Alright, I've made it work now. What a nightmare. I'll document my findings here for future reference.
- External manifest files are cached in a hidden, unflushable cache. If you update a manifest, Windows will silently ignore all changes and use the old version instead. The only reliable way to actually make it read the new manifest is to change the modified date property on the application exe.
- Some blowfish.dlls have an embedded manifest that overrides the external, some don't.
- Using the same name for the assemblyIdentity and the DLL can cause conflicts.
In the end, I used the blowfish.dll with manifest from the ts-patches git dkeeton linked (filesize 160768), and these two manifests in the RA2 folder:
game.exe.manifest:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
<assemblyIdentity
type="win32"
name="client.exe"
version="1.0.0.0" />
<dependency>
<dependentAssembly>
<assemblyIdentity
type="win32"
name="blowfish.sxs"
version="1.0.0.0" />
</dependentAssembly>
</dependency>
</assembly>
blowfish.sxs.manifest:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
<assemblyIdentity
type="win32"
name="blowfish.sxs"
version="1.0.0.0" />
<file xmlns="urn:schemas-microsoft-com:asm.v1" name="BLOWFISH.DLL" hashalg="SHA1">
<typelib tlbid="{E7F91750-8861-11D1-B707-00A024DDAFD1}" version="1.0" helpdir="" flags="HASDISKIMAGE"></typelib>
<comClass clsid="{1440AD10-6AA8-11D1-B6F9-00A024DDAFD1}" tlbid="{E7F91750-8861-11D1-B707-00A024DDAFD1}" description="Blowfish encryption algorithm"></comClass>
</file>
<comInterfaceExternalProxyStub name="IBlockCipher" iid="{E0113100-6A7C-11D1-B6F9-00A024DDAFD1}" tlbid="{E7F91750-8861-11D1-B707-00A024DDAFD1}" proxyStubClsid32="{E0113100-6A7C-11D1-B6F9-00A024DDAFD1}"></comInterfaceExternalProxyStub>
</assembly>
Some of that might or might not be redundant, but at least it works now without Administrator rights and COM registration.
