HMAC-SHA-1 security question

Hi
I'd have an interesting question.

We know that HMAC-SHA 1 is a hash value H, computed from a base input
value V and a secret key K.
In formula: H = HAMC-SHA-1(K, V).

Now, let us assume an attacker knows H and V. Only the K is unknown.
I'd like to know if there was any possibility to make conclusions
about the secret key K?
Or, furthermore, do values for H and V exist that make it possible to
conclude about K? Even if it was just one bit one can make conclusions
about? Any ideas?

Please, I'd like to hear some input on this from somebody...
.

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