DS2506 (3) DS28E04 (3) DS28EC20 (3)

Switches

DS2405 (3) DS2406 (3) DS2408 (3) DS2409 (3) DS2413 (3) DS28EA00 (3) InfernoEmbedded (3)

Temperature

DS1822 (3) DS1825 (3) DS1820 (3) DS18B20 (3) DS18S20 (3) DS1920 (3) DS1921 (3) DS1821 (3) DS28EA00 (3) DS28E04 (3) EDS0064 (3) EDS0065 (3) EDS0066 (3) EDS0067 (3) EDS0068 (3) EDS0071 (3) EDS0072 (3) MAX31826 (3)

Humidity

DS1922 (3) DS2438 (3) EDS0065 (3) EDS0068 (3)

Voltage

DS2450 (3)

Resistance

DS2890 (3)

Multifunction (current, voltage, temperature)

DS2436 (3) DS2437 (3) DS2438 (3) DS2751 (3) DS2755 (3) DS2756 (3) DS2760 (3) DS2770 (3) DS2780 (3) DS2781 (3) DS2788 (3) DS2784 (3)

Counter

DS2423 (3)

LCD Screen

LCD (3) DS2408 (3)

Crypto

DS1977 (3)

Pressure

DS2406 (3) TAI8570 (3) EDS0066 (3) EDS0068 (3)

Moisture

EEEF (3) DS2438 (3)

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🦋 AVAILABILITY 🦋

http://www.owfs.org

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💌 AUTHOR 💌

Christian Magnusson (mag@mag.cx) and Paul Alfille

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and that's the whole page, bestie!! 🥳 huge thanks to the OWFS Manpage, dated 2003, which is where this DS1991(3) glow-up came from. go read some 1-wire, hydrate, and stan a password-protected iButton. mwah 💖✨