TEDxSydney
Craig Costello: In the war for information, will quantum computers defeat cryptographers?
克雷格·科斯特洛: 密码学家，量子计算机和信息战
Filmed:
Readability: 4.8
1,426,098 views
在窥探我们技术未来的过程中，密码学家克雷格·科斯特洛（Craig Costello）讨论了量子计算机改变世界的潜力。这可能会打破当今机器设定的极限，并为密码破解者提供数字世界的万能钥匙。让我们来了解科斯特洛和他的密码学家同事们如何竞相重塑我们的加密体系来保护互联网。
Craig Costello - Cryptographer
Craig Costello uses mathematics to secure the digital world, both against the threats that exist today and those that may exist in the future. Full bio
Craig Costello uses mathematics to secure the digital world, both against the threats that exist today and those that may exist in the future. Full bio
Double-click the English transcript below to play the video.
我从事保护秘密的工作，
00:12
I'm in the business
of safeguarding secrets,
of safeguarding secrets,
0
782
3275
00:16
and this includes your secrets.
1
4081
2172
其中就包括你们的秘密。
00:19
Cryptographers are
the first line of defense
the first line of defense
2
7206
2134
密码学家是数百年来
00:21
in an ongoing war that's been
raging for centuries:
raging for centuries:
3
9364
3582
持续不断的战争中的
第一道防线：
第一道防线：
00:24
a war between code makers
4
12970
2263
是代码编写者
00:27
and code breakers.
5
15257
1252
和代码破译者之间的战争。
这是一场信息战争。
00:29
And this is a war on information.
6
17030
2094
现代信息战场是数字化的。
00:32
The modern battlefield
for information is digital.
for information is digital.
7
20227
3484
00:35
And it wages across your phones,
8
23735
2162
它发动于你的手机，
00:37
your computers
9
25921
1176
你的电脑
00:39
and the internet.
10
27121
1169
和互联网。
我们的工作是建立系统，
来打乱你们的电子邮件内容，
来打乱你们的电子邮件内容，
00:41
Our job is to create systems that scramble
your emails and credit card numbers,
your emails and credit card numbers,
11
29299
4979
00:46
your phone calls and text messages --
12
34302
2259
信用卡号，电话内容和短信——
00:48
and that includes those saucy selfies --
13
36585
2192
这包括那些搞笑的自拍照——
00:50
(Laughter)
14
38801
1222
（笑声）
00:52
so that all of this information
can only be descrambled
can only be descrambled
15
40047
2753
这样，所有的这些信息
00:54
by the recipient that it's intended for.
16
42824
2121
只能由预期的接收者解密。
一直以来，
00:58
Now, until very recently,
17
46017
2313
我们都一直以为自己
永远赢得了这场战争。
永远赢得了这场战争。
01:00
we thought we'd won this war for good.
18
48354
2555
01:03
Right now, each of your smartphones
is using encryption
is using encryption
19
51694
2945
现在，你们每个人的手机都在使用
01:06
that we thought was unbreakable
and that was going to remain that way.
and that was going to remain that way.
20
54663
3700
我们认为永远
无法被破解的加密手段，
无法被破解的加密手段，
我们错了，
01:11
We were wrong,
21
59654
1940
因为量子计算机即将加入这场战争，
01:13
because quantum computers are coming,
22
61618
2386
01:16
and they're going to change
the game completely.
the game completely.
23
64028
2790
它们会彻底改变游戏规则。
纵观历史，
密码学和密码破解
密码学和密码破解
01:20
Throughout history,
cryptography and code-breaking
cryptography and code-breaking
24
68445
2456
01:22
has always been this game
of cat and mouse.
of cat and mouse.
25
70925
2070
一直是猫和老鼠的游戏。
回到十五世纪，
01:25
Back in the 1500s,
26
73598
1677
苏格兰的玛丽女王认为
她正在发送
她正在发送
01:27
Queen Mary of the Scots thought
she was sending encrypted letters
she was sending encrypted letters
27
75299
3179
只有她的士兵可以破解的加密信件。
01:30
that only her soldiers could decipher.
28
78502
1977
但是英格兰的伊丽莎白女王
01:33
But Queen Elizabeth of England,
29
81074
2046
01:35
she had code breakers
that were all over it.
that were all over it.
30
83144
2400
手下有无数的密码破译者。
01:38
They decrypted Mary's letters,
31
86116
2005
他们破解了玛丽的信件，
发现了她正试图刺杀伊丽莎白，
01:40
saw that she was attempting
to assassinate Elizabeth
to assassinate Elizabeth
32
88145
3173
随后，他们砍掉了玛丽的头。
01:43
and, subsequently,
they chopped Mary's head off.
they chopped Mary's head off.
33
91342
2431
01:47
A few centuries later, in World War II,
34
95729
2352
几个世纪之后的第二次世界大战，
纳粹使用恩尼格玛密码进行通讯，
01:50
the Nazis communicated
using the Engima code,
using the Engima code,
35
98987
2884
01:53
a much more complicated encryption scheme
that they thought was unbreakable.
that they thought was unbreakable.
36
101895
3641
是一种他们认为牢不可破的
更复杂的加密机制。
更复杂的加密机制。
但是之后的艾伦·图灵，
01:58
But then good old Alan Turing,
37
106274
1930
02:00
the same guy who invented
what we now call the modern computer,
what we now call the modern computer,
38
108228
3035
那个发明了我们
称为现代计算机的人，
称为现代计算机的人，
02:03
he built a machine and used it
to break Enigma.
to break Enigma.
39
111287
2615
制作了一个机器，
用它来破解恩尼格玛。
用它来破解恩尼格玛。
他破译了德国人的消息，
02:06
He deciphered the German messages
40
114545
1605
并协助使得希特勒和
他的第三帝国停滞不前。
他的第三帝国停滞不前。
02:08
and helped to bring Hitler
and his Third Reich to a halt.
and his Third Reich to a halt.
41
116174
2715
这种故事已经重复了多个世纪。
02:11
And so the story has gone
throughout the centuries.
throughout the centuries.
42
119772
2559
密码学家不断改善他们的加密方式，
02:14
Cryptographers improve their encryption,
43
122821
2502
然后密码破译者进行反击，
找到一种方法来破解它。
找到一种方法来破解它。
02:17
and then code breakers fight back
and they find a way to break it.
and they find a way to break it.
44
125347
3138
这场战争来来回回，
而且双方差不多并驾齐驱。
而且双方差不多并驾齐驱。
02:20
This war's gone back and forth,
and it's been pretty neck and neck.
and it's been pretty neck and neck.
45
128969
3387
直到 19 世纪 70 年代，
02:25
That was until the 1970s,
46
133533
2715
02:28
when some cryptographers
made a huge breakthrough.
made a huge breakthrough.
47
136272
2660
一些密码学家取得了巨大的突破。
他们发现了一种
非常强大的加密方式，
非常强大的加密方式，
02:31
They discovered an extremely
powerful way to do encryption
powerful way to do encryption
48
139781
3561
02:35
called "public-key cryptography."
49
143366
1752
叫做“公钥密码学”。
与之前用过的所有方式不同，
02:37
Unlike all of the prior methods used
throughout history, it doesn't require
throughout history, it doesn't require
50
145839
4275
它不需要想要交换
秘密信息的通讯双方
秘密信息的通讯双方
02:42
that the two parties that want to send
each other confidential information
each other confidential information
51
150138
3607
02:45
have exchanged the secret key beforehand.
52
153769
2059
提前交换密钥。
公钥密码学的魔力在于，
它允许我们安全地
它允许我们安全地
02:48
The magic of public-key cryptography
is that it allows us to connect securely
is that it allows us to connect securely
53
156602
4112
02:52
with anyone in the world,
54
160738
1544
与世界上任何人连接起来，
无论我们事先交换过数据与否，
02:55
whether we've exchanged
data before or not,
data before or not,
55
163481
2869
02:58
and to do it so fast that you and I
don't even realize it's happening.
don't even realize it's happening.
56
166374
3662
它能让我们可以快速地通讯，
甚至没有意识到它正在发生。
甚至没有意识到它正在发生。
无论你正给同伴发短信相约喝酒，
03:03
Whether you're texting your mate
to catch up for a beer,
to catch up for a beer,
57
171001
3238
03:06
or you're a bank that's transferring
billions of dollars to another bank,
billions of dollars to another bank,
58
174263
4247
还是你正在转账
数十亿美元到另一家银行，
数十亿美元到另一家银行，
03:10
modern encryption enables us
to send data that can be secured
to send data that can be secured
59
178534
3051
现代加密技术使
我们能够在几毫秒内
我们能够在几毫秒内
03:13
in a matter of milliseconds.
60
181609
2021
发送被保护的数据。
03:17
The brilliant idea that makes
this magic possible,
this magic possible,
61
185502
2882
使这个魔法成为可能的绝妙主意，
03:20
it relies on hard mathematical problems.
62
188408
2527
依赖于困难的数学问题。
密码学家对计算器无法
做到的事情深感兴趣。
做到的事情深感兴趣。
03:23
Cryptographers are deeply interested
in things that calculators can't do.
in things that calculators can't do.
63
191623
3834
例如，计算器可以让
你喜欢的任何两个数字相乘，
你喜欢的任何两个数字相乘，
03:29
For example, calculators can multiply
any two numbers you like,
any two numbers you like,
64
197250
3401
03:32
no matter how big the size.
65
200675
1686
无论数字有多大。
但是反过来——
03:35
But going back the other way --
66
203175
1941
03:37
starting with the product and then asking,
67
205140
2218
有相乘后的结果，然后问
03:39
"Which two numbers multiply
to give this one?" --
to give this one?" --
68
207382
2365
“哪两个数字相乘得出的这个数字？”
这实际上是个非常难的问题。
03:41
that's actually a really hard problem.
69
209771
2381
如果我让你找出
哪两个两位数相乘等于 851，
哪两个两位数相乘等于 851，
03:45
If I asked you to find which two-digit
numbers multiply to give 851,
numbers multiply to give 851,
70
213358
4591
即使有计算器，
03:51
even with a calculator,
71
219051
1192
03:52
most people in this room would have
a hard time finding the answer
a hard time finding the answer
72
220267
3107
这个房间里的大多数人
在我完成本次演讲之前，
在我完成本次演讲之前，
都很难找到答案。
03:55
by the time I'm finished with this talk.
73
223398
1916
03:57
And if I make the numbers a little larger,
74
225338
2661
而且如果我让数字变得更大些，
04:00
then there's no calculator on earth
that can do this.
that can do this.
75
228023
3657
地球上没有任何计算器可以做到。
04:03
In fact, even the world's
fastest supercomputer
fastest supercomputer
76
231704
2883
实际上，甚至是世界上
最快的超级电脑
最快的超级电脑
04:06
would take longer
than the life age of the universe
than the life age of the universe
77
234611
2490
要找到两个相乘得到该数字的数字
04:09
to find the two numbers
that multiply to give this one.
that multiply to give this one.
78
237125
2872
将花费比宇宙寿命更长的时间。
而这个问题，被叫做“整数分解”，
04:13
And this problem,
called "integer factorization,"
called "integer factorization,"
79
241029
3341
就是现在你们每部手机和电脑
正在用来保护你们的
正在用来保护你们的
04:16
is exactly what each of your smartphones
and laptops is using right now
and laptops is using right now
80
244394
3626
04:20
to keep your data secure.
81
248044
1534
数据安全的方法。
这是现代加密的基础。
04:22
This is the basis of modern encryption.
82
250254
2417
而地球上所有计算能力联合起来
也无法解决这个问题的事实
也无法解决这个问题的事实
04:26
And the fact that all the computing power
on the planet combined can't solve it,
on the planet combined can't solve it,
83
254266
4210
04:30
that's the reason we cryptographers
thought we'd found a way
thought we'd found a way
84
258500
2873
正是我们密码学家认为
我们找到了一种方式
我们找到了一种方式
能永远领先于编码破坏者的原因。
04:33
to stay ahead of the code
breakers for good.
breakers for good.
85
261397
2258
也许我们有点自大，
04:37
Perhaps we got a little cocky
86
265131
1652
因为就在我们以为战争胜利的时候，
04:39
because just when we thought
the war was won,
the war was won,
87
267902
2346
04:42
a bunch of 20th-century physicists
came to the party,
came to the party,
88
270272
2938
一批 20 世纪的物理学家
也加入了进来，
也加入了进来，
04:45
and they revealed
that the laws of the universe,
that the laws of the universe,
89
273234
2679
他们揭示了宇宙的定律
04:47
the same laws that modern
cryptography was built upon,
cryptography was built upon,
90
275937
2595
并不是我们想象的那样，
而现代密码学的建立
就基于这些定律。
就基于这些定律。
04:51
they aren't as we thought they were.
91
279422
1815
我们认为一个物体
不能同时处于两个地方。
不能同时处于两个地方。
04:54
We thought that one object couldn't be
in two places at the same time.
in two places at the same time.
92
282205
3511
事实并非如此。
04:58
It's not the case.
93
286262
1541
我们认为没有任何东西可以
04:59
We thought nothing can possibly spin
clockwise and anticlockwise
clockwise and anticlockwise
94
287827
3712
同时进行顺时针和逆时针旋转。
05:03
simultaneously.
95
291563
1285
但这也不是正确的。
05:05
But that's incorrect.
96
293265
1387
我们认为分别位于
宇宙两侧的两个物体
宇宙两侧的两个物体
05:07
And we thought that two objects
on opposite sides of the universe,
on opposite sides of the universe,
97
295173
3710
05:10
light years away from each other,
98
298907
2301
彼此相距若干光年，
05:13
they can't possibly influence
one another instantaneously.
one another instantaneously.
99
301232
3566
它们不可能瞬间相互影响。
我们又错了。
05:17
We were wrong again.
100
305932
1247
生活也总是这样，不是吗？
05:20
And isn't that always the way
life seems to go?
life seems to go?
101
308403
2209
就在你认为你搞定了所有事情，
万事俱备的时候，
万事俱备的时候，
05:22
Just when you think you've got
everything covered, your ducks in a row,
everything covered, your ducks in a row,
102
310636
3396
一批物理学家出现，
05:26
a bunch of physicists come along
103
314056
1555
并揭示了宇宙的基本定律
05:27
and reveal that the fundamental laws
of the universe are completely different
of the universe are completely different
104
315635
3692
与你想的完全不同？
（笑声）
它搞砸了一切。
05:31
to what you thought?
105
319351
1161
05:32
(Laughter)
106
320536
1058
05:33
And it screws everything up.
107
321618
1356
结果就是，在微小的亚原子领域，
05:34
See, in the teeny tiny subatomic realm,
108
322998
4526
05:39
at the level of electrons and protons,
109
327548
3012
在电子和质子的级别上，
05:42
the classical laws of physics,
110
330584
1822
我们都熟知和热爱的
05:44
the ones that we all know and love,
111
332430
1840
物理的经典定律，
05:46
they go out the window.
112
334294
1238
不复存在。
05:48
And it's here that the laws
of quantum mechanics kick in.
of quantum mechanics kick in.
113
336023
2811
而量子力学定律就在这里展开。
在量子力学中，
05:51
In quantum mechanics,
114
339688
1186
05:52
an electron can be spinning clockwise
and anticlockwise at the same time,
and anticlockwise at the same time,
115
340898
4478
电子可以同时进行
顺时针和逆时针旋转，
顺时针和逆时针旋转，
05:57
and a proton can be in two places at once.
116
345400
2564
而一个质子可以
同时处于两个位置。
同时处于两个位置。
这听起来像科幻小说，
06:01
It sounds like science fiction,
117
349940
2123
06:04
but that's only because
the crazy quantum nature of our universe,
the crazy quantum nature of our universe,
118
352087
4195
但是这仅仅是因为
宇宙的疯狂量子本质，
宇宙的疯狂量子本质，
06:08
it hides itself from us.
119
356306
1671
对我们隐藏了自己，
直到 20 世纪。
06:10
And it stayed hidden from us
until the 20th century.
until the 20th century.
120
358884
3292
但是现在我们看见了，
整个世界
整个世界
06:15
But now that we've seen it,
the whole world is in an arms race
the whole world is in an arms race
121
363494
3769
都在争相尝试建造量子计算机——
06:19
to try to build a quantum computer --
122
367287
2276
一种能够利用古怪的
量子行为力量的计算机。
量子行为力量的计算机。
06:22
a computer that can harness the power
of this weird and wacky quantum behavior.
of this weird and wacky quantum behavior.
123
370455
4339
这些东西太具有颠覆性了，
06:28
These things are so revolutionary
124
376375
2456
06:30
and so powerful
125
378855
1766
而且如此强大，
06:32
that they'll make today's
fastest supercomputer
fastest supercomputer
126
380645
2353
会使得现在最快的超级计算机
06:35
look useless in comparison.
127
383022
2080
相比之下看起来毫无用处。
实际上，对于我们非常
感兴趣的某些问题，
感兴趣的某些问题，
06:37
In fact, for certain problems
that are of great interest to us,
that are of great interest to us,
128
385868
3018
如今最快的超级电脑
更接近于一个算盘，
更接近于一个算盘，
06:41
today's fastest supercomputer
is closer to an abacus
is closer to an abacus
129
389633
2611
而不是量子计算机。
06:44
than to a quantum computer.
130
392268
1675
是的，我说的就是那种
带有珠子的小小的木制品。
带有珠子的小小的木制品。
06:45
That's right, I'm talking about
those little wooden things with the beads.
those little wooden things with the beads.
131
393967
3536
量子计算机可以
模拟化学和生物过程，
模拟化学和生物过程，
06:50
Quantum computers can simulate
chemical and biological processes
chemical and biological processes
132
398477
4268
这远远超出了传统计算机的范围。
06:54
that are far beyond the reach
of our classical computers.
of our classical computers.
133
402769
2906
因此，它们很可能会帮助我们
解决地球上一些最大的问题。
解决地球上一些最大的问题。
06:58
And as such, they promise to help us solve
some of our planet's biggest problems.
some of our planet's biggest problems.
134
406812
5591
他们将帮助我们战胜全球饥饿；
07:05
They're going to help us
combat global hunger;
combat global hunger;
135
413492
2272
应对气候变化，
07:09
to tackle climate change;
136
417074
2317
找到我们迄今为止未能成功的
治疗疾病和全球性传染病的方法，
治疗疾病和全球性传染病的方法，
07:11
to find cures for diseases and pandemics
for which we've so far been unsuccessful;
for which we've so far been unsuccessful;
137
419415
3960
创造超人类的人工智能，
07:16
to create superhuman
artificial intelligence;
artificial intelligence;
138
424213
2909
以及比所有这些事情都重要的，
07:20
and perhaps even more important
than all of those things,
than all of those things,
139
428034
2904
它将帮助我们理解宇宙的本质。
07:22
they're going to help us understand
the very nature of our universe.
the very nature of our universe.
140
430962
3726
但是伴随着不可思议的潜力，
07:28
But with this incredible potential
141
436376
2214
也带来了不可思议的风险。
07:31
comes an incredible risk.
142
439788
1631
还记得我之前说过的大数字吗？
07:34
Remember those big numbers
I talked about earlier?
I talked about earlier?
143
442785
2384
我现在说的不是 851。
07:38
I'm not talking about 851.
144
446152
2099
实际上，如果你们任何人
07:40
In fact, if anyone in here
has been distracted
has been distracted
145
448275
2181
因为要找到这些因数而分心，
07:42
trying to find those factors,
146
450480
1439
我要把你从苦难中解救出来，
告诉你答案是 23 乘 37 。
告诉你答案是 23 乘 37 。
07:43
I'm going to put you out of your misery
and tell you that it's 23 times 37.
and tell you that it's 23 times 37.
147
451943
3554
（笑声）
07:47
(Laughter)
148
455521
1194
我要说的是比那大得多的数字。
07:48
I'm talking about the much
bigger number that followed it.
bigger number that followed it.
149
456739
2735
虽然当今最快的超级计算机
无法在宇宙生命周期中
无法在宇宙生命周期中
07:52
While today's fastest supercomputer
couldn't find those factors
couldn't find those factors
150
460300
3500
07:55
in the life age of the universe,
151
463824
2333
找到那些因数，
07:58
a quantum computer
could easily factorize numbers
could easily factorize numbers
152
466181
2880
但一个量子计算机可以轻易的
08:01
way, way bigger than that one.
153
469085
1567
分解比那大很多很多的数字。
量子计算机将打破我们现在
用来保护大家免受
用来保护大家免受
08:03
Quantum computers will break
all of the encryption currently used
all of the encryption currently used
154
471882
3410
08:07
to protect you and I from hackers.
155
475316
1978
黑客攻击的所有加密算法。
08:09
And they'll do it easily.
156
477318
1427
它们会轻松做到的。
让我这样说吧：
08:12
Let me put it this way:
157
480539
1333
如果量子计算是一根长矛，
08:13
if quantum computing was a spear,
158
481896
1770
那么现代加密——
08:16
then modern encryption,
159
484666
1535
几十年来一直保护着我们的
牢不可破的系统，
牢不可破的系统，
08:18
the same unbreakable system
that's protected us for decades,
that's protected us for decades,
160
486225
3373
就像是纸巾做的盾牌。
08:21
it would be like a shield
made of tissue paper.
made of tissue paper.
161
489622
2658
有权访问量子计算机的任何人
都将拥有万能钥匙，
都将拥有万能钥匙，
08:25
Anyone with access to a quantum computer
will have the master key
will have the master key
162
493578
3988
08:29
to unlock anything they like
in our digital world.
in our digital world.
163
497590
2688
可以解锁他们在数字化世界中
喜欢的任何东西。
喜欢的任何东西。
他们可以从银行偷钱，
08:33
They could steal money from banks
164
501293
1812
并控制经济，
08:35
and control economies.
165
503129
1431
他们可以关闭医院电源，
或者发射核武器，
或者发射核武器，
08:37
They could power off hospitals
or launch nukes.
or launch nukes.
166
505303
2897
或者他们可以只是坐下来，
通过网络摄像头看着我们，
通过网络摄像头看着我们，
08:40
Or they could just sit back
and watch all of us on our webcams
and watch all of us on our webcams
167
508224
3337
08:43
without any of us knowing
that this is happening.
that this is happening.
168
511585
2358
而我们没有人知道发生了什么。
我们习惯使用的
所有计算机上的基本信息单元，
所有计算机上的基本信息单元，
08:49
Now, the fundamental unit of information
on all of the computers we're used to,
on all of the computers we're used to,
169
517314
3959
08:53
like this one,
170
521297
1505
像这个，
叫做一个“比特”。
08:54
it's called a "bit."
171
522826
1342
一个比特可以处于两个状态之一：
08:56
A single bit can be one of two states:
172
524651
2223
08:58
it can be a zero or it can be a one.
173
526898
2259
它可以是 0 或者 1。
当我和地球另一端的妈妈
视频的时候——
视频的时候——
09:02
When I FaceTime my mum
from the other side of the world --
from the other side of the world --
174
530157
2828
她会因为我做了
这张幻灯片杀了我的——
这张幻灯片杀了我的——
09:05
and she's going to kill
me for having this slide --
me for having this slide --
175
533746
2486
09:08
(Laughter)
176
536256
1395
（笑声）
我们实际上只是在给彼此
发送一长串的 0 和 1，
发送一长串的 0 和 1，
09:09
we're actually just sending each other
long sequences of zeroes and ones
long sequences of zeroes and ones
177
537675
3734
09:13
that bounce from computer to computer,
from satellite to satellite,
from satellite to satellite,
178
541433
3202
在计算机之间，卫星之间反复，
高速地传输着我们的数据。
09:16
transmitting our data at a rapid pace.
179
544659
2146
比特当然非常有用。
09:18
Bits are certainly very useful.
180
546829
2003
09:20
In fact, anything
we currently do with technology
we currently do with technology
181
548856
2696
实际上，我们现在
技术上做的任何事情
技术上做的任何事情
09:23
is indebted to the usefulness of bits.
182
551576
2062
都多亏了比特。
但是我们开始意识到，
09:26
But we're starting to realize
183
554840
1389
09:28
that bits are really poor at simulating
complex molecules and particles.
complex molecules and particles.
184
556253
4515
在模拟复杂的分子和粒子方面，
比特做得很差。
比特做得很差。
这是因为，在某种意义上，
09:33
And this is because, in some sense,
185
561394
1976
09:35
subatomic processes can be doing
two or more opposing things
two or more opposing things
186
563394
3085
亚原子过程可以同时做两个或更多
相反的事情，
09:38
at the same time
187
566503
1188
09:39
as they follow these bizarre rules
of quantum mechanics.
of quantum mechanics.
188
567715
2986
因为他们遵循量子力学的
这些怪异规则。
这些怪异规则。
所以，上个世纪后期，
09:43
So, late last century,
189
571232
1544
一些非常聪明的物理学家
09:44
some really brainy physicists
had this ingenious idea:
had this ingenious idea:
190
572800
3217
有了这个巧妙的想法：
09:48
to instead build computers
that are founded
that are founded
191
576041
2001
建立基于量子力学原理的计算机。
09:50
on the principles of quantum mechanics.
192
578066
2090
量子计算机的基本信息单位
09:54
Now, the fundamental unit of information
of a quantum computer,
of a quantum computer,
193
582557
3219
叫做一个“量子比特” （qubit），
09:57
it's called a "qubit."
194
585800
1248
是 “quantum bit”的缩写。
09:59
It stands for "quantum bit."
195
587582
1800
一个量子比特可以有无限个状态，
10:02
Instead of having just two states,
like zero or one,
like zero or one,
196
590986
3257
而不再是只有 0 或 1 两个状态。
10:06
a qubit can be an infinite
number of states.
number of states.
197
594267
2889
这对应于它同时是 0 和 1 的
10:09
And this corresponds to it being
some combination of both zero and one
some combination of both zero and one
198
597849
3666
10:13
at the same time,
199
601539
1787
某种组合，
10:15
a phenomenon that we call "superposition."
200
603350
2189
我们称这种现象为“叠加”。
当我们有两个量子比特
叠加在一起时，
叠加在一起时，
10:18
And when we have two qubits
in superposition,
in superposition,
201
606569
2705
10:21
we're actually working across
all four combinations
all four combinations
202
609298
2382
实际上，我们正在研究四种组合，
0 - 0 ，0 - 1 ，1 - 0 ，和 1 - 1。
10:23
of zero-zero, zero-one,
one-zero and one-one.
one-zero and one-one.
203
611704
2510
有三个量子比特时，
10:26
With three qubits,
204
614940
1346
10:28
we're working in superposition
across eight combinations,
across eight combinations,
205
616310
3241
我们在研究八种组合的叠加状态，
10:31
and so on.
206
619575
1152
以此类推。
每次我们增加一个量子比特，
我们需要同时处理的
我们需要同时处理的
10:33
Each time we add a single qubit,
we double the number of combinations
we double the number of combinations
207
621294
3950
叠加状态的组合数量
10:37
that we can work with in superposition
208
625268
3602
将加倍。
10:40
at the same time.
209
628894
1179
所以当我们扩大规模，
处理很多量子比特时，
处理很多量子比特时，
10:43
And so when we scale up
to work with many qubits,
to work with many qubits,
210
631005
2629
10:45
we can work with an exponential
number of combinations
number of combinations
211
633658
3622
我们需要同时处理的
组合状态数量呈指数型增加。
10:49
at the same time.
212
637304
1319
而这就暗示了量子计算的
力量从何而来。
力量从何而来。
10:51
And this just hints at where the power
of quantum computing is coming from.
of quantum computing is coming from.
213
639440
3635
如今，在现代加密中，
10:56
Now, in modern encryption,
214
644964
1327
我们的密钥，
例如大数的分解因子，
例如大数的分解因子，
10:59
our secret keys, like the two factors
of that larger number,
of that larger number,
215
647429
3928
11:03
they're just long sequences
of zeroes and ones.
of zeroes and ones.
216
651381
2277
它们只是 0 和 1 的长序列。
为了找到它们，
11:06
To find them,
217
654539
1244
11:07
a classical computer must go through
every single combination,
every single combination,
218
655807
4444
一个传统计算机必须
实验所有的组合可能，
实验所有的组合可能，
11:12
one after the other,
219
660275
1151
一个接着一个，
11:13
until it finds the one that works
and breaks our encryption.
and breaks our encryption.
220
661450
3079
直到找到那对可以
成功破译加密的组合。
成功破译加密的组合。
但是在量子计算机中，
11:18
But on a quantum computer,
221
666191
1548
有了足够多的
叠加状态的量子比特，
叠加状态的量子比特，
11:20
with enough qubits in superposition,
222
668779
3193
可以在同一时间
从所有组合中提取信息。
从所有组合中提取信息。
11:25
information can be extracted
from all combinations at the same time.
from all combinations at the same time.
223
673001
4331
11:30
In very few steps,
224
678912
1254
只需几个步骤，
11:32
a quantum computer can brush aside
all of the incorrect combinations,
all of the incorrect combinations,
225
680190
3974
一个量子计算机就可以
撇开所有不正确的组合，
撇开所有不正确的组合，
留住正确的那个，
11:36
home in on the correct one
226
684188
1413
11:37
and then unlock our treasured secrets.
227
685625
2061
然后解锁我们珍贵的秘密。
在疯狂的量子级别，
11:44
Now, at the crazy quantum level,
228
692215
2566
着实令人难以置信的事情发生了。
11:47
something truly incredible
is happening here.
is happening here.
229
695900
2622
许多顶尖物理学家所拥有的
传统智慧——
传统智慧——
11:52
The conventional wisdom
held by many leading physicists --
held by many leading physicists --
230
700625
3674
这点你们得跟上我——
11:56
and you've got to stay
with me on this one --
with me on this one --
231
704323
2619
11:58
is that each combination is actually
examined by its very own quantum computer
examined by its very own quantum computer
232
706966
4423
每个组合实际上
是由自己的量子计算机
是由自己的量子计算机
在自己的平行宇宙中检验的。
12:03
inside its very own parallel universe.
233
711413
2549
每个组合，它们像波浪一样
积聚在水池中。
积聚在水池中。
12:07
Each of these combinations,
they add up like waves in a pool of water.
they add up like waves in a pool of water.
234
715303
3901
错误的那些组合，
12:12
The combinations that are wrong,
235
720085
1986
12:14
they cancel each other out.
236
722095
1978
它们相互抵消掉。
12:16
And the combinations that are right,
237
724097
1760
而那些正确的组合，
12:17
they reinforce and amplify each other.
238
725881
1859
它们加强并相互扩大。
所以在量子计算过程结束时，
12:20
So at the end of the quantum
computing program,
computing program,
239
728241
2665
12:22
all that's left is the correct answer,
240
730930
2817
留下了的就只是
我们可以在这个宇宙中
我们可以在这个宇宙中
12:25
that we can then observe
here in this universe.
here in this universe.
241
733771
2553
看到的正确的答案。
如果你没有完全搞懂，
不要紧张。
不要紧张。
12:29
Now, if that doesn't make
complete sense to you, don't stress.
complete sense to you, don't stress.
242
737575
3136
12:32
(Laughter)
243
740735
1048
（笑声）
12:33
You're in good company.
244
741807
1223
有人陪你们。
尼尔斯·波尔，
这个领域的先驱者之一，
这个领域的先驱者之一，
12:36
Niels Bohr, one of
the pioneers of this field,
the pioneers of this field,
245
744205
3166
他曾经说过任何
认真去思考量子力学
认真去思考量子力学
12:39
he once said that anyone
who could contemplate quantum mechanics
who could contemplate quantum mechanics
246
747395
3007
而没有被深深震惊到的人，
12:42
without being profoundly shocked,
247
750426
2363
12:44
they haven't understood it.
248
752813
1456
只是还没有理解它。
12:46
(Laughter)
249
754293
1427
（笑声）
但是你们已经知道了
我们要面对的，
我们要面对的，
12:47
But you get an idea
of what we're up against,
of what we're up against,
250
755744
2155
以及为什么现在我们的密码学家
12:49
and why it's now up to us cryptographers
251
757923
2062
12:52
to really step it up.
252
760009
1363
要加紧准备应对它。
12:54
And we have to do it fast,
253
762674
2089
而且我们必须行动迅速，
12:56
because quantum computers,
254
764787
2032
因为量子计算机
已经存在于世界各地的实验室中。
12:58
they already exist in labs
all over the world.
all over the world.
255
766843
3023
幸运的是，目前，
13:03
Fortunately, at this minute,
256
771248
1897
13:05
they only exist
at a relatively small scale,
at a relatively small scale,
257
773169
2670
它们仅以相对较小的规模存在，
13:07
still too small to break
our much larger cryptographic keys.
our much larger cryptographic keys.
258
775863
3065
规模尚无法攻破我们那些
数量庞大的加密密钥。
数量庞大的加密密钥。
13:12
But we might not be safe for long.
259
780127
1684
但是我们安全不了太久了。
有些人认为秘密政府机构
13:14
Some folks believe that secret
government agencies
government agencies
260
782968
2496
13:17
have already built a big enough one,
261
785488
1913
已经建立了一个
足够大的量子计算机，
足够大的量子计算机，
13:19
and they just haven't told anyone yet.
262
787425
1973
只是他们还没有告诉任何人。
一些专家说，还有十年时间。
13:21
Some pundits say
they're more like 10 years off.
they're more like 10 years off.
263
789961
2429
13:24
Some people say it's more like 30.
264
792414
1860
一些人说更有可能是 30 年。
你们可能认为如果我们
距离量子计算机还有十年之远，
距离量子计算机还有十年之远，
13:27
You might think that
if quantum computers are 10 years away,
if quantum computers are 10 years away,
265
795163
2857
我们密码学家肯定还有
足够的时间可以想出办法
足够的时间可以想出办法
13:30
surely that's enough time
for us cryptographers to figure it out
for us cryptographers to figure it out
266
798044
3064
来及时保护我们的网络。
13:33
and to secure the internet in time.
267
801132
1694
但是不幸的是，没有那么容易。
13:34
But unfortunately, it's not that easy.
268
802850
1887
即使我们忽略进行标准化和部署
13:37
Even if we ignore
the many years that it takes
the many years that it takes
269
805521
2188
所要花费的多年时间，
然后推出新的加密技术，
然后推出新的加密技术，
13:39
to standardize and deploy and then
roll out new encryption technology,
roll out new encryption technology,
270
807733
3666
13:43
in some ways we may already be too late.
271
811423
2328
在某些方面，
我们可能已经来不及了。
我们可能已经来不及了。
精明的数字犯罪分子和政府机构
13:47
Smart digital criminals
and government agencies
and government agencies
272
815407
3172
13:50
may already be storing
our most sensitive encrypted data
our most sensitive encrypted data
273
818603
4279
可能已经抢在量子计算机
大规模应用之前，
大规模应用之前，
开始存储我们最敏感的机密数据了。
13:54
in anticipation for
the quantum future ahead.
the quantum future ahead.
274
822906
2593
外国领导人，
13:59
The messages of foreign leaders,
275
827069
1738
战争将军，
14:02
of war generals
276
830100
1355
或者质疑权力的个人，
14:04
or of individuals who question power,
277
832653
2162
他们的信息现在是加密的。
14:07
they're encrypted for now.
278
835936
1550
但是只要那一天到来，
14:10
But as soon as the day comes
279
838487
1601
14:12
that someone gets their hands
on a quantum computer,
on a quantum computer,
280
840112
2776
有人有能力操作量子计算机，
14:14
they can retroactively break
anything from the past.
anything from the past.
281
842912
3126
他们就可以追溯性地
破解过去的一切信息。
破解过去的一切信息。
在某些政府和金融部门，
14:19
In certain government
and financial sectors
and financial sectors
282
847078
2030
14:21
or in military organizations,
283
849132
1403
或在军事机构中，
14:22
sensitive data has got to remain
classified for 25 years.
classified for 25 years.
284
850559
3074
敏感数据必须保密 25 年。
14:26
So if a quantum computer
really will exist in 10 years,
really will exist in 10 years,
285
854273
3180
所以如果量子计算机
真的在十年后出现，
真的在十年后出现，
那么这些人晚了 15 年，
14:29
then these guys are already
15 years too late
15 years too late
286
857477
2290
14:31
to quantum-proof their encryption.
287
859791
1710
已经来不及应对量子危机。
所以当世界各地的科学家
14:34
So while many scientists around the world
288
862858
1976
竞相尝试建造量子计算机时，
14:36
are racing to try to build
a quantum computer,
a quantum computer,
289
864858
2903
我们密码学家正迫切
重塑我们的加密系统，
重塑我们的加密系统，
14:39
us cryptographers are urgently
looking to reinvent encryption
looking to reinvent encryption
290
867785
3450
14:43
to protect us long before that day comes.
291
871259
2202
以在那天到来之前保护我们。
我们正在寻找新的数学难题。
14:46
We're looking for new,
hard mathematical problems.
hard mathematical problems.
292
874718
2974
我们正在找
像数字分解那样的难题，
像数字分解那样的难题，
14:50
We're looking for problems that,
just like factorization,
just like factorization,
293
878435
3011
14:53
can be used on our smartphones
and on our laptops today.
and on our laptops today.
294
881470
3009
可以用在我们如今的
智能手机和电脑上。
智能手机和电脑上。
但是不同于数字分解，
我们需要这个难题足够难，
我们需要这个难题足够难，
14:57
But unlike factorization,
we need these problems to be so hard
we need these problems to be so hard
295
885596
4375
15:01
that they're even unbreakable
with a quantum computer.
with a quantum computer.
296
889995
2846
难到它不能被量子计算机破解。
最近几年，我们一直在
探索更广阔的数学领域，
探索更广阔的数学领域，
15:06
In recent years, we've been digging around
a much wider realm of mathematics
a much wider realm of mathematics
297
894366
3606
15:09
to look for such problems.
298
897996
1526
来寻找这样的难题。
我们一直在看那些
15:12
We've been looking at numbers and objects
299
900205
1971
比你我习惯所见更加奇特的，
15:14
that are far more exotic
and far more abstract
and far more abstract
300
902200
2168
比计算器上的那些抽象得多的
15:16
than the ones that you and I are used to,
301
904392
1956
数字和对象。
15:18
like the ones on our calculators.
302
906372
1597
而且我们相信我们
已经找到了一些几何问题，
已经找到了一些几何问题，
15:19
And we believe we've found
some geometric problems
some geometric problems
303
907993
2380
可能会有帮助。
15:22
that just might do the trick.
304
910397
1399
它不像那些我们
在高中时用图纸和笔
在高中时用图纸和笔
15:24
Now, unlike those two-
and three-dimensional geometric problems
and three-dimensional geometric problems
305
912383
3063
解决的二维或三维几何问题，
15:27
that we used to have to try to solve
with pen and graph paper in high school,
with pen and graph paper in high school,
306
915470
3699
它们大多数定义在 500 个维度以上。
15:31
most of these problems are defined
in well over 500 dimensions.
in well over 500 dimensions.
307
919193
4229
所以它们不只在草纸上
难以描述和解决，
难以描述和解决，
15:36
So not only are they a little hard
to depict and solve on graph paper,
to depict and solve on graph paper,
308
924453
3756
而且我们相信它们超出了
量子计算机的计算范围。
量子计算机的计算范围。
15:40
but we believe they're even
out of the reach of a quantum computer.
out of the reach of a quantum computer.
309
928233
3472
所以虽然现在还早，
15:45
So though it's early days,
310
933392
1697
15:47
it's here that we are putting our hope
as we try to secure our digital world
as we try to secure our digital world
311
935113
4505
但此时此刻，我们希望
在步入量子未来时，
在步入量子未来时，
15:51
moving into its quantum future.
312
939642
1970
可以确保我们数字世界的安全。
就像所有其他的科学家，
15:55
Just like all of the other scientists,
313
943171
1853
15:57
we cryptographers are tremendously excited
314
945048
2163
我们密码学家对于未来
与量子计算机
与量子计算机
15:59
at the potential of living in a world
alongside quantum computers.
alongside quantum computers.
315
947235
3857
一起生活的世界感到非常兴奋。
这可能是正义的力量。
16:04
They could be such a force for good.
316
952839
2153
但是无论未来
我们有什么样的技术，
我们有什么样的技术，
16:09
But no matter what
technological future we live in,
technological future we live in,
317
957508
4248
我们的秘密都将一直是
我们人性的一部分，
我们人性的一部分，
16:16
our secrets will always be
a part of our humanity.
a part of our humanity.
318
964867
4856
16:22
And that is worth protecting.
319
970637
2234
而它们值得被保护。
谢谢。
16:25
Thanks.
320
973559
1154
16:26
(Applause)
321
974737
3106
（掌声）
ABOUT THE SPEAKER
Craig Costello - CryptographerCraig Costello uses mathematics to secure the digital world, both against the threats that exist today and those that may exist in the future.
Why you should listen
Together with his colleagues, Craig Costello builds software with the goal of safeguarding the internet before large-scale quantum computing becomes a reality. He is a senior researcher in the Cryptography and Security Group at Microsoft Research in the USA. He is primarily interested in the cryptographic applications of computational number theory, in particular curve-, pairing- and lattice-based cryptography.
More profile about the speakerCraig Costello | Speaker | TED.com