ng5000 ng5000 - 1 year ago 57
C# Question

How to fix "Referenced assembly does not have a strong name" error?

I've added a weakly named assembly to my Visual Studio 2005 project (which is strongly named). I'm now getting the error:

"Referenced assembly 'xxxxxxxx' does not have a strong name"

Do I need to sign this third-party assembly?

Answer Source

To avoid this error you could either:

  • Load the assembly dynamically, or
  • Sign the third-party assembly.

You will find instructions on signing third-party assemblies in .NET-fu: Signing an Unsigned Assembly (Without Delay Signing).

Signing Third-Party Assemblies

The basic principle to sign a thirp-party is to

  1. Disassemble the assembly using ildasm.exe and save the intermediate language (IL):

    ildasm /all / thirdPartyLib.dll 
  2. Rebuild and sign the assembly:

    ilasm /dll /key=myKey.snk

Fixing Additional References

The above steps work fine unless your third-party assembly (A.dll) references another library (B.dll) which also has to be signed. You can disassemble, rebuild and sign both A.dll and B.dll using the commands above, but at runtime, loading of B.dll will fail because A.dll was originally built with a reference to the unsigned version of B.dll.

The fix to this issue is to patch the IL file generated in step 1 above. You will need to add the public key token of B.dll to the reference. You get this token by calling

sn -Tp B.dll 

which will give you the following output:

Microsoft (R) .NET Framework Strong Name Utility  Version 4.0.30319.33440
Copyright (c) Microsoft Corporation.  All rights reserved.

Public key (hash algorithm: sha1):

Public key token is a8a7ed7203d87bc9

The last line contains the public key token. You then have to search the IL of A.dll for the reference to B.dll and add the token as follows:

.assembly extern /*23000003*/ Eurolook.Common
  .publickeytoken = (A8 A7 ED 72 03 D8 7B C9 )                         
  .ver 10:0:0:0
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