certutil Command Examples (with examples)

The certutil command is a versatile tool for managing and configuring certificate information in Windows. It can be used to perform various tasks such as dumping configuration information, encoding and decoding files, and generating cryptographic hashes. In this article, we will explore different use cases of the certutil command and provide code examples for each one.

1: Dumping Configuration Information or Files

certutil filename

Motivation: Dumping configuration information can be useful for troubleshooting or analyzing certificate-related issues. It allows you to view detailed information about certificate files, including certificate paths, issuers, and subject names.

Explanation: This command takes a file name as an argument and outputs the configuration information of the specified file.

Example Output:

CA Issuers - Contains the URL of the issuing Certification Authority (CA) for this certificate.

SVR Issuer - Contains the URL of the issuing Certification Authority (CA) for this certificate.

Public Key - Contains key value used to sign certificate.

Public Key Algorithm - Contains algorithm identifier (algorithm ID) for public key algorithm.

Signature Algorithm - Contains algorithm identifier (algorithm ID) for signature algorithm.

2: Encoding a File in Hexadecimal

certutil -encodehex path\to\input_file path\to\output_file

Motivation: Encoding a file in hexadecimal can be useful when you need to represent binary data in a human-readable format. It allows you to view the contents of a file as a series of hexadecimal values.

Explanation: This command takes the path to an input file and the path to an output file as arguments. It encodes the input file in hexadecimal format and saves the result to the output file.

Example Output (output_file):

48 65 6C 6C 6F 20 57 6F 72 6C 64 21

3: Encoding a File to Base64

certutil -encode path\to\input_file path\to\output_file

Motivation: Encoding a file to Base64 can be useful when you need to transmit or store binary data in a text format. It allows you to convert binary data into a string of ASCII characters, which can be easily handled by different systems.

Explanation: This command takes the path to an input file and the path to an output file as arguments. It encodes the input file to Base64 format and saves the result to the output file.

Example Output (output_file):

SGVsbG8gV29ybGQh

4: Decoding a Base64-encoded File

certutil -decode path\to\input_file path\to\output_file

Motivation: Decoding a Base64-encoded file is necessary when you want to retrieve the original binary data from a Base64 representation. It allows you to convert the encoded data back to its original format.

Explanation: This command takes the path to a Base64-encoded input file and the path to an output file as arguments. It decodes the input file and saves the decoded binary data to the output file.

Example Output (output_file):

Hello World!

5: Generating and Displaying a Cryptographic Hash

certutil -hashfile path\to\input_file md2|md4|md5|sha1|sha256|sha384|sha512

Motivation: Generating a cryptographic hash over a file is useful for verifying the integrity and authenticity of the file. It allows you to create a unique hash value that represents the contents of the file, making it easier to detect any changes or tampering.

Explanation: This command takes the path to an input file and a hash algorithm (md2, md4, md5, sha1, sha256, sha384, or sha512) as arguments. It generates a cryptographic hash over the input file using the specified algorithm and displays the hash value.

Example Output:

SHA1 hash of file path\to\input_file:
A45F20D48572C4FEDF30B81060D4C68C9FD5A4E9

By understanding these different use cases of the certutil command, you can effectively manage and configure certificate information in Windows systems. Whether you need to dump configuration information, encode or decode files, or generate cryptographic hashes, certutil provides you with the necessary tools to handle these tasks efficiently and securely.