Blasphemy is an anglicized form of the Greek term
blasphemia derived from two roots,
blapto, to injure, and
pheme, to speak.
The word would thus suggest injurious speech.
I love etymology! It tells us so much.
I always thought that blaspheming the HS would be to reject his calling. Which in turn would leave one 'unsaved' thus that can't be forgiven because a gift was offered but rejected, thus Yeshua rejected.
However if it is actually a spoken thing I would agree that it would be giving credit to the Adversary for that which G-d alone deserves the credit.
Reminds me of this
8And the four beasts had each of them six wings about
him; and
they were full of eyes within: and they rest not day and night, saying, Holy, holy, holy, Lord God Almighty, which was, and is, and is to come.
9And when those beasts give glory and honour and thanks to him that sat on the throne, who liveth for ever and ever,
10The four and twenty elders fall down before him that sat on the throne, and
worship him that liveth for ever and ever, and cast their crowns before the throne, saying,
11Thou art worthy, O Lord, to receive glory and honour and power: for thou hast created all things, and for thy pleasure they are and were created.
Proper worship, credit where credit is due. 
L-RD G-D
