How to Use the Command 'minisign' (with Examples)

Minisign is a straightforward tool designed to sign files and verify their signatures. This utility provides an added security layer by allowing users to ensure the integrity and origin of their files. By generating cryptographic signatures, users can authenticate the information and reassure that the contents have not been tampered with by malicious actors. Below, we will explore various use cases of the ‘minisign’ command, including generating keys, signing files, adding comments to signatures, and verifying signatures.

Use case 1: Generate a New Keypair at the Default Location

Code:

minisign -G

Motivation:
Generating a new keypair is an essential first step for anyone looking to sign files with Minisign. The keypair consists of a private key used for signing and a public key for verification purposes. Having a unique keypair ensures that signatures can be uniquely attributed to you, maintaining trust in the signed files.

Explanation:

• -G: This flag tells Minisign to generate a new keypair. The keys are created at a default location on your system. The private key is stored securely, while the public key can be shared for others to verify your signatures.

Example Output:

Generating keypair...
Packed private key: ~/.minisign/minisign.key
Public key: ~/.minisign/minisign.pub
Please write down your passphrase. You will need it to use your private key.
Key pair generated.

Use case 2: Sign a File

Code:

minisign -Sm path/to/file

Motivation:
Signing a file is crucial for ensuring its authenticity and integrity. When you sign a file, you create a signature that others can use to verify that the file has not been altered since you created the signature.

Explanation:

• -S: This flag initiates the signing process.
• -m: This flag specifies the path to the file that you wish to sign. Replace path/to/file with the actual file path you are signing.

Example Output:

Signing... 
Signature: path/to/file.minisig

Use case 3: Sign a File with Comments

Code:

minisign -Sm path/to/file -c "Untrusted comment" -t "Trusted comment"

Motivation:
Comments enhance the signing process by adding context to the signatures. Trusted comments are part of the signature, thus they cannot be altered without invalidating the signature, while untrusted comments can be modified or added afterward. This feature provides more information about the file or the signing event itself.

Explanation:

• -S: Initiates the signing process.
• -m: Indicates the file path to be signed.
• -c: Adds an untrusted comment; any text stamped with this flag can be altered without affecting the signature’s validity.
• -t: Adds a trusted comment to the signature, ensuring the comment’s integrity since it is sealed with the signature.

Example Output:

Signing... 
Untrusted comment: Untrusted comment
Trusted comment: Trusted comment
Signature: path/to/file.minisig

Use case 4: Verify a File Using a Public Key File

Code:

minisign -Vm path/to/file -p path/to/publickey.pub

Motivation:
The ability to verify a file is the cornerstone of trust established through signing. Verifying a file with a specified public key ensures the file has not been altered since it was signed and confirms the signature was made by someone in possession of the corresponding private key.

Explanation:

• -V: Indicates the process of verification.
• -m: Specifies the file path of the document to be verified.
• -p: Indicates the path to the public key file necessary for verification.

Example Output:

Verification OK

Use case 5: Verify a File with Public Key as Base64 Literal

Code:

minisign -Vm path/to/file -P "public_key_base64"

Motivation:
Using a Base64 encoded public key offers a flexible means to verify signatures without needing a stored public key file. This is particularly useful when public keys are shared or stored in an encoded form in different mediums, such as emails or external databases.

Explanation:

• -V: Initiates verification.
• -m: Specifies the file to be verified.
• -P: Uses a Base64 encoded public key provided directly within the command instead of referring to a file.

Example Output:

Verification OK

Conclusion:

These examples illustrate the core functionalities of the ‘minisign’ command, showcasing how you can secure your files with digital signatures. Generating key pairs, signing files, adding comments, and verifying signatures are fundamental actions you may take to maintain the integrity and authenticity of your files effectively. Overall, Minisign provides a simple and efficient way to handle file verification and integrity on various platforms.