Package: secretshare
SecretShareA simple library implementing Adi Shamir's "How to share a secret" algorithm. It is currently very limited since it uses integer arithmetic with primes, thus limiting the size of the shared secret to 8192 bits (1024 bytes). A future version might implement some form of unlimited stream share, but it is not its current goal, which is being used on cryptographic applications.This library is part of theDungeon Password Managerproject.RequirementsPython 3.6+PassphraseInstallationClone the repo an runmake package-installor, for development purposes,make devenvironment. Install dependencies withpipenv installorpip install -r requirements.txt.UsagefromsecretshareimportSecret,SecretShare,Sharedefemail(recipient,body):"""Simulate sending an email."""print(f'Recipient:{recipient}- Body:{body}')# Generate a new random secretsecret=Secret()# Or use an existing onesecret.value=12345267890# Or directly: secret = Secret(1234567890)# If your secret is not an integer, you can use these methods# from_bytes()# from_base64()# from_hex()# Share the secretshare_count=5# How many pieces will the secret be split into?threshold=3# How many pieces are required to recover the secret?shamir=SecretShare(threshold,share_count,secret=secret)shares=shamir.split()print(shamir.shares)# [Share(point=1, value=110014556089737955654312725615756332615), Share(point=2, value=270561733948920165984210681299343881767), Share(point=3, value=141359166656608167526319259631339703839), Share(point=4, value=62689221133740423744013068043512010338), Share(point=5, value=34551897380316934637292106535860801264)]# shamir.shares are the same as `shares`, returned by the split() method# Now deliver the shares to each recipientrecipients=('r1@email.com','r2@email.com','r3@email.com','r4@email.com','r5@email.com')fori,shareinenumerate(shares):email(recipients[i],str(share))# Send in base64# A Share can be converted to several convenient formats:# bytes(share), share.to_bytes()# str(share)# share.to_hex(), hexlify(bytes(share))# share.to_base64()# Note: a Secret can be converted the very same way# To recover the secret, get the share from each holder# Each Share has a point and a values1=Share(1,335597737083070970356431407479895583486)s2=Share(2,138424231339574140617068979728677909704)s4=Share()# They are both encoded together for conveniences4.from_base64('BQBGQMaGiRzWb0gO3gGEotVL')# The share count and threshold information is NOT saved anywhere# so the developer must save it somewhere as it is public# information and there's no risk in storing it.# As a matter of fact, those parameters are not really needed to recover a# secret. If you provide less shares than the threshold then you will get a# secret value that will be incorrect. There's no way to tell from the result# whether the amount of shares are actually correct or not.shamir=SecretShare(threshold,share_count,shares=[s1,s2,s4])secret=shamir.combine()print(secret)# At/V1rI=print(int(secret))# 1234567890# If the wrong number of shares is provided, an incorrect result# is obtained. This is because this algorithm can't validate the result.# The developer should verify the secret obtained by comparing into# a hash, preferably using a secure KDF such as Argon2.# Alternatively, it might be more convenient to verify each share# against a hash: if the provided shares are valid the result# will be correct.DevelopingInstall the development requirements, run tests withmake testand lint withmake lint. Check for tests coverage withmake coverage(must be 100%).LicenseSecretShareis made byHacKanunder GNU GPL v3.0+. You are free to use, share, modify and share modifications under the terms of thatlicense.Copyright (C) 2018 HacKan (https://hackan.net)

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but WITHOUT ANY WARRANTY; without even the implied warranty of
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