CSV stands for Check Sequence Verify for the Bitcoin scripting system. CHECKSEQUENCEVERIFY redefines the existing NOP3 opcode. It has made huge improvement in bitcoin protocols. Since a long time users are waiting for a fix for bitcoin transaction malleability. CSV seems to fix the issue and provide much faster payments in transactions now. Pieter Wuille who is core tech engineer in Blockstream with Eric Lombrojo( co-CEO of Ciphrex) and Johnson Lau published new version of segwit. It is the fourth and probably last version of the soft fork Segregated Witness.It is published by them with an aim to increase the flexibility of bitcoin transaction. It can also be mentioned as “SegNet 4”.
CheckSequenceVerify (CSV) is included in SegNet 4. CSV is a big improvement in bitcoin protocol. CSV allows users to prevent selected inputs getting confimred for a certain amount of time. As a result after this period of blockage of coins, the coins will be unlocked for transaction. It is set to improve the Bitcoin protocol. For example-a long-awaited fix of transaction malleability.
It is quiet similar to CLTV (CheckLockTimeVerify) which can allow a user to make bitcoins unspendable for a period of time. But CSV is quiet different to CLTV. The main difference between them is that CLTV locks coins until a specified moment in time whereas CSV lock is relative and applies only after the transaction is included in a block. As a result CSV implementation gives more flexibility in transactions. This is useful for Payment Channels which are great for micropayments or for fast payments.
Eric Lombrojo mentioned about the combination of Segregated Witness and CSV particularly benefits added scaling layers on top of the Bitcoin blockchain in a bitcoin magazine interview.
SegNet 4 effectively adds block space, and provides added layers like the Lightning Network. (The lightning network extends the bidirectional payment channel idea to allow for payments to be routed over multiple bidirectional payment channel hops).
“SegNet 4 offers a testing environment for routable bidirectional payment channels such as the Lightning Network or Amikopay,” Lombrozo told Bitcoin Magazine.
“These projects could drastically increase Bitcoin’s scalability, and allow for instant secure and cheap payments. With SegNet 4, we’re providing a common network on which different projects can collaborate and test their ideas. It is open for anyone, and we’re encouraging wallet developers to play around with it.” Said Lombrozo.
In terms of developers CSV is a “soft fork.” which means that after implementation, only miners would be required to undergo immediate software upgrade.There is no problem for other users, they can join any time whenever they want with no risk of being disconnected from the network.It is the main advantage of CSV and SegNet4.
Also now Bitcoin protocol allows soft forks to be rolled out more easily and faster than before, which should benefit Segregated Witness activation as well.
Lombrozo said: “We’re using BIP9 for activation, which means we can deploy CSV and Segregated Witness in parallel; Segregated Witness won’t have to wait for CSV activation nor vice versa.
Below are the thing which are required for the successful CSV Activation :
1.95% of the blocks support it on block explorers, for it to activate.
2.Out of the 2016 blocks , only up to a maximum of 100 blocks can be non CSV.
CSV activation can happen in about 13 days or less if the above two conditions are satisfied.
Credit must also be given to the Mark Friedenbach who invented the application of sequence numbers to achieve relative lock-time, and wrote the reference implementation of CHECKSEQUENCEVERIFY.