Adam Back，他的twitter頁面介紹為，賽博朋克，密碼學家，隱私保護/電子現金，Hashcash（被用作比特幣挖礦）發明人，電腦科學博士，Blockstream聯合創始人兼CEO。
正如他的標籤提到的，Hashcash是比特幣白皮書引用不多的內容之一，Adam Back的名字被寫入了比特幣白皮書，工作量證明也成為了比特幣的基石。（這篇文章講述了Adam Back是如何推動比特幣誕生的）
2014年，Adam back在美國舊金山創辦了Blockstream，聘請了幾位比特幣核心開發者，持續推動比特幣和區塊鏈技術的發展與應用。
站在比特幣白皮書釋出十年的節點上，我們訪問了Adam Back，話題包括這幾年來比特幣的技術演進，閃電網路，側鏈，保密交易等技術進展，未來可能突破的技術方向，Adam還展望了比特幣的未來，他認為比特幣正處於新技術的接納階段，就像網際網路，手機最初被採用那樣。而未來十年將會更有趣，因為我們會看到比特幣被廣泛採用，眾多新應用程式和用途被開發。
以下為訪談全文：
8btc：從比特幣的誕生到現在，你認為比特幣在技術演進上經歷了哪些關鍵節點？有哪些技術突破？Since the creation of bitcoin, are there any key points about technology evolution you can think of? Any important technology breakthroughs?
Adam Back：這些年來，比特幣在程式碼效率、可擴充套件性及網路協議（同步速度量級提升）等方面都有了巨大的進步，還有著許多可用性的改進，包括HD錢包（更容易備份）、P2SH（可以傳送至接收者選擇的複雜指令碼，並在傳送時段保持公開)等。我認為雙向支付通道（Decker和Wattenhofer）和閃電網路 （Poon和Dryja） 給比特幣提供了巨大的可擴充套件性優勢，同時也提供了速度更快、成本更低的零售支付及微支付方式——比特幣很棒了，但我們希望所有對它感興趣的人們都能夠使用它，所以可擴充套件性很重要！There have been huge improvements over the years in Bitcoin’s code efficiency, scalability and network protocol (orders of magnitude faster sync) as well as many usability improvements, including HD Wallets (easier to backup), P2SH (ability to send to complex scripts chosen by recipient to be disclosed at spending time). I think duplex payment channels (Decker and Wattenhofer) and Lightning (Poon and Dryja) offer huge scalability advantages while providing faster, cheaper retail payments as well as enabling micropayments - Bitcoin is great but we would like everyone interested to be able to use it, so scalability is important!
8btc：哪些技術是重要的，值得肯定的？另一方面，我們有沒有走一些彎路？Can you give us examples of some useful/important technologies? On the other side, did we make any mistakes?
Adam Back：早期比特幣存在著較多漏洞，但那些明顯的漏洞似乎大多已經被修復了。儘管經過了更加嚴格的開發和審查過程，但軟體依然是複雜的，有些漏洞仍然不容易被發現和修復完善。 In the early days of Bitcoin there were some more major bugs, but the shallow bugs seem to be mostly fixed. However despite overtime more rigorous development and review processes, software is complex, and some bugs are still though infrequently discovered, and carefully fixed.
8btc：比特幣以後會不會有硬分叉擴大區塊的計劃？還是隻會專注於其它的技術方案，例如閃電網路、側鏈這些layer 2 方案？Will bitcoin go through a hard fork to increase the blocksize? Or layer-2 technologies like lightning network, sidechain are our only ways to solve this kind of problem?
Adam Back：我認為長遠看來，隨著技術的進步，更緊湊的交易將變得可能，如schnorr聚合簽名及未來的其他創新等，將可以更有效地使用區塊空間。因為比特幣基礎層是一種廣播機制，所以在驗證成本間總是存在著權衡，為了讓比特幣能夠成為P2P網路和承載網路，使企業和高階使用者能夠同步和驗證它的區塊鏈是非常重要的。然而，隨著技術和網路容量的提高，其效率和規模都可能透過某種機制得到提高。 I think longer term as technology improves more compact transactions become possible, like schnorr aggregated signatures, and other innovations in the future, allow more efficient use of block-space. Because Bitcoin base layer is a broadcast mechanism there is always a tradeoff between cost of validation, where in order for Bitcoin to be p2p and bearer, it is important that businesses and power users be able to sync and validate the chain. However as technology and networking capacity improves it maybe that both efficiency and size increases via some mechanism.側鏈並不是真正的可擴充套件性解決方案，因為它們有類似的權衡，高階使用者需要能夠驗證區塊鏈來使其有意義地成為一條可公開審計的區塊鏈。 側鏈更多的，是為特定的用例引入那些對比特幣主鏈來說可能沒有意義的新功能，或者這些功能也可以先在側鏈上進行嘗試，然後再新增到比特幣中。 Sidechains are not really a scaling solution as they have a similar tradeoff where power users need to be able to verify the chain for it to meaningfully be a publicly auditable blockchain. Sidechains are more about introducing new features for specific use cases that may not make sense for the main Bitcoin chain, or that can be tried first on a sidechain and may be later added to Bitcoin.
閃電網路及其他layer 2解決方案為可擴充套件性提供了非常好的權衡，透過閃電網路的一些權衡改進，使得其數量級和規模能比在鏈上進行公開審計的更加的大。 Lightning and other 2nd layer solutions offer a hugely better tradeoff for scalability, with Lighning via some trade-offs, being able to provide many orders of magnitude more scale, than would be plausibly publicly audited on-chain.
8btc：能否介紹一下閃電網路和側鏈技術方案的進展？Can you tell us about the progress of lightning network and sidechain?
Adam Back：閃電網路似乎進展得非常快，有著眾多的駭客馬拉松、眾多獨立實現（c-lightning、LND和eclair）、獨立協議開發者及眾多錢包，還有非常活躍的閃電網路應用開發者對其感興趣。 The lightning network seems to be progressing very rapidly with many developer hackathons, multiple independent implementations (c-lightning, LND and eclair), independent protocol developers and multiple wallets and very active Lightning application developer interest.側鏈方面也在積極開展工作，Blockstream為比特幣交易所清算服務的Liquid網路已經推出上線，且支援更加保密、更加快速的清算和流動資產支援。Liquid使用聯盟信任模型來降低交易中的託管風險。此外，包括Drivechain和RootStock等，側鏈的變體和概念還在不斷改進。 There is active work on sidechains, with Blockstream’s Liquid network for Bitcoin-exchange settlement now being live and enabling more confidential, faster settlement, and Liquid Asset support. Liquid uses a federated trust model to reduce custody risk from trading. Also there is ongoing work on improving sidechain variants and concepts including drivechain, and rootstock.
8btc：我們該如何看待軟體安全漏洞，例如近期發生的core軟體漏洞事件？We know that Bitcoin Core client had a severe bug recently, which was already fixed. How should we deal with software bugs in the future?
Adam Back：軟體開發是人類工作最複雜的領域之一。類似飛機系統，比特幣開發在開發審查和測試方面採取了非常謹慎的方法。當發現漏洞時，就像飛機事故一樣會進行事後分析，以確定原因及審查修改程式，吸取教訓來防止類似問題再次發生。 Software development is one of the most complex areas of human undertaking. Like aircraft systems, Bitcoin development takes a very cautious and careful approach to development review and testing. When bugs are discovered, like with aircraft incidents, a post-mortem is done to determine the causes and processes reviewed and amended to try to draw lessons and prevent a similar issue recurring.
8btc：由Blockstream聯合斯坦福大學、倫敦大學學院提出的Bulletproofs技術方案，已經在門羅幣上得到了應用，那這種技術是否會應用到比特幣的身上呢？如果可以的話，優缺點在哪？Bulletproofs is developed by Blockstream, Stanford university and University College London. It is implemented in Monero network. Do you think bitcoin can be adopted this tech? If so, what are the advantages and disadvantages?
Adam Back：就我個人而言，我希望看到比特幣最終能實現保密交易。目前保密交易已經可以在Liquid側鏈和相關FOSS專案中實現使用。上述研究機構的研究人員進行調查期間，為了進一步最佳化保密交易使用的範圍證明（range proofs），Bulletproofs技術便出現了。 Personally I would be interested to see Confidential Transactions implemented in Bitcoin eventually. Already today CT is available for live use in the Liquid sidechain and the associated Elements FOSS project. BulletProofs arose during an investigation by researchers at the mentioned research institutions to further optimise the range proofs used by Confidential Transactions.實際上，除了為保密交易提供更緊湊和更符合對數縮放的範圍證明之外，Bulletproofs還是執行的通用簽名，能夠證明程式的執行，類似於SNARKs，但其具有更健壯的保守安全保證。Bulletproofs及其他技術的進一步最佳化，對比特幣和區塊鏈的最佳化來說可能有著有趣的應用。特別是執行遞迴證明的前景非常有趣，因為程式會是另一個程式的直譯器。 In fact as well as providing a more compact and log-scaling range-proof for CT, BulletProofs are a general signature of execution able to make proofs of program execution, similar to SNARKs but with more robust conservative security assurances. BulletProofs, and further optimisation of them may have interesting applications for Bitcoin and blockchain optimisation. Particularly the prospect of recursive proofs of execution is interesting, where the program is an interpreter for another program.
8btc：對於可能替代Merkle tree資料結構的RSA累加器方案，斯坦福大學的Benedikt Bünz提出說透過這種方案可以有效壓縮比特幣區塊鏈的UTXO集大小，另外以太坊創始人Vitalik也在研究這種資料結構，這種方案能否應用到比特幣身上呢？如果可以的話，預計效果會怎樣？Proposed by Benedikt Bünz from Standford University, RSA accumulators can replace Merkle tree by compressing bitcoin UTXO. Ethereum’s founder Vitalik also pays a lot attention on this solution. Do you think it can be adopted on bitcoin? If so, what can it do for bitcoin?
Adam Back：RSA累加器的權衡之處是，其安裝過程中必須刪除一個主私鑰。所以我個人認為，在“去信任驗證”的比特幣中很難使用這一方案。RSA累加器是一個有趣的技術機制，其來源可以追溯至1993年Benaloh的論文。在zeroCash的白皮書中也對其進行了探討以構造零知識身份證明。 A trade-off with RSA accumulators is that there is a master private key that must be deleted during setup. So personally I think it is difficult to use that in Bitcoin which has a “Don’t Trust. Verify” approach. RSA accumulators are an interesting technical mechanism dating back to Benaloh’s 1993 paper. They were also explored in the zeroCash paper, to construct zero-knowledge set membership proofs.
8btc：對於以太坊2.0 的分片+Casper+Plasma 發展計劃，您有什麼看法？What do you think of Ethereum 2.0? i.e. sharding+Casper+Plasma.
Adam Back：我並沒有真正地去追蹤很多相互競爭的共享系統，因為現在有這麼多的共享系統，而且我認為比特幣的安全性及其以效率為中心的分層方式更有希望。 I don’t really track the many competing shares systems as there are so many, and I see more promise in Bitcoin’s security and efficiency focussed approach with layers.
8btc：對於區塊鏈的安全、去中心化以及效率的“不可能三角”猜想您是怎麼看的？有些團隊認為可以打破這個猜想，您覺得可能嗎？There’s a theory known by blockchain community named ‘impossible triangle’. It means that a blockchain system cannot have security, decentralization and effectiveness simultaneously. You can only get two of them and abandon the other one. What do you think of this theory? Some blockchain projects think they can break this ‘curse’, do you think it is possible for them to do so?
Adam Back：我想我們需要一些新的BulletProof/ SNARK之類的創新來打破這個不可能三角。就我至今所見，還沒有人能既保留工作證明激勵保障機制，又保留比現有的比特幣模型更好的完整驗證模型。這並不是要否定研究，但它反映出這是一個棘手的問題，且人們往往會低估自己所做的權衡折衷。 I think we will need some new BulletProof / SNARK like innovations to break this triangle. From what I have seen so far no one has retained proof-of-work incentive security, and retained a full-validation model with better than the existing Bitcoin model. This is not to dismiss research, but reflects that this is a hard-problem and people tend to discount the trade-offs they have made.
8btc：現在的比特幣開發社羣是怎樣的？跟最開始的時候有哪些關鍵區別？普通人能否參與其中呢？What does bitcoin developer community look like now? Any difference between the earliest one and nowadays? Can an ordinary person join this community?
Adam Back：據我所知，現在你可以在發行版名單上看到有數百名開發者。許多早期的開發者們仍然非常活躍，也有一些新的開發者也加入了進來。當然，許多方面我們都可以加入並提供幫助，包括撰寫文件、測試、教育和學習其協議及其程式碼，還有應用程式開發、構建用例和培訓使用者等方面。同時還有一些開發者培訓計劃和行業/開發者最佳實踐計劃等。 From what I hear there are now hundreds of developers that you can see listed on releases. Many of the early developers are still very active, and some new active developers have joined. There is certainly scope to join in and help in many ways, including documentation, testing, education and learning the protocols and code. As well as application development, building use-cases, and training users. There are several developer training programs and industry / developer best practices initiatives at this point also.
8btc：站在比特幣十年的節點上，你對未來有什麼預測或展望？Bitcoin has gone through ten years since its birth, what predictions you can make for its future? Or can you tell us how it will develop in the future? You can talk about price, possible applications and technology developments, etc..
Adam Back：就我個人而言，我希望能看到比特幣的可替換性得到改善，還有比特幣協議和節點軟體的每一個主要發行版中都能有一些能提高隱私保護的增量內容，比如schnorr簽名、taproot、閃電網路layer2支付提供的dandelion等相關協議。我還希望能看到更多有雄心的方法，比如經驗證和最佳化的保密交易等方法最終以各自的方式融入比特幣。 Personally I would like to see fungibility improved, and there are incremental things that improve privacy in each major release of the Bitcoin protocol and node software, like schnorr signatures, taproot and related protocols, dandelion as well as the privacy provided by Lightning layer2 payments. I would also like to see more ambitious approaches like Confidential Transactions validated and optimised more eventually make their way into Bitcoin.很難說價格會怎麼樣，但在我看來，比特幣似乎仍處於新技術的接納階段，正如網際網路、手機最初被採用那樣。在某種程度上，對於那些看重比特幣所提供的獨特用例的人來說，比特幣將達到其應用S曲線的頂端，成為抗審查的電子貨幣，或其希望持有比特幣，將其作為一種資產類別與黃金競爭：比特幣有一些類似黃金的屬性，但與實物黃金相比有很多優勢。一些人正進一步計劃實現超級比特幣化( hyperbitcoinization)，給各國貨幣帶來競爭，特別是對於那些存在惡性通貨膨脹或其他貨幣問題的國家。但就我個人而言，我認為，如果比特幣與黃金競爭，那就已經非常有趣了，根據對實物黃金私人擁有量的估計，已經可以設想其價格的顯著上漲。我們將會看到接下來會發生什麼。接下來的10年應該會很有趣，因為我們會看到其被廣泛接納采用、還有眾多新應用程式及用途被開發。 It’s hard to say what price will do, but to me it does seem like Bitcoin is still in the adoption phase of new technology as Internet use, mobile phones saw in their initial adoption. At some point Bitcoin will reach the top of it’s adoption S curve for people who value the unique use-cases Bitcoin offers, as the censor resistant electronic money, or wish to hold Bitcoin as an asset class competing with gold: Bitcoin has some similar properties but a number of advantages vs physical gold. Some people are projecting further out to hyperbitcoinization providing competition to national currencies, particularly in countries with hyperinflation or other monetary problems. But personally I think it’s already interesting if Bitcoin competes with gold which already envisages significant price growth depending on estimates of the private ownership of physical gold. We’ll see what happens after that. The next 10 years should be interesting as we see adoption play out and new applications and uses develop.
感謝思敏，Linkea，灑脫喜，Wendy對此次訪談做出的貢獻。
