Jesse Pollak's talk on Cryptography 101 and WordCamp Minneapolis

1. hi y’all, i’m jesse

2. hi y’all, i’m jesse
co-founder at clef

3. hi y’all, i’m jesse
@jessepollak
co-founder at clef

4. cryptography

5. cRyPtOgRaPhY

6. cryptography

7. goals

8. goals
give you a basic knowledge of
what crypto is and how it works.

9. goals
give you a basic knowledge of
what crypto is and how it
use examples you can understand

10. goals
give you a basic knowledge of
what crypto is and how it
use examples you can understand
help you realize that crypto isn’t
scary.

11. goals
give you a basic knowledge of
what crypto is and how it works.
use examples you can understand
help you realize that crypto isn’t
scary.

12. again, i’m jesse
@jessepollak
co-founder at clef

13. crypto 101

14. crypto 101
getclef.com/crypto101

15. cryptography
the art of writing or solving codes

16. cryptography
the art of writing or solving codes
the practice and study of techniques
to communicate securely in the
presence of third-parties.

17. cryptography
the art of writing or solving codes
the practice and study of techniques
to communicate securely in the
presence of third-parties.
how we use the web without hackers
stealing our identities and information

18. so, what?

19. so, what?
where is cryptography actually used?

20. 1 passwords

21. 1 passwords
2 clef

22. 1 passwords
2 clef
3 SSL

23. 1 passwords
2 clef
3 SSL

24. what is SSL?

25. what is TLS?

26. what is HTTPS?

27. ssl
the way we browse the web without
anyone else listening in.

28. core problem

29. how can two people communicate
securely?
alicebob

30. two subproblems

31. “your message”
1

32. “fd64$%533#$$1”
“your message”
1

33. “your message”
“fd64$%533#$$1”
“your message”
1

34. encryption
1
alicebob

35. 2
bob

36. 2
“your message”
“fd64$%533#$$1”
“your message”
bob

37. 2
alicebob

38. 2
“your message”
bob alice

39. 2
“your message”
“fd64$%533#$$1”
bob alice

40. 2
“your message”
“fd64$%533#$$1”
bob
“fd64$%533#$$1”
alice

41. 2
“your message”
“fd64$%533#$$1”
“your message”
bob
“fd64$%533#$$1”
?
alice

42. 2
“your message”
“fd64$%533#$$1”
“your message”
bob
“fd64$%533#$$1”
?
alice

43. 2
alicebob
key exchange

44. what is ssl?
how we communicate securely on
the internet.
the combination of encryption and
key exchange.

45. got it?

46. got it?
(just kidding)

47. let’s build ssl

48. encryption

49. I have a message that
I want to keep secret

50. I have an encryption key
that only I know

51. I have an encryption key
that only I know

52. I have an encryption key
that only I know

53. I have an encryption key
that only I knowwhat is this thing?

54. I have an encryption key
that only I knowwhat is this thing?

55. I have an encryption key
that only I knowwhat is this thing?

56. I have an encryption key
that only I knowwhat is this thing?
“secret message”

57. I have an encryption key
that only I knowwhat is this thing?
“secret message”
“secret key”

58. I have an encryption key
that only I knowwhat is this thing?
“secret message”
“secret key”

59. “the message I want to keep secret”

60. “the message I want to keep secret”
“my secret key”+

61. “the message I want to keep secret”
“my secret key”+

62. “the message I want to keep secret”
“my secret key”+
“dkjf8#654&(@)(5335jJkdfd8(%&jfdc”=

63. “the message I want to keep secret”
“my secret key”+
“the message I want to keep secret”=
encrypted

64. “the message I want to keep secret”
“my secret key”+
“dkjf8#654&(@)(5335jJkdfd8(%&jfdc”=

65. “dkjf8#654&(@)(5335jJkdfd8(%&jfdc”
“my secret key”+

66. “dkjf8#654&(@)(5335jJkdfd8(%&jfdc”
“my secret key”+

67. “dkjf8#654&(@)(5335jJkdfd8(%&jfdc”
“my secret key”+
“the message I want to keep secret”=

68. “the message I want to keep secret”
“my secret key”+
decrypted
“the message I want to keep secret”=

69. “dkjf8#654&(@)(5335jJkdfd8(%&jfdc”
“my secret key”+
“the message I want to keep secret”=
“the message I want to keep secret”
“my secret key”+

70. “dkjf8#654&(@)(5335jJkdfd8(%&jfdc”
“my secret key”+
“the message I want to keep secret”=
“the message I want to keep secret”
“my secret key”+

71. encryption
decryption

72. encryption(message, encryption_key)
returns encrypted_message

73. decryption(encrypted_message, encryption_key)
returns message

74. encryption

75. key exchange

76. alicebob
how we get the same encryption key

77. alicebob
how we get the same encryption key
without me finding out

78. alicebob
how we get the same encryption key
without me finding out
or me

79. alicebob
how we get the same encryption key
without me finding out
or meor me

80. alicebob
how we get the same encryption key
without me finding out
or meor me

81. alicebob
how we get the same encryption key
without me finding out
or meor me
all communication is public

82. problem
how do two people share an
encryption key when they can’t
communicate privately.

83. solution
diffie-hellman!

84. solution
diffie-hellman…?

85. solution
math!

86. solution
math…?

87. solution
colors

88. solution
colors!

89. diffie-hellman key exchange

90. diffie-hellman key exchange
with no math and lots of colors!

91. imagine that we have an
infinite number of colors

92. imagine that we have an
infinite number of colors

93. imagine that we have an
infinite number of colors

94. imagine that we have an
infinite number of colors

95. imagine that we have an
infinite number of colors

96. imagine that we have an
infinite number of colors

97. imagine that we have an
infinite number of colors

98. imagine that we have an
infinite number of colors

99. imagine that we have an
infinite number of colors

100. imagine that we have an
infinite number of colors

101. some rules

102. some rules
easy to mix two colors to get a third

103. some rules
+
easy to mix two colors to get a third

104. some rules
+
easy to mix two colors to get a third
=

105. some rules
+
easy to mix two colors to get a third
=
impossible to figure out mixed colors

106. some rules
+
easy to mix two colors to get a third
=
impossible to figure out mixed colors
=

107. some rules
+
easy to mix two colors to get a third
=
impossible to figure out mixed colors
= +

108. some rules
+
easy to mix two colors to get a third
=
impossible to figure out mixed colors
= + ?

109. some rules
+
easy to mix two colors to get a third
=
impossible to figure out mixed colors
= + ?

110. bob
hi

111. alicebob
hi hey

112. alicebob

113. alicebob

114. alicebob

115. alicebob

116. alicebob

117. alicebob

118. alicebob

119. alicebob

120. alicebob
“I NEED TO TELL YOU A SECRET!”

121. alicebob
“I NEED TO TELL YOU A SECRET!” “LET’S DO A KEY EXCHANGE!”

122. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge

123. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge
bob and alice agree on a random color publicly

124. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge

125. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge
bob chooses a color and tells no one

126. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge
alice chooses a color and tells no one

127. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge
bob mixes his secret color with the public color and
send the combination to alice

128. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge

129. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge
alice mixes her secret color with the public color and
send the combination to bob

130. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge

131. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge
bob and alice mix their secret colors with their
partner’s blend to get a new secret color

132. everyone else
secret

133. + =
secret
everyone else
wrong

134. + =
secret
wrong
+ = wrong
everyone else

135. + =
secret
wrong
+ = wrong
+ = wrong
everyone else

136. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge

137. ssl
key exchange + encryption

138. “the message I want to keep secret”
bob

139. “the message I want to keep secret”
+
bob

140. encrypt
“the message I want to keep secret”
+
bob

141. “dkjf8#654&(@)(5335jJkdfd8(%&jfdc”
“the message I want to keep secret”
+

142. alicebob
bob’s knowledge alice’s knowledge
everyone’s knowledge
secret message

143. alice
“dkjf8#654&(@)(5335jJkdfd8(%&jfdc”

144. alice
“dkjf8#654&(@)(5335jJkdfd8(%&jfdc”
+

145. alice
“dkjf8#654&(@)(5335jJkdfd8(%&jfdc”
+
decrypt

146. alice
“dkjf8#654&(@)(5335jJkdfd8(%&jfdc”
+
“the message I want to keep secret”=

147. alicebob
we did it!

148. what is ssl?
how we communicate securely on
the internet.
the combination of encryption and
key exchange.

149. questions?
@jessepollak