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Strong Name Tool (Sn.exe)

The Strong Name tool helps sign assemblies with strong names. Sn.exe provides options for key management, signature generation, and signature verification.

sn [-quiet][option [parameter(s)]]
Option Description
-c [csp] Sets the default Cryptographic Service Provider (CSP) to use for strong name signing. This setting applies to the entire computer. If you do not specify a CSP name, Sn.exe clears the current setting.
-d container Deletes the specified key container from the strong name CSP.
-D assembly1 assembly2 Verifies that two assemblies differ only by signature. This is often used as a check after an assembly has been re-signed with a different key pair.
-e assembly outfile Extracts the public key from assembly and stores it in outfile.
-h Displays command syntax and options for the tool.
-i infile container Installs the key pair from infile in the specified key container. The key container resides in the strong name CSP.
-k outfile Generates a new key pair and writes it to the specified file.
-m [y|n] Specifies whether key containers are computer specific, or user specific. If you specify y, key containers are computer specific. If you specify n, key containers are user specific.

If neither y nor n is specified, this option displays the current setting.

-o infile [outfile] Extracts the public key from the infile and stores it in a .csv file. A comma separates each byte of the public key. This format is useful for hard coding references to keys as initialized arrays in source code. If you do not specify an outfile, this option places the output on the Clipboard.
-p infile outfile Extracts the public key from the key pair in infile and stores it in outfile. This public key can be used to delay sign an assembly using the /delaysign+ and /keyfile options of the Assembly Linker (Al.exe). When an assembly is delay signed, only the public key is set at compile time and space is reserved in the file for the signature to be added later when the private key is known.
-pc container outfile Extracts the public key from the key pair in container and stores it in outfile.
-q[uiet] Specifies quiet mode; suppresses the display of success messages.
-R assembly infile Re-signs a previously signed or delay signed assembly with the key pair in infile.
-Rc assembly container Re-signs a previously signed or delay signed assembly with the key pair in container.
-t[p] infile Displays the token for the public key stored in infile. The contents of infile must be previously generated using -p.

Sn.exe computes the token using a hash function from the public key. To save space, the common language runtime stores public key tokens in the manifest as part of a reference to another assembly when it records a dependency to an assembly that has a strong name. The -tp option displays the public key in addition to the token.

-T[p] assembly Displays the public key token for assembly. The assembly must be the name of a file that contains an assembly manifest.

Sn.exe computes the token using a hash function from the public key. To save space, the runtime stores public key tokens in the manifest as part of a reference to another assembly when it records a dependency to an assembly that has a strong name. The -Tp option displays the public key in addition to the token.

-v assembly Verifies the strong name in assembly, where assembly is the name of a file that contains an assembly manifest.
-vf assembly Verifies the strong name in assembly. Unlike the -v option, -vf forces verification even if it is disabled using the -Vr option.
-Vl Lists current settings for strong name verification on this computer.
-Vr assembly [userlist] [infile] Registers assembly for verification skipping. Optionally, you can specify a comma-separated list of user names. If you specify infile, verification remains enabled, but the public key in infile is used in verification operations. Assembly can be specified in the form *, strongname to register all assemblies with the specified strong name. Strongname should be specified as the string of hexadecimal digits representing the tokenized form of the public key. See the -t and -T options to display the public key token.
CAUTION   Use this option only during development. Adding an assembly to the skip verification list creates a security vulnerability. A malicious assembly could use the fully specified assembly name (assembly name, version, culture, and public key token) of the assembly added to the skip verification list to fake its identity. This would allow the malicious assembly to also skip verification.
-Vu assembly Unregisters assembly for verification skipping. The same rules for assembly naming that apply to -Vr apply to -Vu.
-Vx Removes all verification-skipping entries.
-? Displays command syntax and options for the tool.
Note   All Sn.exe options are case-sensitive and must be typed exactly as shown to be recognized by the tool.

Remarks

The -R and –Rc options are useful with assemblies that have been delay signed. In this scenario, only the public key has been set at compile time and signing is performed later when the private key is known.

Examples

The following command creates a new, random key pair and stores it in keyPair.snk.

sn -k keyPair.snk

The following command stores the key in keyPair.snk in the container MyContainer in the strong name CSP.

sn -i keyPair.snk MyContainer

The following command extracts the public key from keyPair.snk and stores it in publicKey.snk.

sn -p keyPair.snk publicKey.snk

The following command verifies the assembly MyAsm.dll.

sn -v MyAsm.dll

The following command deletes MyContainer from the default CSP.

sn -d MyContainer

See Also

.NET Framework Tools | Assembly Linker (Al.exe) | Strong-Named Assemblies

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