sgx_tdh/src/ecp.rs

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use sgx_types::*;
use sgx_tcrypto::*;


pub const EC_LABEL_LENGTH: usize = 3;
pub const EC_SMK_LABEL: [u8; EC_LABEL_LENGTH] = [0x53, 0x4D, 0x4B];
pub const EC_AEK_LABEL: [u8; EC_LABEL_LENGTH] = [0x41, 0x45, 0x4B];
pub const EC_DERIVATION_BUFFER_SIZE: usize = 7;

pub fn derive_key(shared_key: &sgx_ec256_dh_shared_t,
                  label: &[u8; EC_LABEL_LENGTH]) -> SgxResult<sgx_ec_key_128bit_t> {

    let cmac_key = sgx_cmac_128bit_key_t::default();
    let mut key_derive_key = try!(rsgx_rijndael128_cmac_msg(&cmac_key, shared_key).map_err(set_error));

    //derivation_buffer = counter(0x01) || label || 0x00 || output_key_len(0x0080)
    let mut derivation_buffer = [0_u8; EC_DERIVATION_BUFFER_SIZE];
    derivation_buffer[0] = 0x01;
    derivation_buffer[1] = label[0];
    derivation_buffer[2] = label[1];
    derivation_buffer[3] = label[2];
    derivation_buffer[4] = 0x00;
    derivation_buffer[5] = 0x80;
    derivation_buffer[6] = 0x00;

    let result = rsgx_rijndael128_cmac_slice(&key_derive_key, &derivation_buffer).map_err(set_error);
    key_derive_key = Default::default();
    result
}

fn set_error(sgx_ret: sgx_status_t) -> sgx_status_t {

    let ret = match sgx_ret {
        sgx_status_t::SGX_ERROR_OUT_OF_MEMORY => sgx_status_t::SGX_ERROR_OUT_OF_MEMORY,
        _ => sgx_status_t::SGX_ERROR_UNEXPECTED,
    };
    ret
}