Immutable Data Integrity with Oracle's Blockchain Tables

 Blockchain tables in Oracle Database implement a unique data organization model, forming chains of insert-only rows. Each row, excluding the first, links back to the previous row using cryptographic hashing. This hashing method leverages row data and the hash of the preceding row to identify any unauthorized modifications through specialized verification procedures. The added capability to store user signatures significantly enhances security against tampering and unauthorized alterations.

Beyond thwarting unauthorized changes initiated by rogue or compromised insiders, blockchain tables boast powerful functionality:

• Identification of illicit modifications made by circumventing Oracle Database protocols.
• Detection of user impersonation and unauthorized data insertions on behalf of another user.
• Safeguarding against data tampering, certifying that all data inserted into the table was done legitimately.
• The chaining mechanism ensures that each row remains linked to its predecessor through cryptographic hashing. Altering any row disrupts this chain, immediately signaling tampering. However, this additional layer of security necessitates increased processing time during commit operations to chain rows effectively.

Let's explore how to create and interact with a blockchain table in Oracle Database through the following example:

-- Creating a blockchain table

SQL> CREATE BLOCKCHAIN TABLE secure_data_table (data_value VARCHAR2(128), sequence_number NUMBER)

     NO DROP UNTIL 1 DAYS IDLE

     NO DELETE UNTIL 16 DAYS AFTER INSERT

     HASHING USING "SHA2_512" VERSION "v1";    

Table created.

-- Inserting data into the blockchain table

SQL> INSERT INTO secure_data_table VALUES ('Value1', 1);

1 row created.

SQL> COMMIT;

Commit complete.

-- Querying metadata of the blockchain table

SQL> SELECT column_id, column_name, nullable, hidden_column

     FROM all_tab_cols

     WHERE table_name LIKE 'SECURE_DATA_%'

     ORDER BY column_id;

-- Viewing blockchain table details

SQL> SELECT * FROM dba_blockchain_tables;

In this example, secure_data_table is our blockchain table, ensuring immutable data integrity and providing robust security against unauthorized changes. The SHA2_512 hashing algorithm is employed to maintain the integrity of each chained row, guaranteeing data authenticity and traceability within Oracle Database's secure environment.