In order to use Segwit optimizations, you’ll need to use funds stored on a Segwit address which uses a different format — currently encoded as a multisigature (P2SH) address (starting with a 3 on Bitcoin mainnet)
You can access your new Segwit addresses or legacy addresses (where you will find your current funds) when starting the Bitcoin Wallet Chrome application (from v1.9.0). As Segwit migration is fully opt-in, you can continue to use only legacy addresses.
If you wish to upgrade, you can recreate the same account naming and structure on the Segwit branch, and move your funds from the legacy branch using Bitcoin transactions.
As upgrading to Segwit addresses helps providing more block capacity for every user, it’s definitely recommended to upgrade.
Note that the sender doesn’t need to upgrade — every wallet can natively send funds to a Segwit address.
Segwit addresses are available for Ledger Nano S with no firmware update and Ledger HW.1/Nano with a firmware update to version 1.0.3 required
Choosing the address type on Ledger Bitcoin Wallet
If you do not wish to use Segwit, or if you are not sure about anything, just click on the LEGACY button and you’ll access and manage your accounts as it was before.
Signature time optimization
When computing a Segwit signature, the previous transactions do not need to be processed by the device, and each input is only processed once during the signature process, leading up to a 60% time optimization in the signature process.
Using a Segwit address is definitely recommended if you plan to collect small transactions such as mining rewards
Segwit introduces the concept of block weight which changes the way the transaction size is computed by splitting the signatures in a different area — you can typically save 35% of the fee paid when sending a transaction immediately.
Segwit paves the way to multiple Bitcoin scripting optimization (through anti malleability and script versioning) — we’re closely monitoring progress on those different topics to let you use your Ledger Hardware Wallet with those innovations (such as the Lightning Network) as soon as possible.
