How Bitcoin Custody Works & Breaking Down The Coldcard Incident

SecP256K1 是公开的。

SecP256K1 is public.

每个地址的余额都是公开的。

Every address balance is public.

每一笔交易记录都是公开的。

Every transaction that's ever been made is public.

BIP 39 单词列表，也就是构成你助记词的那些单词，也是公开的。

The BIP 39 word list, like what your the words that make up your seed phrases are public.

你上次交易时的签名是公开的。

The signature on your last spend is public.

你的币进入钱包的那个区块是公开的。

The block your coins arrived into your wallet is public.

签名算法是公开的。

The signature algorithm is public.

SHA256 是公开的。

SHA256 is public.

交易图是公开的。

The transaction graph is public.

内存池是公开的。

The mempool is public.

除了一个东西，你的根密钥，其他一切都是公开的。

Everything is public except one thing, your root secret.

就这么简单，各位。

That's it, guys.

存储比特币的全部意义就在于此。

That's all storing Bitcoin is.

我不想对懂技术的人过度简化，但为了让大家都明白，存储比特币就是这么回事。

Now I don't you know, for the technical, I don't wanna over over oversimplify it, but just for everyone to understand, that's all storing Bitcoin is.

当你生成一个钱包时，你实际上是在生成一个根密钥。

When you generate a wallet, you're generating one root secret.

这个根密钥决定了你是否能签名并转移比特币。

And that one root secret defines whether you can sign and move Bitcoins or not.

因为这才是真正拥有钱的意义，而不是把它挂在墙上看着。

Because that's what ownership of money really is, not to stare at it on a wall.

如果必要的话，你能花掉它吗？

If you had to, could you spend it?

就这么简单。

And that's it.

一切都归结于这一个根密钥。

It all comes down to this one root secret.

那我们就来聊聊这个密钥。

So let's get into the secret.

好吗？

Okay?

为什么一个随机数就能保护一个公开的系统？

Why one random number can secure a public system?

这到底是怎么做到的？

How the hell is that even possible?

好。

K.

再说一遍，技术部分请多包涵。

Again, bear with me on the technical stuff here.

如果太技术了，你们会在YouTube评论区留言的。

If it gets too technical, you guys will leave comments in the YouTube section.

你们会提问。

You'll ask questions.

迪伦在直播聊天里，我会回答。

Dylan's in the live chat, and I'll answer.

可能这期，可能下期，但我们一定会讲到。

Maybe this episode, maybe next episode, but we will get there.

我向你保证。

I promise you.

好吗？

Okay?

但请耐心听我说。

But bear with me.

当人们谈论比特的时候。

When people talk about bits.

明白吗？

Okay?

比如比特币私钥或者冷钱包的漏洞。

Like a Bitcoin private key or or or cold cards bug.

有多少比特的熵？

How how many bits of entropy?

这个分解起来会很有趣，因为它其实比你想象的要简单。

This is gonna be really fun to break down because it's actually more simple than you think.

一个比特就是一个二进制选择。

One bit is one binary choice.

明白吗？

Okay?

所以一个比特，就是0或1。

So one bit, zero or one.

明白吗？

Okay?

那就是两种可能的结果。

That's two possible outcomes.

对吧？

Okay?

一个比特有多安全？

How secure is one bit?

其实不太安全，因为人就能轻松处理完所有可能的结果。

It's not very secure, because it takes a human to be able to to chew through the amount of potential outcomes.

只有两种。

There's only two.

结果要么是0，要么是1。

The outcomes are either zero or one.

这非常二元化。

It's very binary.

那么假设我们从一位增加到两位。

So let's say we increase from one bit to two bits.

好，现在有四种可能的结果。

Well, now there's four possible outcomes.

因为可能的结果现在是零零、零一、一零或一一。

Because the possible outcomes are now either zero zero, zero one, one zero, or one one.

刚才那个洞察非常关键。

Very critical insight that just happened right there.

从一位增加到两位，结果数量翻了一倍。

By going from one bit to two bits, we doubled the amount of outcomes.

翻倍了。

Doubled.

那如果我们增加到三位呢？

Now what if we went to three bits?

现在我们有八种可能的结果。

We now have eight possible outcomes.

我没有把它们写在幻灯片上，但就是000或者001。

And I didn't write them on the slide, but it's zero zero zero or zero zero one.

对吧？

Right?

以此类推。

And and so on and so forth.

关键在于，每增加一个比特，并不是只增加一种可能性。

Now the point is each new bit does not just add a possibility.

而是让整个可能性空间翻倍。

It doubles the entire space of possibilities.

你们明白这个意思吗？

Do you guys understand that?

所以，从一位开始。

So you go one bit.

一个比特就是二进制的，大家明白吧。

A bit it's very binary, guys.

一个比特要么是0，要么是1。

A bit's either zero or one.

所以如果你只有一个比特的安全熵，那根本谈不上安全，因为我猜都能猜到。

So if you have one bit of entropy of security, well, that's not secure at all because I can guess it.

是0吗？

Is it zero?

不是？

No?

好。

Okay.

那就是1。

Then it's one.

搞定。

Boom.

你的比特币在我手里了。

I have your Bitcoins.

好的。

Okay.

我们来增加熵值。

Let's increase the entropy.

两个比特。

Two bits.

两个比特就是四种可能。

Well, two bits now is four.

所以可能的结果数量翻倍了。

So we're doubling the amount of potential possible outcomes.

三个比特，八种可能。

Three bits, eight.

以此类推，一直这样下去。

So on and so forth, so on and so forth.

所以每增加一个随机比特，搜索空间就翻倍。

So every random bit doubles the search space.

明白吗？

Okay?

你可以把它想象成抛硬币。

So think of it like flipping a coin.

我右边展示的就是这个。

That's what I have here on the right.

要么正面，要么反面。

It's either heads or tails.

那么只抛一次有多安全呢？

So how secure is flipping once?

其实不太安全。

Well, not very secure.

抛两次的话，结果数量就翻倍了，因为可能是正正、反反、正反、反正这四种情况。

Flipping twice doubles the amount of outcomes because it could either be heads, heads, tails, tails, heads, tails, or tails, heads.

现在如果你抛三次，就有八种可能的结果。

Now if you flip it three times, there's eight potential outcomes.

四次的话是十六种，五次是三十二种，六次是六十四种，以此类推，以此类推，以此类推。

Four times, sixteen, five, 32, six, sixty four, so on and so forth, so on and so forth, so on and so forth.

所以当有人说260 256，不好意思，256位，你现在明白那是什么意思了吗？

And so when someone says 260 256, excuse me, 256 bits, Do you understand what that now means?

就是256个要么是0要么是1的位。

There's 256, either zero or ones.

而我在幻灯片上展示的是，每一个随机位都会让搜索空间翻倍。

And what I have here on the slide is every random bit doubles the search space.

关键词是随机。

Keyword random.

显然，如果我创建了256个0或1，但我说，前一半全是0，后一半全是1，那很容易猜出来，因为这不是随机的。

Obviously, if I create, you know, two hundred and fifty six zero or ones, but I say, you know, I'm gonna make the first half zero and the second half ones, that's very easy to guess because it's not random.

它必须是真正随机的。

It has to be truly random.

这里的目标是创造尽可能大的空间。

And the goal here is to create the largest amount of possible space.

有道理。

Makes sense.

因为我们需要做的是创造一个表面积如此巨大的东西，以至于在这个宇宙中，所有可能的结果都无法被穷举出来，从而找到我们的秘密。

Because what we need to do is create something with a surface area so large that all of the possible outcomes would be impossible to chew through in this universe to actually arrive and find our secret.

对吧？

Okay?

所以，如果继续往下讲，我想花点时间说明一下，因为256这个数字对人类来说听起来并不大。

So if I keep going, I wanna take a second now because the number 256 doesn't sound big to the human mind.

人类会觉得，嗯，256？

The human mind's like, well, 256?

我是说，那也不算大。

I mean, that's not that big.

而且我知道它后面的数字是什么。

And I know the number that comes after that.

那是257。

That's 257.

人脑其实根本无法理解这些数字有多大。

The human brain cannot actually comprehend the size of these numbers.

所以我想问一下，你看到下面那个256了吗？

So I wanna see do you see the 256 down there?

下面有个10的77次方。

There's 10 to the 77 down there.

好的。

Okay.

所以在这张幻灯片上，我做的就是，那是256的基数。

So what I did on this slide, that's so two that's 256 base.

明白吗？

Okay?

在这张幻灯片上，我做的就是，我说，好的。

What I did on this slide is I said, okay.

好，我们来看看10的6次方、10的9次方、10的12次方。

Well, let's take 10 to the six, ten to the nine, ten to the 12.

对吧？

Okay?

也就是一百万、十亿、一万亿。

Which is a million, a billion, a trillion.

明白吗？

Right?

为了让大家理解这些数字有多大，你们知道一百万秒之前是多久以前吗？

Just to comprehend how big these numbers are, do you guys know how long ago a million seconds ago was?

我只是想让大家更直观地感受一下，从10的6次方到10的9次方再到10的12次方，这个跨度有多大。

I'm just trying to humanize, you know, the size of going from 10 to the six to 10 to the nine to 10 to the 12.

你们有概念吗？

Do you guys have any idea?

一百万秒之前，大概是大概一个半星期以前。

A million seconds ago was about a week and a half ago.

对吧？

Okay?

那十亿秒之前呢？

How about a billion seconds ago?

那是多久以前？

How long ago was that?

是不是大概一个月前，或者一个季度前？

Was that, like, a month ago or a quarter ago?

不是。

No.

那是三十二年前。

That was thirty two years ago.

明白吗？

Okay?

所以一百万和十亿之间的差距是巨大的。

So the difference between a million and a billion is massive.

对吧？

K?

从一周半变成了三十二年。

It goes from a week and a half to thirty two years.

顺便说一句，我今年三十二岁。

That by the way, I'm 32 years old.

所以十亿秒前我还没出生呢。

So I wasn't alive a billion seconds ago.

那如果再加三个零，一万亿秒前是什么概念？

Now what about a trillion seconds ago if you just add those three more zeros?

一万亿秒前，纽约曼哈顿还被厚厚的冰层覆盖着。

A trillion seconds ago, Manhattan, New York City was covered under a thick layer of ice.

我再重复一遍。

I'm gonna say that again.

一百万秒前是一周半以前。

A million seconds ago was a week and a half ago.

一百万秒前，这个冷钱包漏洞还没被发现。

A million seconds ago, this cold card vulnerability had not been discovered.

十亿秒前，我还没出生。

A billion seconds ago, I wasn't alive.

一万亿秒前，纽约市还被冰层覆盖着。

A trillion seconds ago, New York City was under ice.

现在你们明白这些数字有多夸张了吗？

Now are you guys understanding just the, like, the ungodly size of these numbers?

我们的大脑其实根本无法真正理解和把握它。

It's it's actually impossible for our brains to, like, truly rack and comprehend.

那我们就来具体看看2的256次方有多大。

So let's spell out the two to the 256.

就是比特币用的那种数字的规模。

Like, the the the numb the size of the numbers that Bitcoin uses.

我在这张幻灯片上把它写出来了。

I wrote it out in this slide.

我甚至都不知道怎么念这个数字。

I don't even know how to pronounce it.

115 夸特罗维吉兰特，792，89。

115 quatrovig vigilante, 792, 89.

这是一个人类大脑根本无法理解的数字。

It's it's a number that the human brain can't even comprehend.

明白吗？

Okay?

通常我不太想放太多，比如

Now I usually don't want to play too much, like

加密货币相关的视频。

video on cryptocurrencies.

我做了两个参考

I made two ref

我通常不太想在播客或视频里放太多长内容，因为大家会觉得无聊。

I I usually don't wanna play too much long form content on a podcast or a video that I do because people get bored.

他们就会关掉。

They exit out.

这个YouTube视频，如果你在播客上听，音频效果也会很好，它非常出色地帮你理解比特币使用的数字到底有多大。

This YouTube video, and the audio is gonna work fine if you're listening on podcasts, is does a phenomenal job at just conceptualizing how large the numbers are that Bitcoin uses.

而且，朋友们，请记住，比特币中真正随机性的关键在于，你需要在结果空间极其庞大的环境中生成数字。

And and again, guys, keep in mind, the whole point of things being truly random in Bitcoin is you need to be creating the number in a space where there's so many outcomes.

也就是说，潜在的数字数量非常多。

Like, there's so many potential numbers.

明白吗？

Okay?

如果它不是真正随机的，那么潜在的结果空间就不够大，这就会给别人机会去猜出你的秘密。

Like, if it's not truly random, then the potential outcomes aren't that big, and that's what gives people an opportunity to guess your secret.

所以，生成一个安全的比特币钱包，核心就在于这个随机性的概念。

So it's all about when you're generating a secure Bitcoin wallet, it's all about this randomness idea.

我是否做到了真正的随机，使得潜在结果空间中的数字数量如此之大，以至于宇宙中没有任何已知的事物拥有足够的时间和能量来遍历所有可能的结果并猜中它。

Am I being truly random so that the amount of numbers in the space of potential outcomes is so big that there's nothing known in the universe that has enough time and enough energy to actually chew through all the potential outcomes and guess it.

这个YouTube视频在让这个概念变得通俗易懂方面做得非常出色。

Now this YouTube video does an unbelievable job at just humanizing this.

大概四分钟。

It's about four minutes.

再说一遍，换作其他情况，我绝不会想放一个四分钟的YouTube视频，但请相信我，耐心一点。

And again, I would never, in another circumstance, want to play a four minute YouTube video, but please trust me on this and just be patient.

它真的能让人直观地理解这些数字的规模和真实大小，然后我们再回过头来，就能明白比特币托管到底是什么，为什么这些数字这么大，以及它为什么这么安全。

It does such a good job at giving human comprehension to the size and true scale of these numbers, which then we will come back to and understand exactly what Bitcoin custody is and why these numbers are so big and how this is so secure.

明白吗？

Okay?

所以，请稍微忍耐一下。

So just bear with me.

我会关掉麦克风，然后播放这个视频。

I'm gonna mute my mic and and play this.

四分钟。

Four minutes.

好，我们搞定了。

You we got it.

搞定了。

We got it.

在关于加密货币的主视频里，我提到了两种情况，要破解某个安全机制，你必须猜对一串256位的特定字符串。

In the main video on cryptocurrencies, I made two references to situations where in order to break a given piece of security, you would have to guess a specific string of 256 bits.

一种情况是在数字签名中，另一种是在加密哈希函数中。

One of these was in the context of digital signatures and the other in the context of a cryptographic hash function.

比如，如果你想找一条消息，它的SHA-256哈希值等于某个特定的256位字符串，那你除了随机猜消息并验证之外，没有更好的办法。

For example, if you wanna find a message whose SHA two fifty six hash is some specific string of 256 bits, you have no better method than to just guess and check random messages.

平均来说，这需要尝试2的256次方次。

And this would require, on average, two to the 256 guesses.

这个数字远远超出了我们日常接触的范围，很难直观感受它有多大，但我们可以试试看。

Now this is a number so far removed from anything that we ever deal with that it can be hard to appreciate its size, but let's give it a try.

2的256次方等于2的32次方自乘8次。

Two to the 256 is the same as two to the 32 multiplied by itself eight times.

这样拆分的好处是，2的32次方是40亿，至少这个数字我们还能想象一下。

Now what's nice about that split is that two to the 32 is 4,000,000,000, which is at least a number we can think about.

对吧？

Right?

就像你在新闻标题里可能会看到的那种数字。

It's the kind of thing you might see in a headline.

所以，我们只需要感受一下，把40亿连续乘以自己八次，到底是个什么概念。

So all we need to do is appreciate what multiplying 4,000,000,000 times itself eight successive times really feels like.

很多人知道，电脑里的GPU可以让你同时进行大量计算，速度非常快。

As many of you know, the GPU on your computer can let you run a whole bunch of computations in parallel incredibly quickly.

如果你专门给GPU编程，让它反复执行加密哈希函数，一台性能很好的GPU每秒大概能处理不到10亿次哈希。

So if you were to specially program a GPU to run a cryptographic hash function over and over, a really good one might be able to do a little less than a billion hashes per second.

假设你往电脑里塞满一堆额外的GPU，让这台电脑每秒能处理40亿次哈希。

And let's say that you just take a bunch of those and cram your computer full of extra GPUs so that your computer can run 4,000,000,000 hashes per second.

那么，这里的第一个40亿就代表每台电脑每秒能处理的哈希次数。

So the first 4,000,000,000 here is gonna represent the number of hashes per second per computer.

现在想象一下，有40亿台这样的装满GPU的电脑。

Now picture 4,000,000,000 of these GPU packed computers.

作为对比，尽管谷歌完全不公开他们的服务器数量，但估计大概在几百万台左右。

For comparison, even though Google does not at all make their number of servers public, estimates have it somewhere in the single digit millions.

实际上，这些服务器中的大多数都比我们想象中那种装满GPU的机器要弱得多。

In reality, most of those servers are gonna be much less powerful than our imagined GPU packed machine.

但假设谷歌把它的几百万台服务器都换成这种机器，那么40亿台机器就相当于大约一千个这种加强版的谷歌。

But let's say that Google replaced all of its millions of servers with a machine like this, then 4,000,000,000 machines would mean about a thousand copies of this souped up Google.

我们就叫它一千谷歌的计算能力吧。

Let's call that one kilo Google worth of computing power.

地球上大约有73亿人。

There's about 7,300,000,000 people on Earth.

所以接下来，想象一下给地球上超过一半的人每人配备一台个人专属的千谷歌。

So next, imagine giving a little over half of every individual on Earth their own personal kilogoogle.

现在再想象一下有40亿个这样的地球。

Now imagine 4,000,000,000 copies of this Earth.

作为对比，银河系大约有一千亿到四千亿颗恒星。

For comparison, the Milky Way has somewhere between one hundred and four hundred billion stars.

我们其实不太确定，但估算值大致在这个范围内。

We don't really know, but the estimates tend to be in that range.

所以这就相当于，银河系中每颗恒星都有1%的概率拥有一颗地球的复制品，而那个地球上有一半的人拥有自己的个人千倍谷歌算力。

So this would be akin to a full 1% of every star in the galaxy having a copy of Earth where half the people on that Earth have their own personal kilogoogle.

接下来，试着想象四十亿个银河系，我们把这叫做你的千兆星系超级计算机，它每秒能进行大约2的160次方次猜测。

Next, try to imagine 4,000,000,000 copies of the Milky Way, and we're gonna call this your gigagalactic supercomputer running about two to the 160 guesses every second.

那么四十亿秒呢？

Now four billion seconds?

那大约是126.8年。

That's about a hundred and twenty six point eight years.

四十亿个这样的时间？

Four billion of those?

嗯，那就是五千零七十亿年，大约是宇宙年龄的37倍。

Well, that's five hundred and seven billion years, which is about 37 times the age of the universe.

所以，就算你有一台每人都配备GPU、装满千谷歌、跨行星、跨星系的超级计算机，连续运算宇宙年龄的37倍时间，它猜对正确数字的概率也只有四十亿分之一。

So even if you were to have your GPU packed kilogoogle per person multiplanetary gigagalactic computer guessing numbers for 37 times the age of the universe, it would still only have a one in 4,000,000,000 chance of finding the correct guess.

顺便说一句，现在比特币挖矿的情况是，所有矿工加在一起每秒猜测的次数……

By the way, the state of Bitcoin hashing these days is that all of the miners put together guessing

各位，这有多厉害？

How valuable was that, guys?

这正好说明了这些数字有多么庞大。

That goes to show the mere size of these numbers.

所以当人们问，杰克，我们真的确定没人能猜出我的密钥吗？

So when people say, well, Jack, are we sure no one can guess my secret?

对。

Yeah.

我确定。

I'm sure.

就像，就像，再说一次，就像刚才那位老兄说的那样。

Like like, again, like that guy just walked through.

你得拥有最强大的计算机，再加上一个千倍于谷歌的计算能力，每个人都有自己的千倍谷歌，还有自己的地球副本，以及银河系中1%的恒星。

You would have to have the most powerful computer and then a gig of amazing Google, like Google times thousands, and each human gets their Google times thousands and then their own copy of Earth and then 1% of the stars in the galaxy.

即便如此，你还需要花费已知宇宙存在时间的37倍。

And then you still would need 37 times the amount of time that the known universe has existed.

而且就算这样，每一次猜测的成功概率也只有四十亿分之一。

And even then, every single guess is a one in 4,000,000,000 chance.

我的意思是，大家想想这个空间有多大，如果你们听我说。

I mean, the the again, guys, the size of the space, if if listen.

如果你真正随机地去做，因为大家知道，如果你只有一比特的熵，那它要么是0要么是1。

If you do it truly randomly, because again, guys, if you have one bit of entropy, then it's either a zero or a one.

那就不安全。

It's not secure.

所以关键在于你的随机性有多随机、多有效。

So it's all about how random, how effective your randomness is.

但如果它是真正随机的，也就是说可能是任何结果之一，那它几乎就是最安全的东西之一，甚至没有之一。

But if it's truly random, meaning it could be any of the potential outcomes, it is like one of the most, if not the most secure things ever.

因为可能的结果空间大得无法想象。

Because the potential space of outcomes is just unfathomably large.

人类的大脑根本没法理解那个数字有多大。

Like, the human brain cannot possibly comprehend the size of that number.

这么说你能明白吗？

Does that make sense?

所以当人们说，那就多掷几次骰子吧。

And so when people say, like, well, just roll a bunch of dice.

在这张幻灯片里，我用了一副扑克牌，因为我经常和迪伦一起打牌。

Well, in this slide, I use a deck of cards because I play cards with Dylan all the time.

我们玩一种叫高尔夫的牌戏。

We play this game called golf.

这不是打扑克，我也不是什么牌类高手。

And it's not like poker, and I'm not like a card player.

对吧？

Right?

这其实就是我们跟未婚妻他们出去玩时玩的一个小游戏，挺有意思的。

It's just like a fun game when we're out with, you know, our fiances and stuff.

有时候有人会手气特别顺，连赢好几把，而我通常负责发牌。

And sometimes someone will go on a run and get really hot and, like, win a bunch of hands in a row, and I'm usually dealing.

大家就会说，哥们，你是不是没洗牌啊，或者说，真不敢相信牌又按同样的顺序出来了。

And people will be like, dude, like, you're not shuffling or, you know, I can't believe that the cards ended up in the same order again.

这挺有意思的，因为作为一个比特币玩家，又懂这些数学知识，我觉得大家可能没意识到，如果你好好洗一副牌，它几乎肯定是宇宙历史上从未有人拿过的顺序。

And it's funny because as a Bitcoiner and someone that's familiar with this math, I don't think people appreciate that if you properly shuffle a deck, it is almost certainly in an order that no one else has ever held in the history of the universe.

这再次说明了这个数学原理是怎么运作的。

And again, this goes to show how this math works.

你明白吗？

You see?

因为，朋友们，如果随机性是真的，而且你好好洗牌，那么潜在的结果——想象一下，就像我们之前说的，一个比特是0或1，两个比特就是00、11、01或10。

Because, again, guys, if you if the randomness is true, and so, like, you shuffle properly, the potential outcomes imagine, you know, how we did well, one bit is zero or one, and two bits is either zero zero, one one, zero one, or one zero.

所以你就从两个结果变成了四个。

So you've gone from two outcomes to four.

现在想象一下，一副扑克牌也是这样。

Now imagine doing that for a deck of cards.

比如，第一次洗牌可能出来的是老K、老K、皇后、皇后。

Like, the first shuffle could be king, king, queen, queen.

对吧？

Right?

所有可能的牌都在里面，还有四种花色、两种颜色，所以每一副洗好的牌，几乎肯定都是历史上没人拿过的顺序。

You've got all the possible cards, and you've got the the four the the two colors, the four suits, and and so every properly shuffled deck is almost certainly in an order that no one else has ever held.

而且要知道，比特币的密钥空间比这还要大14.4亿倍。

And mind you, the key space for Bitcoin is still 1,440,000,000 times larger than that.

所以当有人说掷骰子、洗牌，大家就会觉得，比特币里这些疯狂的人在说什么呢？

So when people say roll a bunch of dice, shuffle a bunch of cards, and people are like, what are these crazy people in Bitcoin talking about?

他们说的掷骰子是什么意思？

What do they mean roll dice?

关键是，他们是在鼓励别人生成足够的随机性。

The point is they're trying people are trying to encourage others to generate sufficient randomness.

足够的随机性。

Sufficient randomness.

就像我们刚才讲的比特，0和1是一个比特。

Because just like we're going through in the bits, zero one is one bit.

00110110是两个比特。

Zero zero one one zero one one zero is two bits.

我怎样才能获得足够的随机性，创造出足够多的可能结果，让猜测的空间变得太大？

How can I get sufficient randomness and create enough potential outcomes where the space to guess is far too large?

有道理。

Makes sense.

我们继续。

Let's go on.

所以关键在于，你的密钥就藏在这个巨大的空间里，这个空间大到宇宙和人类都无法理解其规模。

So the point is your key is somewhere inside of this massive space that, like, the universe and us humans can't even comprehend the size.

关键是，只要它是通过足够随机的方式生成的，就是安全的。

And the point is as long as it's sufficiently generated as random, It's safe.

只要你保管得当，它就很安全。

It's as safe as you can keep it.

所以当有人说存储比特币行不通、自我保管行不通时，我不同意。

So when people say storing Bitcoin is dead, self custody is dead, I disagree.

朋友们，自我保管一直都是一样的。

Self guys, self custody's always been the same.

我不想轻视这次事件，我之后会回到我认为大家应该怎么做、Strike是怎么做的这些话题上。

And I don't wanna make light of this incident, and I'll get all the way back to what I think people should be doing and how Strike does it and all stuff.

但对我来说，一个在比特币领域待了将近十四年的人，自我保管一直都是一样的。

But, like, for someone that's been in Bitcoin for almost fourteen years now, self custody's always been the same.

第一，你是否生成了一个足够大且足够随机的秘密数字？

One, did you generate a large enough and random enough secret number?

是还是不是？

Yes or no?

如果生成了，你如何保护那个数字？

And if you did, how can you protect that number?

而且，在我那个年代，比特币领域只有单签。

And then on top of that, the Bitcoin space back in my day, it was only single sig.

但现在呢，我们有了多签。

And now that nowadays, we have multisig.

还有密钥分片。

We have key sharding.

对。

Okay.

但别让别人吓唬你，或者把保护比特币这件事搞得太复杂。

But don't let people scare you or overcomplicate what securing Bitcoin is.

保护比特币，其实就是生成一个秘密，这个秘密存在于一个足够大的可能性空间里。

Securing Bitcoin is just generating a secret that lives within a space of a large enough amount of potential outcome.

所以它要有足够的随机性。

So it has enough randomness.

要有足够的熵。

It has enough entropy.

然后还要能安全地保管它。

And then being able to keep that safe.

就这么简单。

That's it.

再说一遍，我不是想把它说得太简单。

Again, I don't want to oversimplify it.

我也不想误导大家。

I don't wanna mislead.

这仅供教育用途。

This is for educational purposes only.

但是，你们知道吗，就是这样。

But, you know, you guys, that's it.

原理就是这么回事。

That's how it works.

明白了吗？

Okay?

这就是私钥的样子。

So this is what a private key looks like.

再说一次，这仅供演示用途。

And, again, this is for illustration purposes only.

绝对绝对不要用这个。

Don't ever ever use that.

但这就是它的样子。

But this is what it looks like.

它只是一行字符，这行字符本身没什么特别的。

It's one line, and nothing about the line is particularly special.

但关键在于它完全无法被猜出来。

But everything about it being unguessable is the point.

这就是全部的重点。

That's the whole point.

明白吗？

Okay?

那么现在回到比特币钱包，以及它们的工作原理，还有你们在手机上安装应用时习惯看到的界面，实际上在底层，有人正在创建这个根熵，一个非常非常大、非常非常随机的数字。

So now if we go back to Bitcoin wallets and how they work and what you guys are accustomed to seeing when you download something on your phone, what is actually happening under the hood is someone is creating this root entropy, this really, really large and really, really random number.

明白吗？

Okay?

这个根熵可以被转换并用作种子词。

That is able to be converted to and consumed as seed words.

这些种子词就是你钱包的根。

Those seed words are the root of your wallet.

然后从那里，你可以签名消息，拥有地址，所以你可以从那个地址创建地址，从Stripe向那个地址发送资金。

And then from there, you can sign messages, you can have addresses, so you can create an address from that, send funds from Stripe to that address.

如果你需要从那里转移资金，你可以签名交易并将这些交易发布到比特币网络。

And then if you need to move funds from there, you can sign transactions and publish those transactions to the Bitcoin network.

但这就是比特币钱包，各位。

But that's a Bitcoin wallet, guys.

再次强调，我不是鼓励每个人都自己制作比特币钱包。

Again, I'm not encouraging everyone to make their own Bitcoin wallet.

我不是鼓励大家把所有这些技术都过度简化。

I'm not encouraging everyone to oversimplify all of this technology.

从教育角度来说，别让别人把这事儿搞得太复杂，说什么人类永远无法自己保管比特币。

Educationally, don't let people make this more complicated for you to say like, oh, humans are never gonna be able to self custody Bitcoin.

问题就在于，我们能不能生成一个足够大、足够随机的数字？

It's can we generate a sufficiently large and a sufficiently random number?

能还是不能？

Yes or no?

然后，我们能不能保证它的安全，并围绕它开发出可用的软件？

And then can we keep that secure and build software around that that makes it usable?

就这么简单，各位。

That's it, guys.

就这么回事。

That's it.

这就是Strike在做的事情。

That's what Strike does.

Coinbase 也是这么做的。

That's what Coinbase does.

BitKey 也是这么做的。

That's what BitKey does.

就这么简单。

That's it.

就这么简单。

That's it.

好的。

Okay.

我真的希望你们能明白。

Do you I really hope you guys understand.

我们再回到那个问题：当人们提到比特币的‘秘密’或‘密码’时，这些秘密是不是像我的 Gmail 密码那样，由人类自己选择的？

And let's go back to well, when people use the term in Bitcoin secrets or passwords, you know, are these secrets human chosen, like the thing I'm using for my Gmail account?

不是。

No.

对吧？

Right?

现在你们明白为什么了吧。

And and and now you guys understand why.

因为人类大脑能想出来、能写出来的单词或短语，太容易被猜到了——攻击者会专门挑那些人们常用的内容。

Because words or quotes or just what the human brain can comprehend and produce itself is way too guessable because an attacker searches what people usually pick.

对吧？

Right?

关键就是要找到一个数字空间，大到不可思议，以至于要遍历所有可能的结果，根本不可能。

The whole point is finding a space of numbers that is so unbelievably large, then in order to chew through all the potential outcomes, it's impossible.

根本不可能。

It's impossible.

而且，再说一遍，生活中、安全领域、还有比特币里，没有任何东西是百分之百绝对保证的。

And, again, nothing in life and in security and in Bitcoin is ever, like, super duper guaranteed.

对吧？

Right?

就是说，这完全是概率性的，但实际上是行不通的。

Like, it's it's all probabilistic, but it's infeasible.

对吧？

Right?

这就是为什么用骰子或洗牌来生成随机数。

This is why dice generated entropy are card shuffled entropy.

关键在于如何获得足够的随机性，这本身就很困难。

The point is how do you find sufficient randomness, which in itself is difficult.

对吧？

Right?

不同的钱包有不同的做法，但问题在于，你怎么才能足够随机地生成一个极其巨大、极其随机、几乎不可能被猜到的数字？

Different wallets have different ways of doing it, but it's how can you be sufficiently random to generate this really, really, really large number that's really, really, really, really random that is infeasible to guess?

明白吗？

K?

现在我们来深入聊聊冷钱包，看看今天的情况以及发生了什么。

Now let's start to dig into cold card, what's going on today, and what happened.

所以我想给大家看个东西。

So I wanna show you guys something.

最上面，你看，是一个40位的内部状态。

At the top, okay, is a 40 bit internal state.

这就是冷钱包MK3——那个安全性最低的版本——当时生成的随机性和安全级别。

So this is what the cold card what the the the level of randomness and security that the cold card m k three, the one that was the least secure, that's what it was generating.

而最下面是256位的独立熵值，这才是你真正需要的。

And at the bottom is 256 bits of independent entropy, which is, like, what you want.

明白吗？

Okay?

你会发现它们看起来完全一样。

What you notice is they look the exact same.

这些只是示例数值。

Now these are illustrative values.

这些不是……再说一遍，我只是想说明一个观点。

These these are not this is not the again, I'm I'm just trying to make a point here.

但长度只是告诉你这个数字是怎么写的。

But the length just tells you how the number is written.

对吧？

Okay?

长度只是告诉我们它是256位的。

The length just tells us it's 256 bits.

熵告诉我们攻击者无法排除多少种可能性。

The entropy tells us how many possibilities an attacker cannot rule out.

所以这一切发生的原因，是因为攻击者发现冷钱包只用了40位的内部状态熵，也就是随机性。

So the reason that all of this is happening is because an attacker realized that the cold card was only using a 40 bit internal state level of entropy, of randomness.

这就是为什么会有这些事情。

That's why all of this is happening.

但你看，当人们问，这事儿怎么持续了五年都没人发现？

But do you see how when when people say, how did this go on for five years and no one noticed?

嗯，关键不是我怎么表达这个问题。

Well, the point isn't how do I articulate this?

关键不在于一个安全性较低的密钥看起来有什么不同。

The point isn't that a a a less secure secret looks different.

它们看起来是一样的。

They look the same.

但它们之所以更弱，是因为可能的输出数量要少得多。

But why they're weaker is because the amount of possible outputs is significantly less.

所以，我这里有一个40位的内部状态，只有大约一万亿种可能性，对于普通电脑来说，这个数量并不算多。

So what I have here is this 40 bit internal state that's only around a trillion possibilities, which for a normal computer is not that many.

你可以很快地遍历完一万亿种可能性。

You can chew through a trillion possibilities fairly quickly.

你知道，我们看到冷钱包生成的种子被擦除并转移的案例，有时只需要几分钟，十分钟左右。而如果可能性数量是正确生成的，我们刚才已经讨论过了。

You know, we're seeing instances of cold card generated seeds being wiped and swept in, you know, minutes, in ten minutes versus if the amount of possibilities is generated correctly, we just went over it.

就算你有40个宇宙，每个人类都有几千个古戈尔，每个人类都有一颗拥有银河系1%恒星数量的地球，你仍然远远无法接近那个数量。

Like, there's not enough even if you had 40 universes and thousands of Googles for every human and every human had an Earth with 1% of the stars in the galaxy, you still wouldn't come remotely close.

这就是一百万秒、十亿秒和一万亿秒之间的区别。

That's the difference again from a million seconds versus a billion seconds versus a trillion seconds.

这些指数级的大数字，比你想象的要大得多。

Just these exponentially large numbers are way larger than you think.

对吧？

Okay?

所以，这里还有另一种方式来理解这些东西。

And so here's another way of visualizing this stuff.

如果只有六种可能的输入，那这张幻灯片想表达的是，生成秘密时必须解决随机性的问题。

If there was only ever six possible inputs, the the point of this slide is that the the the randomness has to be solved in generating the secret.

明白吗？

Okay?

而你们从冷钱包里看到的所有东西，比如助记词、这些助记词能生成的地址，以及它们为比特币网络签名的消息，任何人都无法从公开信息中一眼看出问题，然后惊呼‘天哪’。

And all of the things that you guys saw from the cold card, like seed phrases and the addresses that those seed phrases were able to generate and the messages that they were signing for the Bitcoin network, there was no way for anyone to be able to distinctly look at any of the public information and be like, oh my goodness.

冷钱包有问题。

There's something wrong with cold card.

因为所有公开信息——再说一次，它的格式是一样的。

Because all of the public inform again, it the format remains the same.

冷钱包的问题在于随机性不够。

The problem with cold card is there wasn't enough randomness.

也就是说，攻击者需要筛选的可能结果不够多。

Meaning, there wasn't enough possible outcomes that an attacker would have to sift through.

他们可以开始猜测的空间太小了，以至于有些种子，用一台MacBook十分钟就能破解。

The space that they can start guessing was so small that for some of these seeds, it took them ten minutes on a MacBook.

你明白吗？

You see?

所以回到比特币在密码学中的运作方式，以及为什么这如此酷且令人振奋。

So going back to just how Bitcoin works in cryptography and why this is so cool and hopefully inspiring.

想想比特币出现之前的物理世界，如果你对任何东西施加足够的力量，你就能打开任何东西，比如一扇门、一个金库，或者一个国家的边境。

If if you think about the physical world before Bitcoin, if you apply enough force to anything, you can and will open anything, like a door or a gold vault or a country's border.

如果有人带着军队、枪支、警察或FBI出现在你家门口，他们就能闯进来，占领你的房子。

If someone shows up to your front door with the military in a gun or a police force or the FBI, they will get in and take over your house.

你的金库也是一样。

Same thing to your gold vault.

你的国家也一样。

Same thing to your country.

比特币的宝库设计完全不同，因为它基于数学。

Bitcoin's treasure chest is designed very differently because it's math.

强大的密码学扭转了权力平衡。

Strong cryptography inverts the power balance.

这就是它这么酷的原因。

This is why it's so cool.

它颠覆了物理世界的权力格局。

It inverts the power balance of the physical world.

不管有多少人拿着枪闯进我家、我的金库，还是我的国家，都没用。

It doesn't matter how many people show up to my house with a gun or to my gold vault or to my country.

有本事猜我的数字啊。

Good luck guessing my number.

去你的。

Fuck you.

你试着在脑子里想一下，什么东西能那么安全。

Think go through the mental exercise of trying to think of something that's that secure.

因为基本上，如果我带着军队去别人家，那房子就是我的了。

Because pretty much, if I show up to someone's house with the military, it's now my house.

如果我带着军队去别人的国家，那国家就是我的了。

If I show up to someone's country with the military, it's now my country.

如果我带着军队去抢别人的黄金，那黄金就是我的了。

If I show up to someone's gold with the military, it's now my gold.

但如果军队来了，我就说，你们想让我干嘛？

But if the military shows up, I say, well, what do you want me to do, guys?

你们可以杀了我。

You could kill me.

你们可以杀了我的邻居。

You could kill my neighbor.

你们可以占领这片土地，但你们永远猜不到那个数字。

You could take over the land, but you're never going to guess that number ever.

这就是为什么密码学这么酷。

That's why cryptography is so cool.

前提是它得被正确实施和使用。

Only if it's implemented and done properly.

仅此而已。

Only.

各位，这个数字必须足够大，而且足够随机。

Guys, it has to be a large enough and a random enough number.

就这么简单。

That's it.

这是最关键的部分。

That's the most critical part.

这部分绝对不能搞砸。

You cannot fuck that part up.

因为回到那个单比特的例子，如果你只用一比特来加密，那猜起来有多容易？

Because going back to the one bit, if you secure it with one bit, how easy is that to guess?

要么是0，要么是1。

It's either zero or one.

所以冷钱包用40位，40位远远不够。

So when cold card, 40 bits, 40 bits isn't nearly enough.

可能的组合数量远远不够。

Not nearly enough potential outcomes.

攻击者能猜出那个数字，因为可能的组合空间——概率空间根本不够大。

An attacker can guess that number because the potential outcomes is the the the the space of probability just was not big enough.

这就是为什么朱利安·阿桑奇说，再多的武力也解决不了数学问题。

This is why Julian Assange said no amount of course of force will ever solve a math problem.

这就是密码朋克的理念。

This is the cypherpunk idea.

我们终于有了能抵抗武力、武器和暴力的技术。

We finally have technology resistant to force, to weapons, to violence.

你可以杀了我，拿枪指着我的头，但大家想想看。

You can kill me and put a gun to my head, but think about it, guys.

如果你闯进我家，一枪崩了我。

If you walk into my house, you put a bullet in my head.

好吧。

Okay.

你现在占了我的房子。

You got you got my house now.

恭喜你。

Good for you.

好吧。

Okay.

你也拿走了我的金子。

You got my gold too.

好吧。

Okay.

你拿走了我所有的卫衣、冰箱，还有我的健身器材。

You got all my hoodies, and you got my fridge, and and you got my workout equipment.

你猜怎么着？

Guess what?

你猜不到我的数字。

You didn't you can't guess my number.

唯一能保证不泄露我秘密的方法就是杀了我，因为你需要我活着才能解开这个秘密。

You the only way to guarantee you don't get my secret is by killing me because you need me alive to figure out what the secret is.

这就是大数和密码学的力量。

That's the power of large numbers and cryptography.

明白了吗？

You see?

这就是它让人振奋的地方。

That's what's so inspiring about this.

人多力量大。

Strength in numbers.

这就是比特币带来的。

That's what Bitcoin brings.

而且，数学和数字有多容易获取呢？

And by the way, how accessible is math and numbers?

地球上每个人都能用数学，用大数字，还能分享信息。

Everyone on the planet can use math, use large numbers, and share information.

这就是为什么比特币是世界上最容易获取的货币体系，也是最安全的，拥有最纯粹的所有权。

That's why Bitcoin's the most accessible monetary system in the world, and it's the safest with the most distilled property rights.

因为只要你有一个足够大、足够随机的数字，你就安全了。

Because as long as you have a sufficiently large and sufficiently random number, you are secure.

就这么简单。

That's it.

没有军队、没有国家、没有公司，谁也猜不到它。

No military, no state, no corporation, nobody can guess that.

只要你正确生成并妥善保管，就没问题。

As long as you generated it correctly and you kept it safe, you're good.

顺便说一句，各位，这就是自我保管的含义。

That's what self custody is, by the way, guys.

这东西永远不会消亡。

That's never going to die, ever.

如果你把币存在别人那里，你其实就是在说：我相信你生成的数字，相信你用的随机性，也相信你能保护好这些秘密。

And if you are storing your coins with someone else, all you're saying is, I trust you in the number that you generated, in the randomness that you use, and I trust you to secure these secrets.

就这么简单。

That's all you're saying.

你明白吗？

You understand?

那我们现在来聊聊冷钱包的这次故障。

So now let's get into the cold card cold card failure.

因为我在幻灯片上用的说法是，锁本身并没有被破坏。

Because the the terminology I used on the slide here is that the lock itself wasn't broken.

说到底，真正的问题是制钥方没能造出足够好的钥匙。

The keymaker failed at making a good enough key is what honestly happened at the end of the day.

我们来一步步分析一下。

So let's walk through it.

理论上，硬件钱包——既然你们现在理解了比特币的工作原理，其实核心就是安全地生成这个秘密。

A hardware wallet, theoretically, now that you guys understand how Bitcoin works, which it's really just about safely and securely generating this secret.

就这么简单。

That's it.

再说一遍，我不想过度简化，但如果要用大白话跟普通人解释，就是这样。

That again, I don't wanna oversimplify it, but like, so if I were to dumb it down for the layman on the street, that's it.

而一个硬件钱包，如果我把它的功能归结为三点，其实就三个任务。

And a hardware wallet has really three jobs if I were to distill it down to three.

第一，生成。

One, generate.

也就是创建一个足够大、足够随机的根秘密，让任何人都无法预测。

So create a root secret so large and so random that nobody can predict it.

我们刚才已经讲过了，可以利用密码学和那些大到人脑根本无法想象的巨大数字来实现。

And we just went over that, that we can use cryptography and, like, just massive numbers that the human brain can't even comprehend.

明白吗？

Okay?

第二个任务就是保护这个根密钥。

The second job is to protect that root secret.

所以你要把这个根密钥放在不受信任的网络系统之外。

So you keep that root secret away from untrusted network systems.

所以硬件钱包的一个理想状态是，它不会长期连接互联网，也就是不会处于一个广泛的公共网络之中。

So one of the one of the, like, dreams of a hardware wallet is it's not something that can persistently lives on the Internet, which is online and within a broad network, a broad public network.

所以你可以把它放在保险箱里，放在床垫下，或者放在家里的保险柜里。

So it is something that you can put in a safety deposit box that you can put under your mattress, you could put in a vault in your house.

第三个任务就是它必须能够签署和授权交易，因为显然，拥有无法动用的比特币是没有意义的。

And then the third job is it has to be able to sign and authorize transactions because obviously, there's no point in owning Bitcoin that's stuck.

说到底，我们谁也不是为了钱而爱钱。

Eventually, none of us want money for the sake of money itself.

就像你不会为了纸张本身而想要美元，也不会为了比特本身而想要比特币。

Like, you don't want dollars for the sake of the paper or Bitcoins for the sake of the bites.

你想要的是钱能买到的东西。

You want what money can get you.

虽然我们都想囤着不动，但说到底，最终目的还是用它换个大房子。

As much as we wanna huddle and everything, eventually, at some point, the whole point is that it gets you a bigger house.

让孩子的日子过得更好。

It gets your kids a better life.

让老婆拥有梦想中的后院，管它什么鬼样子。

It gets your wife the dream, whatever the fuck, backyard.

所以，如果你不能签名并授权一笔交易，证明你确实拥有与区块链账本记录对应的根密钥。

So if you can't sign and authorize a transaction that you actually own the root secret that corresponds with the ledger entries on the blockchain.

所以，这就是它的三个任务，而冷钱包在第一个任务上就失败了。

So these are technically the three jobs, and cold card failed at the first one.

那么，冷钱包到底搞砸了什么呢？

So what what did cold card fuck up?

既然你们已经大致了解了比特币的运作方式，它就是在生成那个根密钥时出了岔子。

Now that you guys understand from a high level how Bitcoin works, it fucked up at generating that root secret.

它没有生成一个足够随机、没人能预测的数字。

It did not generate a random enough number that nobody can predict.

拥有比特币唯一真正重要的事，它搞砸了。

The one true job of owning Bitcoin, it fucked up.

说实话，我也不想说得这么直接。

Like, I hate to be that blunt.

好吧，我收回那句话。

Honestly, I take that back.

其实我一点也不介意说得这么直接。

I don't hate to be that blunt.

事实就是如此。

That's what happened.

我看到什么就得说什么。

I have to call it how I see it.

比特币钱包的唯一任务，首要任务，就是生成一个足够大、足够随机的数字。

The one job of a Bitcoin wallet, the first job, create a large enough and random enough number.

就这一个要求。

That's it.

结果他们连这个都搞砸了。

And they fucked that up.

那我们来聊聊具体的技术细节，到底发生了什么，因为我看没多少人讨论这件事，至少没看到什么靠谱的分析。

So let's get into some of the technicals of what actually happened because I haven't seen too many people talking about it, at least what I consider to be reasonably accurately.

我再说一遍，这对我来说是个挺有意思的决定，因为我的节目本来就不是那种特别技术流的。

So I'm not again, it's interesting decision on my part because I'm not, like, a highly technical show.

这是给普通人看的，但我觉得你们会感兴趣。

This is for the streets, but I think you guys will be interested in this.

那到底怎么回事呢？我得想想怎么说得简单点。

So what happened is there actually is the how do I dumb this down?

其实冷钱包本来是可以生成足够大、足够随机的根密钥来存储比特币的。

The cold card could have actually generated a large enough and random enough root secret for Bitcoin or storing Bitcoin.

设备本身有这个能力。

It had the capability on the device.

问题是这个功能被关掉了——我不是要散布阴谋论，因为我看了整个事件和相关资料后，觉得这确实是个软件漏洞。

The problem was it was turned off, which I'm not gonna spark conspiracy theories because I actually think that this was a genuine software bug after taking a look at what happened and reading a bit.

但关键是，这简直是个新手才会犯的灾难性错误，这种无能程度真的让人难以理解。

But the point is and a very, like, novice, catastrophic I mean, the level of incompetence here is really difficult.

我真的觉得，Coldcard 在时机成熟时，CoinKite 应该给社区一个事后分析报告，因为我实在搞不懂，听我说。

I really think Coldcard owes when the time is right, CoinKite owes the community a postmortem here because I'm having a tough time comprehending listen.

程序员写代码出 bug 是常有的事。

People write bugs all the time.

安全领域，我们待会会细聊，很大程度上不是要求事事都做到完美无缺。

So much of security guys, which we'll get into in a second, is not doing everything perfectly all the time.

而是设计系统时，要确保即使出了问题，系统依然能扛得住。

It's designing systems that inevitably when shit goes wrong, it's still okay.

这就是安全的核心。

That's security in a nutshell.

对吧？

Okay?

那为什么它会被设成零呢？

So why was why was it set to zero?

我不知道。

I don't know.

但人们总是会写出漏洞。

But people write bugs all the time.

其实这也没什么大不了的。

Like, it's it's okay.

问题在于，冷钱包后来启用了备用方案。

The problem is the cold card then fell back.

想象一下，设备发现：哦，那个经过验证、可靠且随机性足够的熵被关闭了。

Like like, think of the device going, oh oh, the the true tried and true and random enough entropy is turned off.

好吧，那就用B计划，我切换到另一个方案，但这个方案糟糕透了，随机性远远不够，结果不可避免地让很多人损失了大量比特币。

Well, plan b, I'm gonna fall back to this other one, which was awful, not nearly random enough, and inevitably lost a bunch of people a lot of Bitcoin.

但关键在于，冷钱包一开始就有一个备用方案，而这个方案的随机性远远不够。

But it's the mere fact that the cold card had a fallback in the first place that wasn't nearly random enough.

因为就像我之前说的，随机性不够并不意味着它不会生成有效的助记词，也不意味着这些助记词无法在比特币网络上正常使用，因为格式本身并没有改变。

Because like I said before, just because it's not nearly random enough doesn't mean it won't generate, and it won't actually create valid seed words, and those valid seed words won't be able to actually work on the Bitcoin network because, like I said, the format itself doesn't change.