System for protecting integrity of transaction data

A method of storing data in a blockchain, comprising:

• receiving, at a storage interface, data to be stored in the blockchain;
• computing validation data for validating integrity of the data;
• creating a storage record including the data and writing the storage record to the blockchain using a first interface of the blockchain;
• and
• creating a validation record including the validation data and writing the validation record to the blockchain using a second interface of the blockchain.

A method of validating a storage record, comprising:

• retrieving the storage record including stored data from a first storage domain;
• computing validation data from the stored data;
• retrieving a validation record from a second storage domain, the second storage domain comprising a blockchain, wherein the validation record comprises validation data previously computed for the storage record;
• comparing the computed validation data to the validation data in the retrieved validation record;
• and
• outputting a validation result in dependence on the comparison.