LTK is the Long term key stored in the device, that is exchanged after bonding. In the Legacy pairing the slave device just picks a random LTK and sends it over to the master. In LE Secure Connections the LTK is derived from a diffie hellman exchange.
The LL_ENC_REQ and LL_ENC_RSP packets contain "session key diversifiers" and not the LTK (since that would kind of destroy the security if the key was sent in cleartext before encryption was enabled). In order to make each new connection secure, a new session key is used for every connection. To create this session key, each device generates 8+4 bytes random data. The SKDm and SKDs values are concatenated to a 16 byte SKD. The session key is generated by AES-ECB-encryption using the LTK as key and SKD as plaintext. Note that after concatenating SKDm and SKDs, reverse all whole 16 bytes before you input it to a standard AES function, since Bluetooth uses little endian but the AES standard uses big endian.
So 487E4174426ACC34A83103763D2D95BE is your SKD on the format expected by all AES libs.
The Rand and EDIV fields in the LL_ENC_REQ are sent to the slave as identifier to the key so it can look the LTK up in its database.
The IVm and IVs value should be concatenated to get IV (not reversed). This IV is used as part of the nonce in the AES-CCM encryption. See Bluetooth Core Specification 5.0, Vol 6, Part E, Chapter 2.1.
