How to use the command 'sn' with Mono StrongName Utility (with examples)
The ‘sn’ command is a versatile utility within the Mono framework, used principally for managing the signing and verification of Intermediate Language (IL) assemblies. This tool provides functionalities similar to the StrongName utility in .NET, enabling developers to generate keys, sign assemblies, and manage strong names, which are essential for ensuring assembly integrity and authenticity in a .NET environment. The following examples illustrate some of the primary uses of the ‘sn’ command utility, showing how to generate keys, re-sign assemblies, and manage public keys.
Use case 1: Generate a new StrongNaming key
Code:
sn -k path/to/key.snk
Motivation:
When starting a new project or when you require a new strong name key pair for signing assemblies, you need to generate a new key. This key is crucial for signing assemblies, thereby ensuring the authenticity and version control of your software components. This process guarantees that only assemblies signed with the specific private key can be executed, enforcing security and maintaining trust.
Explanation:
sn: This is the Mono StrongName utility command.-k: This option specifies the creation of a key pair.path/to/key.snk: This is the designated path where the new StrongName key pair (.snk file) will be saved. It’s important to store this securely as it contains the private key used for signing.
Example Output:
If successful, the command quietly completes with no console output, but the new key file (key.snk) will appear at your specified path.
Use case 2: Re-sign an assembly with the specified private key
Code:
sn -R path/to/assembly.dll path/to/key_pair.snk
Motivation:
Over time, you might need to modify or update an assembly, which will then need to be re-signed using the strong name key. This step is fundamental when a private key has been updated, or an assembly needs to be resigned due to changes in the software lifecycle, ensuring the assembly remains tamper-proof and authenticated by the signer.
Explanation:
sn: Calls the Mono StrongName utility.-R: This switch tells the command to re-sign the specified IL assembly.path/to/assembly.dll: Specifies the path to the assembly file that needs re-signing. An assembly file is a compiled code library ready for deployment.path/to/key_pair.snk: Indicates the path to the strong name key pair to be used for re-signing the assembly.
Example Output:
Typically, this action doesn’t produce console output if it succeeds. The specified assembly is re-signed with the provided key pair, ensuring strong name integrity is maintained.
Use case 3: Show the public key of the private key that was used to sign an assembly
Code:
sn -T path/to/assembly.exe
Motivation:
Knowing the public key associated with an assembly is crucial for security audits and maintaining a secure deployment pipeline. It allows developers and security professionals to verify that an assembly has been signed with the expected key, helping to prevent vulnerabilities due to misidentification of executables.
Explanation:
sn: Utilizes the Mono StrongName utility.-T: This command switch requests the display of the public key for the specified file.path/to/assembly.exe: The location of the assembly file whose public key you wish to reveal. This can be used to confirm which key was used for signing.
Example Output:
The console will output the public key in a hexadecimal format, something akin to:
Public key is
0024000004800000940000000602000000240000525341310004000001000100d7...
This output helps in verifying signature authenticity.
Use case 4: Extract the public key to a file
Code:
sn -e path/to/assembly.dll path/to/output.pub
Motivation:
In scenarios requiring distribution of an assembly’s public key for verification purposes without exposing the private key, extracting and sharing only the public key is critical. This extraction helps organizations maintain control over key management while facilitating public verification processes.
Explanation:
sn: Refers to the Mono StrongName utility.-e: This command specifies the extraction of the public key from an assembly.path/to/assembly.dll: Path to the assembly from which the public key will be extracted.path/to/output.pub: Target location and file where the public key will be saved. It allows for easy distribution and verification without compromising the private key.
Example Output:
Again, this operation produces no console output if successful. A new .pub file containing the public key is created at the location specified, ready for distribution or verification use.
Conclusion
Using the ‘sn’ command effectively within the Mono environment allows for consistent and secure assembly signing practices, critical for trusted application deployment. Whether generating new keys, re-signing assemblies, or managing public keys, the utility helps maintain the integrity and security needed for robust software development in modern .NET ecosystems.
