ECC or RSA Cryptography Encoder/Decoder in C

Hi. I need a cryptography programmer who can code for me a highly sophisticated elliptic curve cryptography key generator (preferably using OpenSSL) which I can hash with SHA-256. If ECC is too complex, RSA may also be substituted as a replacement as I believe both of these methods use a public and private key. I already have the working SHA-256 hash code but I need someone to help me with the ECC or RSA code. The idea would be that we would hash the data and then sign the hash. This will prove that whoever generated this hash has the private key. Then you get the data that you want to verify, calculate the hash on it and then check that. If the calculated hash matches the one in the signature then the signature is valid. At this point we will have have high confidence that the data has not been changed and that it was generated by someone that has the private key. Important things to note are that you must code it in pure C (not C++). Thanks.