Calculate hash values

This article explains how to hash text and file data and calculate the hash value.

Decrypt files and textPower Automate Desktop also provides several actions related to security and encryption. This article explains how to decrypt encrypted text data.

Encrypt files and textPower Automate Desktop is designed to work not only with on-premises software but also with cloud services, and it provides several actions related to security and encryption. This article explains how to encrypt a text file.

About hashing

Hashing is a technique that passes the original data through a hash function to generate a fixed-length string (a hash value).

Hashing the same data always produces the same hash value, and in practice, different data never produces the same hash value.

Because you can check whether two pieces of data are identical just by comparing their hash values, without comparing the data itself, hashing is used for purposes such as verifying that data hasn’t been tampered with.

Also, in practice, you can’t work out the original data from a hash value.

The action to use

The action used here is called “Hash text.”

Details of the “Hash text” action

The action has the following parameters.

Parameter	Value
Hash algorithm	The algorithm to use for hashing (SHA256 / SHA384 / SHA512)
Encoding	The encoding (character encoding) of the text to hash
Text to hash	The text to hash

The hashing result is stored in the variable HashedText. The same text produces a different hash value if the encoding is different, so use the same encoding when you compare hash values (the default is “Unicode”).

Tip

To hash the contents of a file, use the “Hash from file” action. There are also “Hash text with key” and “Hash from file with key” actions, which calculate keyed hashes (HMAC SHA256 / HMAC SHA384 / HMAC SHA512).

Implement the action

Add the sample flow by copying and pasting

As a sample, I prepared a flow that calculates a hash value from the specified text data.

Copy the following code and paste it into the Power Automate Desktop flow designer to add the actions.

SET HugeData TO $'''%'Data too large to transfer easily'%'''
Cryptography.HashText HashAlgorithm: Cryptography.HashAlgorithm.SHA256 Encoding: Cryptography.EncryptionEncoding.UTF8 TextToHash: HugeData HashedText=> HashedText

Implement in Power Automate Desktop

1. In “Search actions,” type “Hash text.”

2. Set the parameters as follows. %HugeData% is the variable created on the first line of the sample flow (the “Set variable” action).

   Parameter	Value
   Hash algorithm	SHA256
   Encoding	UTF-8
   Text to hash	%HugeData%

3. When you run the flow, the result of hashing the specified text data is stored in a variable.

Possible exceptions

An error may occur when hashing runs.

We recommend adding error handling with an “On block error” block.