In the world of digital transactions, maintaining the integrity and immutability of transaction data is paramount. Blnk leverages SHA-256 hashing to ensure that every transaction is securely recorded, verifiable, and immutable. Data hashing is a cryptographic process that converts input data of any size into a fixed-size string of characters, which is typically a digest representing the data. Blnk uses the SHA-256 hashing algorithm for this purpose, ensuring that each transaction is accompanied by a unique hash value that serves as its digital fingerprint.

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How Blnk implements SHA-256 hashing

When a transaction is processed in Blnk, the system generates a SHA-256 hash of the transaction’s details, including the amount, source, destination, reference, and any other relevant information. This hash is then stored alongside the transaction record. The SHA-256 algorithm ensures that even the slightest change in the transaction details would result in a completely different hash, thereby safeguarding against unauthorized modifications.

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Verifying transaction integrity

Users can verify the integrity of a transaction by recomputing the SHA-256 hash of the transaction details and comparing it with the hash stored in the Blnk. If the computed hash matches the stored hash, the transaction is confirmed to be intact and unaltered.

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Verifying a transaction hash

Consider a transaction with the following details:
Request
{
    "amount": 750000,
    "reference": "ref123",
    "currency": "USD",
    "source": "bln_source123",
    "destination": "bln_dest123"
}
To verify this transaction, concatenate the above details into a single string (excluding the hash) and compute the SHA-256 hash of this string. Using a SHA-256 hash function in your preferred programming language or a tool, you can generate the hash. For example, in Python: 
import hashlib

# Concatenate your transaction details
transaction_details = '750000ref123USDbln_source123bln_dest123'

# Compute the SHA-256 hash
hash_value = hashlib.sha256(transaction_details.encode()).hexdigest()

print(hash_value)
Compare this hash_value with the hash provided by Blnk for the transaction. If they match, the transaction’s integrity is verified.

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Benefits of hashing transactions

  1. Immutability: Once a transaction is recorded with its hash, it cannot be altered without changing the hash. This makes every transaction in Blnk immutable and secure against tampering.
  2. Verification: Users can independently verify the integrity of their transactions without relying on Blnk’s internal systems, enhancing trust and transparency.
  3. Security: SHA-256 is a cryptographic hash function, which means it is designed to be secure against collision attacks (where two different inputs produce the same output hash) and preimage attacks (finding an input based on its output hash).
  4. Efficiency: Hashing is a fast computational process, allowing for quick verification of transaction integrity without the need to compare all transaction details line by line.

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Protecting Transaction Integrity in Blnk

While SHA-256 ensures that transaction data remains verifiable, additional measures can help protect stored hashes from unauthorized modifications. Since Blnk records transaction hashes in its system, it is important to safeguard them against potential tampering. To enhance transaction integrity, we recommend implementing the following safeguards:
  1. External hash logging: Periodically logging transaction hashes to an immutable external storage system can provide an independent verification layer. This ensures that even if transaction data is modified internally, an external record remains intact for comparison.
  2. Audit trails: Enabling detailed logging of database changes helps detect and trace any unauthorized modifications to transaction records.
  3. Access controls: Restricting database and system access ensures that only authorized users or services can modify transaction data. Implementing role-based access control (RBAC) can further limit who can alter sensitive records.
  4. Automated integrity checks: Running scheduled integrity checks by recomputing hashes and comparing them against logged values helps identify inconsistencies and unauthorized changes.

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Need help?

We are very happy to help you make the most of Blnk, regardless of whether it is your first time or you are switching from another tool. To ask questions or discuss issues, please contact us or join our Discord community.