# \[v0.9.0\] First proof-of-concept release

**URL:** https://forum.duniter.org/t/v0-9-0-first-proof-of-concept-release/64
**Category:** Nodes
**Created:** [18 November 2014 12:45 UTC](https://forum.duniter.org/t/v0-9-0-first-proof-of-concept-release/64 "2014-11-18T12:45:57Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![cgeek](https://forum.duniter.org/user_avatar/forum.duniter.org/cgeek/32/279_2.png) [@cgeek](https://forum.duniter.org/u/cgeek)
#### Post date: [18 November 2014 12:45 UTC](https://forum.duniter.org/t/v0-9-0-first-proof-of-concept-release/64/1 "2014-11-18T12:45:57Z")

</div>

Here we are! The _first_ version of uCoin software gathering all the required core features.

GitHub link: [v0.9.0](https://github.com/ucoin-io/ucoin/releases)

You will find below a “log” of changes introduced with this version.

### Quick overview

This release is a proof-of-concept and gathers all required features to build a free currency. _However_, software still requires lots of tests, and lacks several useful tools to use it efficiently.

Use it for _testing_ and _demos_ purposes only!

### New features

- time reference and UD amount are now written in the blockchain
- transactions (both Dividend and Transfer) are now handled and written in the blockchain
- it is now possible to create a network of nodes
- it is now possible to synchronize the blockchain from an existing node to a new/unsynced node

### Changes

#### Certifications & Memberships

This kind of data is now _tied to a given blockchain_. It means that a certification or membership made for a given blockchain _cannot_ be used for another blockchain, even if the currency name is the same for the 2 blockchains.

This link is materialized by the writing of the number + fingerprint from an existing block in the blockchain into the Certification & Membership documents.

This change was made for 2 reasons:

1. We do not want signed documents to be reused in a context it was meant for.
2. We do not want the possibility to sign documents _dated in the future_.

Thus, blockchain time (tblock = block number + fingerprint) reference has the required property for our two goals: it targets without ambiguity the blockchain state at a given `t` time, and tblock has the property to be unpredictable.

#### Proof-of-work difficulty

Difficulty rules has changed, and I hope it is really both _easier_ to understand, and covers more use cases to counter potential spam attacks.