HYDRA Public Ledger & Token

The Hydraledger Token provides a decentralized source of trust for the IOP Stack, rewarding users who maintain the network while keeping cost and fees low.

What we actually store on the Hydra ledger?

We only store facts that require ordering or timestamping in a decentralized manner such as changes in authentication and authorization, or hashes of signed documents. These facts do not contain any sensitive or personal data, hence storing them is more than GDPR compliant.

For example when we want to validate a legal document that was signed by a CEO with a key, we also want to know whether that key was in use by the person signing the document at the moment, and whether they had the CEO role at the moment of signing. That is why you can register and revoke rights of keys to an identity and timestamping document hashes on the ledger.

How you can manage DID documents?

You can create an infinite amount of DIDs for FREE in your wallet. You only need to interact with the Hydra ledger if you would like to change its authentication or authorization methods.

Doing that you will have a decentralized IAM solution, which we call IOP SSI (Self-Sovereign Identity framework).

Hydra Transactions Typical Bytes Typical Fee
transfer 100 0.003Ħ
vote 100 0.003Ħ
unvote 100 0.003Ħ
register delegate 400000 12.0Ħ
resign delegate 400000 12.0Ħ
extra: vendor field 255 0.00765Ħ
SSI operations Typical Bytes Typical Fee
(many of these can all be put into a single atomic transaction)
proof of existence 40 0.0012Ħ
"create DID" 0
add key 360 0.0108Ħ
remove key 360 0.0108Ħ
add right 360 0.0108Ħ
remove right 360 0.0108Ħ
tombstone DID 360 0.0108Ħ
DNS operations Typical Bytes Typical Fee
(many of these can all be put into a single atomic transaction)
register 400 0.012Ħ
update 400 0.012Ħ
transfer 400 0.012Ħ
renew 400 0.012Ħ
delete 400 0.012Ħ
Credential operations Typical Bytes Typical Fee
(completely off-chain, federated network of authority and inspection services)
witness request N/A N/A
inspect presentation N/A N/A

What is on the Hydra public ledger?

You might think that we market ourselves that we store everything decentralized on the ledger, but the opposite is true. In most cases it’s enough to store minimal data on chain that’s publicly available for anyone to achieve the same goal. Hence, we don’t store any private and/or sensitive data publicly available. To read more about the architecture of the Hydra network, please visit our Developer Portal:

No Gatekeepers

Instead of relying on a trusted committee of gatekeepers (for instance designated certificate authorities), the Hydra blockchain relies on a decentralized consensus mechanism to protect and maintain your identity.
Instead of trusting a corporation, users only need to trust the code. The Hydra Token incentivizes everyone to act honestly when maintaining the chain.


Hydra currently uses a consensus mechanism called delegated Proof-of-Stake (DPoS). Hydra token holders use their staked tokens to elect 53 delegates who forge new blocks and create new tokens.

These delegates share a large percentage of the block rewards with their voters. Delegates also earn voter share by contributing to the project or by helping new users. Delegates need to be online and run a reliable node to forge new blocks.