VBA & Macro Problems

How to Compare Excel VBA File Hashes with an Access Database

Ayan Masood Oct 15, 2026 871 views

Question details

The user needs a method to verify if an Excel VBA tool matches the latest version stored in a shared Microsoft Access database.

How to Compare Excel VBA File Hashes with an Access Database

Product: Microsoft Excel, Microsoft Access
Device & OS: not provided
Scenario: Implementing version control and file-integrity checks for an Excel VBA workbook distributed alongside a central Access database.
Observed behavior: Requires a reliable method to calculate the workbook's hash and compare it to the database record, utilizing Windows API functions or an alternative approach.

Before you start

Before working with Windows API functions in VBA, ensure your workbook is saved as a Macro-Enabled format (.xlsm) and back up your original Excel file and Access database.

Solution 1Recommended

Use Windows API Functions to Compare Cryptographic File Hashes

Calculate a cryptographic hash of the Excel file using Windows API functions and compare it to the hash stored in your Access database.

This method provides the strongest file-integrity verification. You will need to use several Windows API functions in sequence to initialize the cryptographic context, create the hash object, process the file data, and extract the resulting hash value.

Declare Windows API Functions

Open the VBA Editor (ALT + F11) and declare the necessary Windows API functions at the top of a standard module: CryptAcquireContext, CryptCreateHash, CryptHashData, and CryptGetHashParam.

Calculate the Current File Hash

Write a VBA function that reads the Excel file as a byte array, passes the data through CryptHashData, and retrieves the final hexadecimal hash string using CryptGetHashParam.

Compare Against the Access Database

Use an ADO or DAO connection in your VBA code to query your Microsoft Access database. Retrieve the stored hash for the latest released version and compare it with your dynamically calculated workbook hash.

Use Windows API Functions to Compare Cryptographic File Hashes

API Function Synergy: The mentioned Cryptographic API functions do not produce hashes independently. They must be used together in a specific order to successfully create and read a cryptographic hash.

Solution 2

Compare Last-Modified Dates for a Simpler Version Check

If strict cryptographic security is not required, comparing the file's last-modified date is a much simpler alternative to check versions.

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Frequently Asked Questions

Do I need to use all the Windows Cryptographic API functions together?

Yes. Functions like CryptAcquireContext, CryptCreateHash, CryptHashData, and CryptGetHashParam must be used in sequence. You initialize the provider context, create a hash object, feed file data into it, and finally retrieve the hash value.

Why use file hashes instead of version numbers or dates?

While version numbers or last-modified dates are simpler to implement, file hashes provide stronger file-integrity verification. A hash ensures that the file's exact contents have not been altered, modified, or corrupted.

Can I check the last-modified date instead of calculating a hash?

Yes, if you only need a basic version check, you can use the built-in VBA FileDateTime function to compare the workbook's last saved timestamp with a release date recorded in your Access database.

Excel & Data Problems