Trusto Hybrid Biometric Smart Contracts runtime
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Trusto Hybrid Biometric Smart Contracts (HBS) Library

The HBS library provides key services for Trusto network:

  • biometric key signing services
  • transaction validation
  • smart contracts storage and execution

It uses both Trusto Hybrid Biometric Blockchain protocol and Trusto Biometric Document Blockchain protocol libraries to store, validate and execute transactions.

It implements the execution engine and the run time services of the trusto's smart contracts description language which is a touring complete, declarative, functional language featuring immutable state and formal verification of the contract rules correcteness.


The only supported installation method, right now, is from source files, stack.

Building from source


You will need to download and install stack.

You also need git to get the latest source code.

Download and install Trusto Hybrid Biometric Blockchain protocol library and Trusto Document Biometric Blockchain protocol libraries.

Get the source

git clone


To build the project, you need first to run stack setup. This command will make sure you have the correct haskell compiler, and, if you don't have it, it will download and install one in a separate location in such a way to not interract with your existing haskell environment (if you have one):

#> cd /the/location/of/trusto/hbs
#> stack setup

After the setup (you only need to run setup once) you may build, test or install the software. To build, simply issue:

#> stack build

To run the tests:

#> stack test

To install it in the stack's install directory, type:

#> stack install


The biometric blockchain smart contracts library provides:

  • biometric key signing services
  • smart contracts runtime supporting the execution of smart contracts
  • smart contracts execution engine
  • transactions validation engine for hybrid biometric blockchain

The biometric key

The library provides access to biometric key signing services. It does not implement the biometric key, but rather access them from an external service provider, perhaps a hardware device.

The smart contracts runtime

The runtime provides the implementation of services available for contracts, like accessing the transaction and document blockchains.

The smart contracts execution engine

It executes the smart contract code. It uses the smart contracts runtime to provide access to different services.

The transaction validation service

The Trusto Hybrid Biometric Blockchain validates trasactions using smart contracts code. The code is stored in the document blockchain, and the transaction validation service uses the document hash in the document blockchain to locate and run the validation code.