fn ec_key_ecdh()

in aws-lc-rs/src/agreement.rs [729:760]

• 25 lines of code
• 5 McCabe index (conditional complexity)

fn ec_key_ecdh<'a>(
    buffer: &'a mut [u8; MAX_AGREEMENT_SECRET_LEN],
    priv_key: &LcPtr<EVP_PKEY>,
    peer_pub_key_bytes: &[u8],
    nid: i32,
) -> Result<&'a [u8], Unspecified> {
    let mut pub_key = encoding::parse_ec_public_key(peer_pub_key_bytes, nid)?;

    let mut pkey_ctx = priv_key.create_EVP_PKEY_CTX()?;

    if 1 != unsafe { EVP_PKEY_derive_init(*pkey_ctx.as_mut()) } {
        return Err(Unspecified);
    }

    if 1 != unsafe { EVP_PKEY_derive_set_peer(*pkey_ctx.as_mut(), *pub_key.as_mut()) } {
        return Err(Unspecified);
    }

    let mut out_key_len = buffer.len();

    if 1 != indicator_check!(unsafe {
        EVP_PKEY_derive(*pkey_ctx.as_mut(), buffer.as_mut_ptr(), &mut out_key_len)
    }) {
        return Err(Unspecified);
    }

    if 0 == out_key_len {
        return Err(Unspecified);
    }

    Ok(&buffer[0..out_key_len])
}