Mastering Linux Command Piping with OpenSSL: Encrypting String Inputs Made Easy

Описание: Learn how to efficiently encrypt string inputs in Linux using OpenSSL with command piping. Follow our guide to achieve consistent results.
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This video is based on the question https://stackoverflow.com/q/72993381/ asked by the user 'Om Sao' ( https://stackoverflow.com/u/2702249/ ) and on the answer https://stackoverflow.com/a/72997234/ provided by the user 'Om Sao' ( https://stackoverflow.com/u/2702249/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Mastering Linux Command Piping with OpenSSL: Encrypting String Inputs Made Easy

When working on a shell script that involves encryption, you may find yourself needing to use different sources of input. A common scenario is encrypting the contents of a file versus encrypting a string directly. While you might think the approach would be similar, subtle differences in how commands are piped can lead to unexpected results. In this post, we’ll explore a common issue with using OpenSSL to encrypt strings and how to correct it.

The Problem: Inconsistent Encryption Results

Imagine you have a file located at path and want to encrypt its content. The command that successfully works looks like this:

[[See Video to Reveal this Text or Code Snippet]]

This command correctly computes the SHA-256 hash of the file and encodes it in base64. However, when trying to encrypt a string stored in the variable $body using the following command:

[[See Video to Reveal this Text or Code Snippet]]

You notice that the output is entirely different. Why is this happening?

The Solution: Correct and Consistent Encryption

To resolve this issue, you need to ensure that your commands behave similarly for both file content and string input. Here’s how to do it correctly:

Step-by-Step Correction

Use the -binary Option: When working with string input, it's essential to include the -binary option in your OpenSSL command. This option ensures that the output is generated in binary format, aligning it with how the file input is processed.

Piping Input Properly: Instead of simply redirecting the output from openssl dgst -sha256, use the echo command to pipe the string into the openssl command directly.

Correct Command

Here’s the updated command that should now work correctly for the string $body:

[[See Video to Reveal this Text or Code Snippet]]

Important Points to Remember

Binary Mode is Crucial: The -binary option is what differentiates the outcome when comparing file contents and string inputs. Always use -binary when hashing to ensure consistency.

Consistent Command Structure: They should mirror the structure of your file input command. By maintaining a consistent approach, you reduce the likelihood of unexpected results.

By following these steps, you can successfully encrypt string inputs just as reliably as file contents, ensuring your data remains secure.



In summary, mastering the nuances of command piping in Linux can significantly enhance your scripting abilities, especially with OpenSSL in play. Enjoy encrypting your data with newfound confidence!