Quote from: Crowex on December 18, 2013, 01:42:49 AM

This seems along the lines of ECIES
http://en.wikipedia.org/wiki/Integrated_Encryption_Scheme

It is very much along those lines, yes.

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I'm not sure exactly how your system works but I would have thought it should be possible to use ECDH to create a shared secret without compromising your secret key and use this in a symmetric encryption scheme (AES) without compromising the shared secret? Isn't this basically what is done in ECIES?

Can you elaborate on this? The shared secret is rP where r is a random nonce in the prime field F/p and P is the public key point. This is never transmitted, rG is. I'm not sure I understand how this compromises the secret key?

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The private key is used in the creation of the shared secret but if this is done ok then using the shared secret in a secure symmetric system shouldn't compromise it in any way.

I may have misunderstood things but I don't see how the same private key is used for signing and encrypting - the shared secret used for encrypting isn't the private key of the bitcoin address is it??

The private key is not used in the creation of the shared secret since the person encrypting has only the public key and computes the shared secret through a nonce.

No, the shared secret used for encryption is not the same as the private key used to sign the bitcoin address.

I may not have understood gmaxwell correctly, but I thought this was still a potential vulnerability as the private key is still used for decryption?