Idena security model update

Published in
3 min readFeb 24, 2020


We plan significant changes in the Idena network security model. The main purpose of the improvements is preventing bots from collecting invitations and solving flips randomly. These changes will be released during the next several hard forks.

  1. Short session extension
  • The short session will be extended from 5 to 6 flips (the short session time frame does not change)
  • The threshold for the short session validation will be increased to 60% (4 out of 6 flips, 3 out of 5, 2.5 out of 4, 2 out of 3, 1 out of 1)
  • In order to become Verified, more than 12 flips have to be solved in total

Motivation: Decreasing probability of successful flips solving with random guessing. Additionally, it will make validating two identities by one person harder.

2. Human status with the stake protection for aged identities

  • The Human status will be introduced: It will require at least 24 flips solved at short sessions with minimum total score of 92% (at least 4 short sessions solved in total)
  • A Human gets a right to fail the short session without being killed (the identity becomes Suspended), also a Human is eligible for extra flip and invitation rewards (see proposals #5–6)

Motivation: Introducing additional safety guarantees for the protocol, incentivizing aged identities to keep the accumulated stake. Currently participants tend to terminate their identities and withdraw the stake due to a risk of the short session failure.

Validation results as of February 23, 2020 (epochs: #0007 — #0037)

The probability of getting the Human status is growing with the age of identity.

Verified / Human status distribution depending on the total number of flips solved (short sessions)

3. Lottery-based rewards for non-spent invitations to prevent sporadic invitations

  • A person who does not share their invitation will be rewarded with at least 1/3 of the basic invitation reward with 50% probability to win 2/3 of the basic invitation reward for a non-spent invitation.

Motivation: Preventing waste of invitations by participants. Participants tend to give away their non-spent invitations randomly in the last minutes before the validation in order to get a chance of earning a reward. These last minute invitations are mostly collected by bots.

4. Discrimination of identities with the Newbie status

  • 80% of all earned coins will be frozen in the stake wallet until a Newbie becomes Verified
  • 20% of earned coins will be mined to the main wallet
  • 60% of staked coins will be sent back to the main wallet once a Newbie becomes Verified
  • A Newbie will not be able to terminate their identities to withdraw the stake.

Motivation: Decreasing rewards for bots which have no intention to get the Verified status. Honest participants will not be penalized since they get their frozen coins back once they reach the Verified status.

5. Additional flips submission

  • A Verified identity will be allowed to submit 1 extra flip
  • A Human identity will be allowed to submit 2 extra flips
  • Extra flips creation will be rewarded

Motivation: Increasing the total number of flip submissions in the network in order to cover the short session extension from 5 to 6 flips.

6. More invitations for Humans and less for Verified

  • A Human will be allowed to issue extra invitations
  • A Verified identity may lose their right to issue invitations if the Total score drops below a certain threshold

Motivation: Preventing bots that randomly reached 75% accuracy from issuing invitations while keeping the total number of invitations in the network at the current level.

The hard fork is planned for February 28, 2020. We plan to release proposals #1–5. Proposal #6 will be released with the subsequent fork when sufficient statistics for the Human status is collected. We will keep you updated.




Proof-of-Person blockchain. Idena is a novel way to formalize people on the web: