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August 5, 2023 · 3 min

Shamir's Secret Sharing Backup (SLIP39)

What is a Shamir Backup?

As the popularity of cryptocurrencies continues to grow, so does the need for secure storage solutions for private keys and seed phrases. One such solution is the Shamir Backup, which uses a technique called Shamir's Secret Sharing to split a seed phrase into multiple pieces, allowing for secure storage across multiple locations.

The History of Shamir's Secret Sharing

Shamir's Secret Sharing System (SSSS) is a cryptographic algorithm developed by Adi Shamir in 1979. The algorithm allows for the sharing of a secret among a group of individuals, without any one individual having access to the entire secret.

The algorithm works by breaking the secret into multiple pieces, called shares, and distributing them among the group. The secret can then be reconstructed by combining a minimum number of shares, known as the threshold.

Implementation in Crypto Hardware Wallets

In the world of cryptocurrencies, seed phrases are used to generate private keys, which are necessary for accessing and managing funds. Losing a single seed phrase can result in the loss of (access to the) funds, which is why secure storage is essential.

Many crypto hardware wallets, such as the Trezor Safe 3, Safe 5, Model T, and Keystone, now offer Shamir Backup as a feature. These backups are also known as Single-share or Multi-share backups. This allows users to "split" their seed phrase into multiple shares, that can be stored in different physical locations, such as a safe or a safety deposit box.

How It Works

To use Shamir Backup, a user first selects the number of shares they want to create and the threshold required to reconstruct the seed phrase. For example, a user may choose to create five shares, with a threshold of three. This means that a user can lose 2 shares and still recover the wallet with the 3 remaining shares.

The Shamir's Secret Sharing algorithm then generates the shares, which are essentially random strings of characters. Each share is a unique mnemonic recovery phrase and contains a string of either 20 or 33 words. The user can then store these shares in different physical locations, such as a safe, a safety deposit box, or with trusted friends or family members.

The words from the Shamir's Secret Sharing System for crypto wallets come from the official and open-source SLIP-39 wordlist. This word list contains 1024 commonly used words, that are easy to store. Please keep in mind there are 2 different protocols, BIP-39 and SLIP-39. They both have different word lists, but some words from the BIP-39 wordlist can be found in the SLIP-39 wordlist and vice versa.

To reconstruct the seed phrase, the user must have a minimum number of shares, known as the threshold. In the example above, the user would need at least three of the five shares to reconstruct the seed phrase.

Overall, Shamir Backup is a powerful tool for ensuring the secure storage of seed phrases and private keys. By using Shamir's Secret Sharing algorithm, users can split their seed phrase into multiple shares, allowing for secure storage across multiple physical locations. As the crypto scene continues to grow, solutions like Shamir Backup will become increasingly important for ensuring the security of digital assets.

The Cryptotag Odin was still legible after being exposed to fire, acid, and extreme pressure. Odin received a Triple A status in the Jameson Lopp tests.

Cryptotag products have been extensively tested under extreme conditions. Since Cryptotag products are made out of high-quality titanium, the products can withstand fires and heat up to 1665°C / 3029 °F. On top of that, Cryptotag products are bulletproof, water-resistant, acid-resistant (tested with muriatic acid), and can withstand the extreme pressure of a 20-ton hydraulic press used to deform the device, after which the data is checked for readability. In all cases, Cryptotag products were still legible and no data loss occurred.

Cryptotag Grading in the independent Jameson Lopp Metal Seed Phrase Backup tests. Cryptotag received the best possible rating.


All Cryptotag products have received a Triple A status in the independent Jameson Lopp test. Check out the Odin durability test by Jameson Lopp.

The SLIP-39 wordlist

. It is an open-source and industry-standard word list and can be found on Github or on educational websites or websites of companies that provide relevant software or hardware solutions for the SLIP-39 protocol.

The SLIP-39 protocol word list has been carefully composed with the following keynotes:

  • The wordlist is alphabetically sorted.
  • No word is shorter than 4 letters.
  • No word is longer than 8 letters.
  • All words begin with a unique 4-letter prefix.
  • The wordlist contains only common English words (+ the word "satoshi").
  • The minimum Damerau-Levenshtein distance between any two words is at least 2.
  • The similarity between the pronunciation of any two words has been minimized.

    The SLIP-39 words and corresponding numbers can be found in this list:
0001	academic
0002	acid
0003	acne
0004	acquire
0005	acrobat
0006	activity
0007	actress
0008	adapt
0009	adequate
0010	adjust
0011	admit
0012	adorn
0013	adult
0014	advance
0015	advocate
0016	afraid
0017	again
0018	agency
0019	agree
0020	aide
0021	aircraft
0022	airline
0023	airport
0024	ajar
0025	alarm
0026	album
0027	alcohol
0028	alien
0029	alive
0030	alpha
0031	already
0032	alto
0033	aluminum
0034	always
0035	amazing
0036	ambition
0037	amount
0038	amuse
0039	analysis
0040	anatomy
0041	ancestor
0042	ancient
0043	angel
0044	angry
0045	animal
0046	answer
0047	antenna
0048	anxiety
0049	apart
0050	aquatic
0051	arcade
0052	arena
0053	argue
0054	armed
0055	artist
0056	artwork
0057	aspect
0058	auction
0059	august
0060	aunt
0061	average
0062	aviation
0063	avoid
0064	award
0065	away
0066	axis
0067	axle
0068	beam
0069	beard
0070	beaver
0071	become
0072	bedroom
0073	behavior
0074	being
0075	believe
0076	belong
0077	benefit
0078	best
0079	beyond
0080	bike
0081	biology
0082	birthday
0083	bishop
0084	black
0085	blanket
0086	blessing
0087	blimp
0088	blind
0089	blue
0090	body
0091	bolt
0092	boring
0093	born
0094	both
0095	boundary
0096	bracelet
0097	branch
0098	brave
0099	breathe
0100	briefing
0101	broken
0102	brother
0103	browser
0104	bucket
0105	budget
0106	building
0107	bulb
0108	bulge
0109	bumpy
0110	bundle
0111	burden
0112	burning
0113	busy
0114	buyer
0115	cage
0116	calcium
0117	camera
0118	campus
0119	canyon
0120	capacity
0121	capital
0122	capture
0123	carbon
0124	cards
0125	careful
0126	cargo
0127	carpet
0128	carve
0129	category
0130	cause
0131	ceiling
0132	center
0133	ceramic
0134	champion
0135	change
0136	charity
0137	check
0138	chemical
0139	chest
0140	chew
0141	chubby
0142	cinema
0143	civil
0144	class
0145	clay
0146	cleanup
0147	client
0148	climate
0149	clinic
0150	clock
0151	clogs
0152	closet
0153	clothes
0154	club
0155	cluster
0156	coal
0157	coastal
0158	coding
0159	column
0160	company
0161	corner
0162	costume
0163	counter
0164	course
0165	cover
0166	cowboy
0167	cradle
0168	craft
0169	crazy
0170	credit
0171	cricket
0172	criminal
0173	crisis
0174	critical
0175	crowd
0176	crucial
0177	crunch
0178	crush
0179	crystal
0180	cubic
0181	cultural
0182	curious
0183	curly
0184	custody
0185	cylinder
0186	daisy
0187	damage
0188	dance
0189	darkness
0190	database
0191	daughter
0192	deadline
0193	deal
0194	debris
0195	debut
0196	decent
0197	decision
0198	declare
0199	decorate
0200	decrease
0201	deliver
0202	demand
0203	density
0204	deny
0205	depart
0206	depend
0207	depict
0208	deploy
0209	describe
0210	desert
0211	desire
0212	desktop
0213	destroy
0214	detailed
0215	detect
0216	device
0217	devote
0218	diagnose
0219	dictate
0220	diet
0221	dilemma
0222	diminish
0223	dining
0224	diploma
0225	disaster
0226	discuss
0227	disease
0228	dish
0229	dismiss
0230	display
0231	distance
0232	dive
0233	divorce
0234	document
0235	domain
0236	domestic
0237	dominant
0238	dough
0239	downtown
0240	dragon
0241	dramatic
0242	dream
0243	dress
0244	drift
0245	drink
0246	drove
0247	drug
0248	dryer
0249	duckling
0250	duke
0251	duration
0252	dwarf
0253	dynamic
0254	early
0255	earth
0256	easel
0257	easy
0258	echo
0259	eclipse
0260	ecology
0261	edge
0262	editor
0263	educate
0264	either
0265	elbow
0266	elder
0267	election
0268	elegant
0269	element
0270	elephant
0271	elevator
0272	elite
0273	else
0274	email
0275	emerald
0276	emission
0277	emperor
0278	emphasis
0279	employer
0280	empty
0281	ending
0282	endless
0283	endorse
0284	enemy
0285	energy
0286	enforce
0287	engage
0288	enjoy
0289	enlarge
0290	entrance
0291	envelope
0292	envy
0293	epidemic
0294	episode
0295	equation
0296	equip
0297	eraser
0298	erode
0299	escape
0300	estate
0301	estimate
0302	evaluate
0303	evening
0304	evidence
0305	evil
0306	evoke
0307	exact
0308	example
0309	exceed
0310	exchange
0311	exclude
0312	excuse
0313	execute
0314	exercise
0315	exhaust
0316	exotic
0317	expand
0318	expect
0319	explain
0320	express
0321	extend
0322	extra
0323	eyebrow
0324	facility
0325	fact
0326	failure
0327	faint
0328	fake
0329	false
0330	family
0331	famous
0332	fancy
0333	fangs
0334	fantasy
0335	fatal
0336	fatigue
0337	favorite
0338	fawn
0339	fiber
0340	fiction
0341	filter
0342	finance
0343	findings
0344	finger
0345	firefly
0346	firm
0347	fiscal
0348	fishing
0349	fitness
0350	flame
0351	flash
0352	flavor
0353	flea
0354	flexible
0355	flip
0356	float
0357	floral
0358	fluff
0359	focus
0360	forbid
0361	force
0362	forecast
0363	forget
0364	formal
0365	fortune
0366	forward
0367	founder
0368	fraction
0369	fragment
0370	frequent
0371	freshman
0372	friar
0373	fridge
0374	friendly
0375	frost
0376	froth
0377	frozen
0378	fumes
0379	funding
0380	furl
0381	fused
0382	galaxy
0383	game
0384	garbage
0385	garden
0386	garlic
0387	gasoline
0388	gather
0389	general
0390	genius
0391	genre
0392	genuine
0393	geology
0394	gesture
0395	glad
0396	glance
0397	glasses
0398	glen
0399	glimpse
0400	goat
0401	golden
0402	graduate
0403	grant
0404	grasp
0405	gravity
0406	gray
0407	greatest
0408	grief
0409	grill
0410	grin
0411	grocery
0412	gross
0413	group
0414	grownup
0415	grumpy
0416	guard
0417	guest
0418	guilt
0419	guitar
0420	gums
0421	hairy
0422	hamster
0423	hand
0424	hanger
0425	harvest
0426	have
0427	havoc
0428	hawk
0429	hazard
0430	headset
0431	health
0432	hearing
0433	heat
0434	helpful
0435	herald
0436	herd
0437	hesitate
0438	hobo
0439	holiday
0440	holy
0441	home
0442	hormone
0443	hospital
0444	hour
0445	huge
0446	human
0447	humidity
0448	hunting
0449	husband
0450	hush
0451	husky
0452	hybrid
0453	idea
0454	identify
0455	idle
0456	image
0457	impact
0458	imply
0459	improve
0460	impulse
0461	include
0462	income
0463	increase
0464	index
0465	indicate
0466	industry
0467	infant
0468	inform
0469	inherit
0470	injury
0471	inmate
0472	insect
0473	inside
0474	install
0475	intend
0476	intimate
0477	invasion
0478	involve
0479	iris
0480	island
0481	isolate
0482	item
0483	ivory
0484	jacket
0485	jerky
0486	jewelry
0487	join
0488	judicial
0489	juice
0490	jump
0491	junction
0492	junior
0493	junk
0494	jury
0495	justice
0496	kernel
0497	keyboard
0498	kidney
0499	kind
0500	kitchen
0501	knife
0502	knit
0503	laden
0504	ladle
0505	ladybug
0506	lair
0507	lamp
0508	language
0509	large
0510	laser
0511	laundry
0512	lawsuit
0513	leader
0514	leaf
0515	learn
0516	leaves
0517	lecture
0518	legal
0519	legend
0520	legs
0521	lend
0522	length
0523	level
0524	liberty
0525	library
0526	license
0527	lift
0528	likely
0529	lilac
0530	lily
0531	lips
0532	liquid
0533	listen
0534	literary
0535	living
0536	lizard
0537	loan
0538	lobe
0539	location
0540	losing
0541	loud
0542	loyalty
0543	luck
0544	lunar
0545	lunch
0546	lungs
0547	luxury
0548	lying
0549	lyrics
0550	machine
0551	magazine
0552	maiden
0553	mailman
0554	main
0555	makeup
0556	making
0557	mama
0558	manager
0559	mandate
0560	mansion
0561	manual
0562	marathon
0563	march
0564	market
0565	marvel
0566	mason
0567	material
0568	math
0569	maximum
0570	mayor
0571	meaning
0572	medal
0573	medical
0574	member
0575	memory
0576	mental
0577	merchant
0578	merit
0579	method
0580	metric
0581	midst
0582	mild
0583	military
0584	mineral
0585	minister
0586	miracle
0587	mixed
0588	mixture
0589	mobile
0590	modern
0591	modify
0592	moisture
0593	moment
0594	morning
0595	mortgage
0596	mother
0597	mountain
0598	mouse
0599	move
0600	much
0601	mule
0602	multiple
0603	muscle
0604	museum
0605	music
0606	mustang
0607	nail
0608	national
0609	necklace
0610	negative
0611	nervous
0612	network
0613	news
0614	nuclear
0615	numb
0616	numerous
0617	nylon
0618	oasis
0619	obesity
0620	object
0621	observe
0622	obtain
0623	ocean
0624	often
0625	olympic
0626	omit
0627	oral
0628	orange
0629	orbit
0630	order
0631	ordinary
0632	organize
0633	ounce
0634	oven
0635	overall
0636	owner
0637	paces
0638	pacific
0639	package
0640	paid
0641	painting
0642	pajamas
0643	pancake
0644	pants
0645	papa
0646	paper
0647	parcel
0648	parking
0649	party
0650	patent
0651	patrol
0652	payment
0653	payroll
0654	peaceful
0655	peanut
0656	peasant
0657	pecan
0658	penalty
0659	pencil
0660	percent
0661	perfect
0662	permit
0663	petition
0664	phantom
0665	pharmacy
0666	photo
0667	phrase
0668	physics
0669	pickup
0670	picture
0671	piece
0672	pile
0673	pink
0674	pipeline
0675	pistol
0676	pitch
0677	plains
0678	plan
0679	plastic
0680	platform
0681	playoff
0682	pleasure
0683	plot
0684	plunge
0685	practice
0686	prayer
0687	preach
0688	predator
0689	pregnant
0690	premium
0691	prepare
0692	presence
0693	prevent
0694	priest
0695	primary
0696	priority
0697	prisoner
0698	privacy
0699	prize
0700	problem
0701	process
0702	profile
0703	program
0704	promise
0705	prospect
0706	provide
0707	prune
0708	public
0709	pulse
0710	pumps
0711	punish
0712	puny
0713	pupal
0714	purchase
0715	purple
0716	python
0717	quantity
0718	quarter
0719	quick
0720	quiet
0721	race
0722	racism
0723	radar
0724	railroad
0725	rainbow
0726	raisin
0727	random
0728	ranked
0729	rapids
0730	raspy
0731	reaction
0732	realize
0733	rebound
0734	rebuild
0735	recall
0736	receiver
0737	recover
0738	regret
0739	regular
0740	reject
0741	relate
0742	remember
0743	remind
0744	remove
0745	render
0746	repair
0747	repeat
0748	replace
0749	require
0750	rescue
0751	research
0752	resident
0753	response
0754	result
0755	retailer
0756	retreat
0757	reunion
0758	revenue
0759	review
0760	reward
0761	rhyme
0762	rhythm
0763	rich
0764	rival
0765	river
0766	robin
0767	rocky
0768	romantic
0769	romp
0770	roster
0771	round
0772	royal
0773	ruin
0774	ruler
0775	rumor
0776	sack
0777	safari
0778	salary
0779	salon
0780	salt
0781	satisfy
0782	satoshi
0783	saver
0784	says
0785	scandal
0786	scared
0787	scatter
0788	scene
0789	scholar
0790	science
0791	scout
0792	scramble
0793	screw
0794	script
0795	scroll
0796	seafood
0797	season
0798	secret
0799	security
0800	segment
0801	senior
0802	shadow
0803	shaft
0804	shame
0805	shaped
0806	sharp
0807	shelter
0808	sheriff
0809	short
0810	should
0811	shrimp
0812	sidewalk
0813	silent
0814	silver
0815	similar
0816	simple
0817	single
0818	sister
0819	skin
0820	skunk
0821	slap
0822	slavery
0823	sled
0824	slice
0825	slim
0826	slow
0827	slush
0828	smart
0829	smear
0830	smell
0831	smirk
0832	smith
0833	smoking
0834	smug
0835	snake
0836	snapshot
0837	sniff
0838	society
0839	software
0840	soldier
0841	solution
0842	soul
0843	source
0844	space
0845	spark
0846	speak
0847	species
0848	spelling
0849	spend
0850	spew
0851	spider
0852	spill
0853	spine
0854	spirit
0855	spit
0856	spray
0857	sprinkle
0858	square
0859	squeeze
0860	stadium
0861	staff
0862	standard
0863	starting
0864	station
0865	stay
0866	steady
0867	step
0868	stick
0869	stilt
0870	story
0871	strategy
0872	strike
0873	style
0874	subject
0875	submit
0876	sugar
0877	suitable
0878	sunlight
0879	superior
0880	surface
0881	surprise
0882	survive
0883	sweater
0884	swimming
0885	swing
0886	switch
0887	symbolic
0888	sympathy
0889	syndrome
0890	system
0891	tackle
0892	tactics
0893	tadpole
0894	talent
0895	task
0896	taste
0897	taught
0898	taxi
0899	teacher
0900	teammate
0901	teaspoon
0902	temple
0903	tenant
0904	tendency
0905	tension
0906	terminal
0907	testify
0908	texture
0909	thank
0910	that
0911	theater
0912	theory
0913	therapy
0914	thorn
0915	threaten
0916	thumb
0917	thunder
0918	ticket
0919	tidy
0920	timber
0921	timely
0922	ting
0923	tofu
0924	together
0925	tolerate
0926	total
0927	toxic
0928	tracks
0929	traffic
0930	training
0931	transfer
0932	trash
0933	traveler
0934	treat
0935	trend
0936	trial
0937	tricycle
0938	trip
0939	triumph
0940	trouble
0941	true
0942	trust
0943	twice
0944	twin
0945	type
0946	typical
0947	ugly
0948	ultimate
0949	umbrella
0950	uncover
0951	undergo
0952	unfair
0953	unfold
0954	unhappy
0955	union
0956	universe
0957	unkind
0958	unknown
0959	unusual
0960	unwrap
0961	upgrade
0962	upstairs
0963	username
0964	usher
0965	usual
0966	valid
0967	valuable
0968	vampire
0969	vanish
0970	various
0971	vegan
0972	velvet
0973	venture
0974	verdict
0975	verify
0976	very
0977	veteran
0978	vexed
0979	victim
0980	video
0981	view
0982	vintage
0983	violence
0984	viral
0985	visitor
0986	visual
0987	vitamins
0988	vocal
0989	voice
0990	volume
0991	voter
0992	voting
0993	walnut
0994	warmth
0995	warn
0996	watch
0997	wavy
0998	wealthy
0999	weapon
1000	webcam
1001	welcome
1002	welfare
1003	western
1004	width
1005	wildlife
1006	window
1007	wine
1008	wireless
1009	wisdom
1010	withdraw
1011	wits
1012	wolf
1013	woman
1014	work
1015	worthy
1016	wrap
1017	wrist
1018	writing
1019	wrote
1020	year
1021	yelp
1022	yield
1023	yoga
1024	zero

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