passphrase.go

// Package crypto provides the crypto utils to the program.
package crypto

import (
	"crypto/rand"
	"encoding/binary"
	"fmt"
	"os"
	"runtime"
	"strings"

	"golang.org/x/term"
)


func PassphrasePromptForUnlock() (string, error) {
	pass, err := readPassphrase("Enter passphrase: ")
	if err != nil {
		return "", fmt.Errorf("could not read passphrase: %v", err)
	}

	p := string(pass)
	if p == "" {
		return "", fmt.Errorf("Passphrase can't be blank.")
	}
	return p, nil
}

func PassphrasePromptForEncryption() (string, error) {
	pass, err := readPassphrase("Enter passphrase (leave empty to autogenerate a secure one):")
	if err != nil {
		return "", fmt.Errorf("could not read passphrase: %v", err)
	}
	p := string(pass)
	if p == "" {
		var words []string
		for i := 0; i < 10; i++ {
			words = append(words, randomWord())
		}
		p = strings.Join(words, "-")
		// TODO: consider printing this to the terminal, instead of stderr.
		fmt.Fprintf(os.Stderr, "Using the autogenerated passphrase %q.\n", p)
	} else {
		confirm, err := readPassphrase("Confirm passphrase:")
		if err != nil {
			return "", fmt.Errorf("could not read passphrase: %v", err)
		}
		if string(confirm) != p {
			return "", fmt.Errorf("passphrases didn't match")
		}
	}
	return p, nil
}


// readPassphrase reads a passphrase from the terminal. It does not read from a
// non-terminal stdin, so it does not check stdinInUse.
func readPassphrase(prompt string) ([]byte, error) {
	var in, out *os.File
	if runtime.GOOS == "windows" {
		var err error
		in, err = os.OpenFile("CONIN$", os.O_RDWR, 0)
		if err != nil {
			return nil, err
		}
		defer in.Close()
		out, err = os.OpenFile("CONOUT$", os.O_WRONLY, 0)
		if err != nil {
			return nil, err
		}
		defer out.Close()
	} else if _, err := os.Stat("/dev/tty"); err == nil {
		tty, err := os.OpenFile("/dev/tty", os.O_RDWR, 0)
		if err != nil {
			return nil, err
		}
		defer tty.Close()
		in, out = tty, tty
	} else {
		if !term.IsTerminal(int(os.Stdin.Fd())) {
			return nil, fmt.Errorf("standard input is not a terminal, and /dev/tty is not available: %v", err)
		}
		in, out = os.Stdin, os.Stderr
	}
	fmt.Fprintf(out, "%s ", prompt)
	// Use CRLF to work around an apparent bug in WSL2's handling of CONOUT$.
	// Only when running a Windows binary from WSL2, the cursor would not go
	// back to the start of the line with a simple LF. Honestly, it's impressive
	// CONIN$ and CONOUT$ even work at all inside WSL2.
	defer fmt.Fprintf(out, "\r\n")
	return term.ReadPassword(int(in.Fd()))
}

func randomWord() string {
	buf := make([]byte, 2)
	if _, err := rand.Read(buf); err != nil {
		panic(err)
	}

	n := binary.BigEndian.Uint16(buf)
	return wordList[int(n)%2048]
}

// wordlist is the BIP39 list of 2048 english words, and it's used to generate
// the suggested passphrases.
var wordList = strings.Split(`abandon ability able about above absent 
absorb abstract absurd abuse access accident account accuse achieve acid 
acoustic acquire across act action actor actress actual adapt add addict 
address adjust admit adult advance advice aerobic affair afford afraid 
again age agent agree ahead aim air airport aisle alarm album alcohol 
alert alien all alley allow almost alone alpha already also alter always 
amateur amazing among amount amused analyst anchor ancient anger angle 
angry animal ankle announce annual another answer antenna antique anxiety
any apart apology appear apple approve april arch arctic area arena argue
arm armed armor army around arrange arrest arrive arrow art artefact 
artist artwork ask aspect assault asset assist assume asthma athlete atom
attack attend attitude attract auction audit august aunt author auto 
autumn average avocado avoid awake aware away awesome awful awkward axis 
baby bachelor bacon badge bag balance balcony ball bamboo banana banner 
bar barely bargain barrel base basic basket battle beach bean beauty 
because become beef before begin behave behind believe below belt bench 
benefit best betray better between beyond bicycle bid bike bind biology 
bird birth bitter black blade blame blanket blast bleak bless blind blood
blossom blouse blue blur blush board boat body boil bomb bone bonus book 
boost border boring borrow boss bottom bounce box boy bracket brain brand
brass brave bread breeze brick bridge brief bright bring brisk broccoli 
broken bronze broom brother brown brush bubble buddy budget buffalo build
bulb bulk bullet bundle bunker burden burger burst bus business busy 
butter buyer buzz cabbage cabin cable cactus cage cake call calm camera 
camp can canal cancel candy cannon canoe canvas canyon capable capital 
captain car carbon card cargo carpet carry cart case cash casino castle 
casual cat catalog catch category cattle caught cause caution cave 
ceiling celery cement census century cereal certain chair chalk champion 
change chaos chapter charge chase chat cheap check cheese chef cherry 
chest chicken chief child chimney choice choose chronic chuckle chunk 
churn cigar cinnamon circle citizen city civil claim clap clarify claw 
clay clean clerk clever click client cliff climb clinic clip clock clog 
close cloth cloud clown club clump cluster clutch coach coast coconut 
code coffee coil coin collect color column combine come comfort comic 
common company concert conduct confirm congress connect consider control 
convince cook cool copper copy coral core corn correct cost cotton couch 
country couple course cousin cover coyote crack cradle craft cram crane 
crash crater crawl crazy cream credit creek crew cricket crime crisp 
critic crop cross crouch crowd crucial cruel cruise crumble crunch crush 
cry crystal cube culture cup cupboard curious current curtain curve 
cushion custom cute cycle dad damage damp dance danger daring dash 
daughter dawn day deal debate debris decade december decide decline 
decorate decrease deer defense define defy degree delay deliver demand 
demise denial dentist deny depart depend deposit depth deputy derive 
describe desert design desk despair destroy detail detect develop device 
devote diagram dial diamond diary dice diesel diet differ digital dignity
dilemma dinner dinosaur direct dirt disagree discover disease dish 
dismiss disorder display distance divert divide divorce dizzy doctor 
document dog doll dolphin domain donate donkey donor door dose double 
dove draft dragon drama drastic draw dream dress drift drill drink drip 
drive drop drum dry duck dumb dune during dust dutch duty dwarf dynamic 
eager eagle early earn earth easily east easy echo ecology economy edge 
edit educate effort egg eight either elbow elder electric elegant element
elephant elevator elite else embark embody embrace emerge emotion employ 
empower empty enable enact end endless endorse enemy energy enforce 
engage engine enhance enjoy enlist enough enrich enroll ensure enter 
entire entry envelope episode equal equip era erase erode erosion error 
erupt escape essay essence estate eternal ethics evidence evil evoke 
evolve exact example excess exchange excite exclude excuse execute 
exercise exhaust exhibit exile exist exit exotic expand expect expire 
explain expose express extend extra eye eyebrow fabric face faculty fade 
faint faith fall false fame family famous fan fancy fantasy farm fashion 
fat fatal father fatigue fault favorite feature february federal fee feed
feel female fence festival fetch fever few fiber fiction field figure 
file film filter final find fine finger finish fire firm first fiscal 
fish fit fitness fix flag flame flash flat flavor flee flight flip float 
flock floor flower fluid flush fly foam focus fog foil fold follow food 
foot force forest forget fork fortune forum forward fossil foster found 
fox fragile frame frequent fresh friend fringe frog front frost frown 
frozen fruit fuel fun funny furnace fury future gadget gain galaxy 
gallery game gap garage garbage garden garlic garment gas gasp gate 
gather gauge gaze general genius genre gentle genuine gesture ghost giant
gift giggle ginger giraffe girl give glad glance glare glass glide 
glimpse globe gloom glory glove glow glue goat goddess gold good goose 
gorilla gospel gossip govern gown grab grace grain grant grape grass 
gravity great green grid grief grit grocery group grow grunt guard guess 
guide guilt guitar gun gym habit hair half hammer hamster hand happy 
harbor hard harsh harvest hat have hawk hazard head health heart heavy 
hedgehog height hello helmet help hen hero hidden high hill hint hip hire
history hobby hockey hold hole holiday hollow home honey hood hope horn 
horror horse hospital host hotel hour hover hub huge human humble humor 
hundred hungry hunt hurdle hurry hurt husband hybrid ice icon idea 
identify idle ignore ill illegal illness image imitate immense immune 
impact impose improve impulse inch include income increase index indicate
indoor industry infant inflict inform inhale inherit initial inject 
injury inmate inner innocent input inquiry insane insect inside inspire 
install intact interest into invest invite involve iron island isolate 
issue item ivory jacket jaguar jar jazz jealous jeans jelly jewel job 
join joke journey joy judge juice jump jungle junior junk just kangaroo 
keen keep ketchup key kick kid kidney kind kingdom kiss kit kitchen kite 
kitten kiwi knee knife knock know lab label labor ladder lady lake lamp 
language laptop large later latin laugh laundry lava law lawn lawsuit 
layer lazy leader leaf learn leave lecture left leg legal legend leisure 
lemon lend length lens leopard lesson letter level liar liberty library 
license life lift light like limb limit link lion liquid list little live
lizard load loan lobster local lock logic lonely long loop lottery loud 
lounge love loyal lucky luggage lumber lunar lunch luxury lyrics machine 
mad magic magnet maid mail main major make mammal man manage mandate 
mango mansion manual maple marble march margin marine market marriage 
mask mass master match material math matrix matter maximum maze meadow 
mean measure meat mechanic medal media melody melt member memory mention 
menu mercy merge merit merry mesh message metal method middle midnight 
milk million mimic mind minimum minor minute miracle mirror misery miss 
mistake mix mixed mixture mobile model modify mom moment monitor monkey 
monster month moon moral more morning mosquito mother motion motor 
mountain mouse move movie much muffin mule multiply muscle museum 
mushroom music must mutual myself mystery myth naive name napkin narrow 
nasty nation nature near neck need negative neglect neither nephew nerve 
nest net network neutral never news next nice night noble noise nominee 
noodle normal north nose notable note nothing notice novel now nuclear 
number nurse nut oak obey object oblige obscure observe obtain obvious 
occur ocean october odor off offer office often oil okay old olive 
olympic omit once one onion online only open opera opinion oppose option 
orange orbit orchard order ordinary organ orient original orphan ostrich 
other outdoor outer output outside oval oven over own owner oxygen oyster
ozone pact paddle page pair palace palm panda panel panic panther paper 
parade parent park parrot party pass patch path patient patrol pattern 
pause pave payment peace peanut pear peasant pelican pen penalty pencil 
people pepper perfect permit person pet phone photo phrase physical piano
picnic picture piece pig pigeon pill pilot pink pioneer pipe pistol pitch
pizza place planet plastic plate play please pledge pluck plug plunge 
poem poet point polar pole police pond pony pool popular portion position
possible post potato pottery poverty powder power practice praise predict
prefer prepare present pretty prevent price pride primary print priority 
prison private prize problem process produce profit program project 
promote proof property prosper protect proud provide public pudding pull 
pulp pulse pumpkin punch pupil puppy purchase purity purpose purse push 
put puzzle pyramid quality quantum quarter question quick quit quiz quote
rabbit raccoon race rack radar radio rail rain raise rally ramp ranch 
random range rapid rare rate rather raven raw razor ready real reason 
rebel rebuild recall receive recipe record recycle reduce reflect reform 
refuse region regret regular reject relax release relief rely remain 
remember remind remove render renew rent reopen repair repeat replace 
report require rescue resemble resist resource response result retire 
retreat return reunion reveal review reward rhythm rib ribbon rice rich 
ride ridge rifle right rigid ring riot ripple risk ritual rival river 
road roast robot robust rocket romance roof rookie room rose rotate rough
round route royal rubber rude rug rule run runway rural sad saddle 
sadness safe sail salad salmon salon salt salute same sample sand satisfy
satoshi sauce sausage save say scale scan scare scatter scene scheme 
school science scissors scorpion scout scrap screen script scrub sea 
search season seat second secret section security seed seek segment 
select sell seminar senior sense sentence series service session settle 
setup seven shadow shaft shallow share shed shell sheriff shield shift 
shine ship shiver shock shoe shoot shop short shoulder shove shrimp shrug
shuffle shy sibling sick side siege sight sign silent silk silly silver 
similar simple since sing siren sister situate six size skate sketch ski 
skill skin skirt skull slab slam sleep slender slice slide slight slim 
slogan slot slow slush small smart smile smoke smooth snack snake snap 
sniff snow soap soccer social sock soda soft solar soldier solid solution
solve someone song soon sorry sort soul sound soup source south space 
spare spatial spawn speak special speed spell spend sphere spice spider 
spike spin spirit split spoil sponsor spoon sport spot spray spread 
spring spy square squeeze squirrel stable stadium staff stage stairs 
stamp stand start state stay steak steel stem step stereo stick still 
sting stock stomach stone stool story stove strategy street strike strong
struggle student stuff stumble style subject submit subway success such 
sudden suffer sugar suggest suit summer sun sunny sunset super supply 
supreme sure surface surge surprise surround survey suspect sustain 
swallow swamp swap swarm swear sweet swift swim swing switch sword symbol
symptom syrup system table tackle tag tail talent talk tank tape target 
task taste tattoo taxi teach team tell ten tenant tennis tent term test 
text thank that theme then theory there they thing this thought three 
thrive throw thumb thunder ticket tide tiger tilt timber time tiny tip 
tired tissue title toast tobacco today toddler toe together toilet token 
tomato tomorrow tone tongue tonight tool tooth top topic topple torch 
tornado tortoise toss total tourist toward tower town toy track trade 
traffic tragic train transfer trap trash travel tray treat tree trend 
trial tribe trick trigger trim trip trophy trouble truck true truly 
trumpet trust truth try tube tuition tumble tuna tunnel turkey turn 
turtle twelve twenty twice twin twist two type typical ugly umbrella 
unable unaware uncle uncover under undo unfair unfold unhappy uniform 
unique unit universe unknown unlock until unusual unveil update upgrade 
uphold upon upper upset urban urge usage use used useful useless usual 
utility vacant vacuum vague valid valley valve van vanish vapor various 
vast vault vehicle velvet vendor venture venue verb verify version very 
vessel veteran viable vibrant vicious victory video view village vintage 
violin virtual virus visa visit visual vital vivid vocal voice void 
volcano volume vote voyage wage wagon wait walk wall walnut want warfare 
warm warrior wash wasp waste water wave way wealth weapon wear weasel 
weather web wedding weekend weird welcome west wet whale what wheat wheel
when where whip whisper wide width wife wild will win window wine wing 
wink winner winter wire wisdom wise wish witness wolf woman wonder wood 
wool word work world worry worth wrap wreck wrestle wrist write wrong 
yard year yellow you young youth zebra zero zone zoo`, " ")