i wonder why a server without any FS can get an A- while a aerver with FS but weak 1024bit DH Key only can get a B. Does this make sense ? A Server without FS should get lower rating than one with weak FS, isn't it ?
No, because decrypting weak DHE is much easier than decrypting strong RSA. Once you've decrypted an RSA private key you can decrypt any and all traffic secured with a TLS_RSA* cipher suite, but weak DHE allows you to decrypt client connections on the fly without needing to know the strong RSA private key.
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