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Author Topic: How do you decompress a public key?  (Read 2340 times)
piotr_n
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April 09, 2013, 01:41:44 PM
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A compressed public key contains 02 or 03 at the fist byte, followed by 256-bits of the X.
https://en.bitcoin.it/wiki/Elliptic_Curve_Digital_Signature_Algorithm

How do you calculate the Y, out of it?

I see that the client just calls EC_KEY_set_conv_form with POINT_CONVERSION_COMPRESSED, but since I need to do it in an app which not use OpenSSL, could anyone please refer me to some doc/code explaining the math behind this process?

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April 09, 2013, 01:43:05 PM
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I don't believe that you can derive the uncompressed public key from just the compressed public key.  I'm pretty sure that you need the private key for that.

"The powers of financial capitalism had another far-reaching aim, nothing less than to create a world system of financial control in private hands able to dominate the political system of each country and the economy of the world as a whole. This system was to be controlled in a feudalist fashion by the central banks of the world acting in concert, by secret agreements arrived at in frequent meetings and conferences. The apex of the systems was to be the Bank for International Settlements in Basel, Switzerland, a private bank owned and controlled by the world's central banks which were themselves private corporations. Each central bank...sought to dominate its government by its ability to control Treasury loans, to manipulate foreign exchanges, to influence the level of economic activity in the country, and to influence cooperative politicians by subsequent economic rewards in the business world."

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April 09, 2013, 01:44:23 PM
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https://bitcointalk.org/index.php?topic=162805

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April 09, 2013, 01:45:29 PM
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Cheers!

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