Import a Public key from somewhere else to CngKey?

Question

I am looking for a cross platform way to share public keys for ECDSA signing. I had a great thing going from a performance perspective with CngKey and the standard .NET cry

Answer 1

You convert EC key to BCRYPT_ECCKEY_BLOB by like this. We should ignore the first byte from EC key because it just represent compressed/uncompressed format.

BCRYPT_ECCKEY_BLOB eccBlobHeader;
PCHAR bycrtptKey;
eccBlobHeader.dwMagic = BCRYPT_ECDH_PUBLIC_P384_MAGIC;  
eccBlobHeader.cbKey = 48;//size of EC key(without 1st byte)
memcpy(bycrtptKey, &eccBlobHeader, 8);//copying 8bytes header blob
memcpy(bycrtptKey+ 8,publicKeyFromOtherParty+1,publicKeyFromOtherPartySize- 1);

now use bycrtptKey for importing.