Dissection-BKW CRYPTO 2018, Santa Barbara , August 20th 2018 Andre - - PowerPoint PPT Presentation

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Dissection-BKW CRYPTO 2018, Santa Barbara , August 20th 2018 Andre - - PowerPoint PPT Presentation

Dissection-BKW CRYPTO 2018, Santa Barbara , August 20th 2018 Andre Esser , Felix Heuer, Robert Kbler, Alexander May, Christian Sohler Horst Grtz Institute for IT Security Ruhr University Bochum What is LPN? Learning Parity with Noise (LPN)


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SLIDE 1

Dissection-BKW

CRYPTO 2018, Santa Barbara, August 20th 2018 Andre Esser, Felix Heuer, Robert Kübler, Alexander May, Christian Sohler Horst Görtz Institute for IT Security Ruhr University Bochum

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SLIDE 2

What is LPN? Learning Parity with Noise (LPN) Problem

Given: (ai, ai, s + ei), ai

$

← Fk

2, Pr[ei = 1] = τ < 1 2

Find: s ∈ Fk

2

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 2/13

slide-3
SLIDE 3

What is LPN? Learning Parity with Noise (LPN) Problem

Given: (ai, ai, s + ei), ai

$

← Fk

2, Pr[ei = 1] = τ < 1 2

Find: s ∈ Fk

2

  • Cryptographic applications [HB01, Ale03, HKL+12, DV13]

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 2/13

slide-4
SLIDE 4

What is LPN? Learning Parity with Noise (LPN) Problem

Given: (ai, ai, s + ei), ai

$

← Fk

2, Pr[ei = 1] = τ < 1 2

Find: s ∈ Fk

2

  • Cryptographic applications [HB01, Ale03, HKL+12, DV13]
  • Solve LPN: BKW algorithm [BKW00]
  • Time = Memory = Samples, slightly subexponential
  • only small experiments [BTV16, EKM17]

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 2/13

slide-5
SLIDE 5

What is LPN? Learning Parity with Noise (LPN) Problem

Given: (ai, ai, s + ei), ai

$

← Fk

2, Pr[ei = 1] = τ < 1 2

Find: s ∈ Fk

2

  • Cryptographic applications [HB01, Ale03, HKL+12, DV13]
  • Solve LPN: BKW algorithm [BKW00]
  • Time = Memory = Samples, slightly subexponential
  • only small experiments [BTV16, EKM17]
  • Goal: BKW-variant applicable for any given memory

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 2/13

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SLIDE 6

Illustration of “BKW”

(a1, a1, s + e1) (a2, a2, s + e2)

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 7

Illustration of “BKW”

(a1, a1, s + e1) (a2, a2, s + e2) + = (a1 + a2, a1 + a2, s + e1 + e2) a′ a′, s e′ ) ( , +

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 8

Illustration of “BKW”

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

slide-9
SLIDE 9

Illustration of “BKW”

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 10

Illustration of “BKW”

0101

$

0101

$

stripe

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 11

Illustration of “BKW”

0101

$

0101

$

stripe 0000

$

+

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

slide-12
SLIDE 12

Illustration of “BKW”

0000

$

0101

$

0101

$

1111

$

1111

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 13

Illustration of “BKW”

0101

$

0101

$

1111

$

1111

$

0000

$

0000

$

+

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

slide-14
SLIDE 14

Illustration of “BKW”

0101

$

0101

$

1111

$

1111

$

0000

$

0000

$

0000

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

slide-15
SLIDE 15

Illustration of “BKW”

0101

$

0101

$

1111

$

1111

$

0000

$

0000

$

0000

$

0000

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

slide-16
SLIDE 16

Illustration of “BKW”

0101

$

0101

$

1111

$

1111

$

0000

$

0000

$

0000

$

0000

$

. . . . . . . . . 0000

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 17

Illustration of “BKW”

$ $ $ $

. . . . . . . . .

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 18

Illustration of “BKW”

$ $ $ $

. . . . . . . . .

$

$ $ $ $

. . . . . . . . .

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 19

Illustration of “BKW”

$ $ $ $

. . . . . . . . .

$

$ $ $ $

. . . . . . . . .

$

→ 1 1 1 1 . . . . . . . . . 1

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 20

Illustration of “BKW”

$ $ $ $

. . . . . . . . .

$

$ $ $ $

. . . . . . . . .

$

→ 1 1 1 1 . . . . . . . . . 1

  • ai = (1, 0, 0, . . . , 0) ⇒ (ai, ai, s + ei) = (ai, s1 + ei)
  • Majority vote!

BKW Theorem [BKW00, LF06]

BKW solves LPN in time, memory and sample complexity 2k/ log k.

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 3/13

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SLIDE 21

c-sum Observation

0101

$

0101

$

0000

$

+

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 4/13

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SLIDE 22

c-sum Observation

0101

$

0101

$

0000

$

+ 0000

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 4/13

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SLIDE 23

c-sum Observation

0101

$

0101

$

0000

$

+ 0000

$

number of c-sums increases exponentially in c ⇒ much smaller list (save Memory & Samples)

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 4/13

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SLIDE 24

c-sum Observation

0101

$

0101

$

0000

$

+ 0000

$

number of c-sums increases exponentially in c ⇒ much smaller list (save Memory & Samples)

c-sum-Problem (c-SP)

Given a list L of N uniformly distributed elements from Fb

2.

Find N combinations of c elements from L that each add up to 0b.

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 4/13

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SLIDE 25

c-sum Observation

0101

$

0101

$

0000

$

+ 0000

$

number of c-sums increases exponentially in c ⇒ much smaller list (save Memory & Samples)

N c

  • /2b

!

≥ N

c-sum-Problem (c-SP)

Given a list L of N uniformly distributed elements from Fb

2.

Find N combinations of c elements from L that each add up to 0b.

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 4/13

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SLIDE 26

c-sum Observation

0101

$

0101

$

0000

$

+ 0000

$

number of c-sums increases exponentially in c ⇒ much smaller list (save Memory & Samples)

N ≥ 2b/(c−1)

c-sum-Problem (c-SP)

Given a list L of N uniformly distributed elements from Fb

2.

Find N combinations of c elements from L that each add up to 0b.

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 4/13

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SLIDE 27

c-sum Observation

0101

$

0101

$

0000

$

+ 0000

$

number of c-sums increases exponentially in c ⇒ much smaller list (save Memory & Samples)

N = 2b/(c−1)

c-sum-Problem (c-SP)

Given a list L of N uniformly distributed elements from Fb

2.

Find N combinations of c elements from L that each add up to 0b.

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 4/13

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SLIDE 28

c-sum Observation

0101

$

0101

$

0000

$

+ 0000

$

number of c-sums increases exponentially in c ⇒ much smaller list (save Memory & Samples)

N = 2b/(c−1)

Main Idea: solve c-SP repeatedly on stripes c-sum-Problem (c-SP)

Given a list L of N uniformly distributed elements from Fb

2.

Find N combinations of c elements from L that each add up to 0b.

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 4/13

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SLIDE 29

Not just a memory reduction technique

0101

$

0101

$ $

+

■t❡r❛t✐♦♥s ■t❡r❛t✐♦♥s

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 30

Not just a memory reduction technique

0101

$

0101

$ $

+ $ → $ → $ → 1

■t❡r❛t✐♦♥s ■t❡r❛t✐♦♥s

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 31

Not just a memory reduction technique

0101

$

0101

$ $

+ $ → $ → $ → 1 sum of A = 2#■t❡r❛t✐♦♥s samples

■t❡r❛t✐♦♥s

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 32

Not just a memory reduction technique

0101

$

0101

$ $

+ 0000

$

$ → $ → $ → 1 sum of A = 2#■t❡r❛t✐♦♥s samples

■t❡r❛t✐♦♥s

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 33

Not just a memory reduction technique

0101

$

0101

$ $

+ 0000

$

$ → $ → $ → 1 sum of A = 2#■t❡r❛t✐♦♥s samples

■t❡r❛t✐♦♥s

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 34

Not just a memory reduction technique

0101

$

0101

$ $

+ 0000

$

■t❡r❛t✐♦♥s

$ → $ → $ → 1 sum of B = 3#■t❡r❛t✐♦♥s samples

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 35

Not just a memory reduction technique

+ 1010101

$

0100101

$

1110000

$ $

■t❡r❛t✐♦♥s

$ → $ → $ → 1 sum of B = 3#■t❡r❛t✐♦♥s samples

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 36

Not just a memory reduction technique

+ 1010101

$

0100101

$

1110000

$ $

■t❡r❛t✐♦♥s

$

■t❡r❛t✐♦♥s

→ $ → 1

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 37

Not just a memory reduction technique

+ 1010101

$

0100101

$

1110000

$ $

■t❡r❛t✐♦♥s

$

■t❡r❛t✐♦♥s

→ $ → 1 sum of A samples

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 38

Not just a memory reduction technique

+ 1010101

$

0100101

$

1110000

$ $

■t❡r❛t✐♦♥s ■t❡r❛t✐♦♥s

sum of A samples $ → $ → 1

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 5/13

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SLIDE 39

$ → $ → 1 ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 6/13

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SLIDE 40

$ → $ → 1 N ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 6/13

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SLIDE 41

$ → $ → 1 N solve c-SP ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 6/13

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SLIDE 42

$ → $ → 1 N solve c-SP Memory ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 6/13

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SLIDE 43

$ → $ → 1 N Memory Time solve c-SP ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 6/13

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SLIDE 44

$ → $ → 1 N Memory Time solve c-SP

c-sum-BKW Theorem

LPN can be solved in time T and memory/samples M: T = Tc-SP ❛♥❞ M = N

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 6/13

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SLIDE 45

A naive Algorithm solving the c-sum-Problem c-sum-naive Algorithm

Input : list L of size N foreach (c − 1)-sum x of L do if x ∈ L then save c-sum ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 7/13

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SLIDE 46

A naive Algorithm solving the c-sum-Problem c-sum-naive Algorithm

Input : list L of size N foreach (c − 1)-sum x of L do if x ∈ L then save c-sum

c-sum-naive Theorem

c-sum-naive solves the c-sum-Problem in time T and Memory M: T = Nc−1 ❛♥❞ M = N

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 7/13

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SLIDE 47

First TMTO for BKW c-sum-naive-BKW Theorem

c-sum-naive-BKW solves LPN in time T and memory/samples M: log T = log c · k log k ❛♥❞ log M = log c c − 1 · k log k

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 8/13

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SLIDE 48

First TMTO for BKW c-sum-naive-BKW Theorem

c-sum-naive-BKW solves LPN in time T and memory/samples M: log T = log c · k log k ❛♥❞ log M = log c c − 1 · k log k

0.2 0.4 0.6 0.8 1 1 2 3 4 BKW M T

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 8/13

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SLIDE 49

First TMTO for BKW c-sum-naive-BKW Theorem

c-sum-naive-BKW solves LPN in time T and memory/samples M: log T = log c · k log k ❛♥❞ log M = log c c − 1 · k log k

0.2 0.4 0.6 0.8 1 1 2 3 4 M T

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 8/13

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SLIDE 50

First TMTO for BKW c-sum-naive-BKW Theorem

c-sum-naive-BKW solves LPN in time T and memory/samples M: log T = log c · k log k ❛♥❞ log M = log c c − 1 · k log k

0.2 0.4 0.6 0.8 1 1 2 3 4 M T

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 8/13

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SLIDE 51

The Idea of Schroeppel-Shamir

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-52
SLIDE 52

The Idea of Schroeppel-Shamir

$

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-53
SLIDE 53

The Idea of Schroeppel-Shamir

$ $ $ $ $

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

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SLIDE 54

The Idea of Schroeppel-Shamir

$ $ $ $

+

$ 00

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-55
SLIDE 55

The Idea of Schroeppel-Shamir

$ $ $ $

+

$ 00

+

$ 00

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-56
SLIDE 56

The Idea of Schroeppel-Shamir

$ $ $ $

+

$ 00

+

$ 00

+ Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-57
SLIDE 57

The Idea of Schroeppel-Shamir

$ $ $ $

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-58
SLIDE 58

The Idea of Schroeppel-Shamir

$ $ $ $

+

$ 01

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-59
SLIDE 59

The Idea of Schroeppel-Shamir

$ $ $ $

+

$ 01

+

$ 01

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-60
SLIDE 60

The Idea of Schroeppel-Shamir

$ $ $ $

+

$ 01

+

$ 01

+ Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-61
SLIDE 61

The Idea of Schroeppel-Shamir

$ $ $ $

+

$ t

+

$ t

+

. . . Repeat for all t

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-62
SLIDE 62

The Idea of Schroeppel-Shamir

$ $ $ $

+

$ t

+

$ t

+

Repeat for all t . . .

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-63
SLIDE 63

The Idea of Schroeppel-Shamir

$ $ $ $

+

$ t

+

$ t

+

Repeat for all t . . . N N

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 9/13

slide-64
SLIDE 64

Better TMTO for BKW Schroeppel-Shamir Theorem [SS81, HGJ10]

Schroeppel-Shamir solves the 4-sum Problem in time T, memory M: T = N2 ❛♥❞ M = N ❛♥❞ ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-65
SLIDE 65

Better TMTO for BKW Schroeppel-Shamir Theorem [SS81, HGJ10]

Schroeppel-Shamir solves the 4-sum Problem in time T, memory M: T = N2 ❛♥❞ M = N naive: T = N3 ❛♥❞ ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-66
SLIDE 66

Better TMTO for BKW Schroeppel-Shamir Theorem [SS81, HGJ10]

Schroeppel-Shamir solves the 4-sum Problem in time T, memory M: T = N2 ❛♥❞ M = N naive: T = N3

Dissection Theorem [DDKS12]

Dissection solves the c-sum Problem in time T and memory M: T = Nc−√c ❛♥❞ M = N ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-67
SLIDE 67

Better TMTO for BKW Schroeppel-Shamir Theorem [SS81, HGJ10]

Schroeppel-Shamir solves the 4-sum Problem in time T, memory M: T = N2 ❛♥❞ M = N naive: T = N3

Dissection Theorem [DDKS12]

Dissection solves the c-sum Problem in time T and memory M: T = Nc−√c ❛♥❞ M = N naive: T = Nc−1 ❛♥❞

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-68
SLIDE 68

Better TMTO for BKW Dissection-BKW Theorem

Dissection-BKW solves LPN in time T and memory/samples M: log T =

  • 1 − 2/√c
  • · log c ·

k log k ❛♥❞ log M = log c c − 1 · k log k

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-69
SLIDE 69

Better TMTO for BKW Dissection-BKW Theorem

Dissection-BKW solves LPN in time T and memory/samples M: log T =

  • 1 − 2/√c
  • · log c ·

k log k ❛♥❞ log M = log c c − 1 · k log k

0.2 0.4 0.6 0.8 1 1 2 3 4 M T c-sum-naive-BKW

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-70
SLIDE 70

Better TMTO for BKW Dissection-BKW Theorem

Dissection-BKW solves LPN in time T and memory/samples M: log T =

  • 1 − 2/√c
  • · log c ·

k log k ❛♥❞ log M = log c c − 1 · k log k

0.2 0.4 0.6 0.8 1 1 2 3 4 M T c-sum-naive-BKW Dissection-BKW

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-71
SLIDE 71

Better TMTO for BKW Dissection-BKW Theorem

Dissection-BKW solves LPN in time T and memory/samples M: log T =

  • 1 − 2/√c
  • · log c ·

k log k ❛♥❞ log M = log c c − 1 · k log k

0.2 0.4 0.6 0.8 1 1 2 3 4 M T c-sum-naive-BKW Dissection-BKW

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-72
SLIDE 72

Better TMTO for BKW Dissection-BKW Theorem

Dissection-BKW solves LPN in time T and memory/samples M: log T =

  • 1 − 2/√c
  • · log c ·

k log k ❛♥❞ log M = log c c − 1 · k log k

0.2 0.4 0.6 0.8 1 1 2 3 4 M T c-sum-naive-BKW Dissection-BKW

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-73
SLIDE 73

Better TMTO for BKW Dissection-BKW Theorem

Dissection-BKW solves LPN in time T and memory/samples M: log T =

  • 1 − 2/√c
  • · log c ·

k log k ❛♥❞ log M = log c c − 1 · k log k

0.2 0.4 0.6 0.8 1 1 2 3 4 M T c-sum-naive-BKW Dissection-BKW

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 10/13

slide-74
SLIDE 74

Tailored Schroeppel-Shamir

$ $ $ $

+

$ t

+

$ t

+

. . .

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 11/13

slide-75
SLIDE 75

Tailored Schroeppel-Shamir

+

$ t

+

$ t

+

. . . $ $ $ $

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 11/13

slide-76
SLIDE 76

Tailored Schroeppel-Shamir

+

. . . $ $ $ $

+

$ t′

+

$ t′

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 11/13

slide-77
SLIDE 77

Tailored Schroeppel-Shamir

$ $ $ $

+

$ t′

+

$ t′

+ Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 11/13

slide-78
SLIDE 78

Tailored Schroeppel-Shamir

$ $ $ $

+

$ t′

+

$ t′

+ Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 11/13

slide-79
SLIDE 79

Tailored Schroeppel-Shamir

$ $ $ $

+

$ t′

+

$ t′

+

. . . Repeat for all t′

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 11/13

slide-80
SLIDE 80

Tailored Schroeppel-Shamir

$ $ $ $

+

$ t′

+

$ t′

+

Repeat for all t′ enough

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 11/13

slide-81
SLIDE 81

Tailored Schroeppel-Shamir

$ $ $ $

+

$ t′

+

$ t′

+

Repeat for all t′ enough N′ N′

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 11/13

slide-82
SLIDE 82

A continous TMTO via tailored Dissection

0.2 0.4 0.6 0.8 1 1 2 3 4 M T c-sum-naive-BKW Dissection-BKW

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 12/13

slide-83
SLIDE 83

A continous TMTO via tailored Dissection

0.2 0.4 0.6 0.8 1 1 2 3 4 M T c-sum-naive-BKW Dissection-BKW Tailored-Diss.-BKW

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 12/13

slide-84
SLIDE 84

A continous TMTO via tailored Dissection

0.2 0.4 0.6 0.8 1 1 2 3 4 M T c-sum-naive-BKW Dissection-BKW Tailored-Diss.-BKW

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 12/13

slide-85
SLIDE 85

Results

  • BKW-variant applicable for any given amount of memory

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 13/13

slide-86
SLIDE 86

Results

  • BKW-variant applicable for any given amount of memory
  • Tailored Dissection

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 13/13

slide-87
SLIDE 87

Results

  • BKW-variant applicable for any given amount of memory
  • Tailored Dissection
  • Quantum tradeoff

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 13/13

slide-88
SLIDE 88

Results

  • BKW-variant applicable for any given amount of memory
  • Tailored Dissection
  • Quantum tradeoff
  • Tradeoffs for LWE

Dissection-BKW|CRYPTO 2018, Santa Barbara|August 20th 2018 13/13

slide-89
SLIDE 89

Results

  • BKW-variant applicable for any given amount of memory
  • Tailored Dissection
  • Quantum tradeoff
  • Tradeoffs for LWE

T h a n k y

  • u

! 2 1 8 / 5 6 9

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SLIDE 90

References I

[Ale03] Michael Alekhnovich. More on average case vs approximation complexity. In 44th FOCS, pages 298–307. IEEE Computer Society Press, October 2003. [BKW00] Avrim Blum, Adam Kalai, and Hal Wasserman. Noise-tolerant learning, the parity problem, and the statistical query model. In 32nd ACM STOC, pages 435–440. ACM Press, May 2000. [BTV16] Sonia Bogos, Florian Tramer, and Serge Vaudenay. On solving lpn using bkw and variants. Cryptography and Communications, 8(3):331–369, 2016. [DDKS12] Itai Dinur, Orr Dunkelman, Nathan Keller, and Adi Shamir. Efficient dissection

  • f composite problems, with applications to cryptanalysis, knapsacks, and com-

binatorial search problems. In Reihaneh Safavi-Naini and Ran Canetti, editors, CRYPTO 2012, volume 7417 of LNCS, pages 719–740. Springer, Heidelberg, August 2012. [DV13] Alexandre Duc and Serge Vaudenay. HELEN: A public-key cryptosystem based

  • n the LPN and the decisional minimal distance problems. In Amr Youssef,

Abderrahmane Nitaj, and Aboul Ella Hassanien, editors, AFRICACRYPT 13, volume 7918 of LNCS, pages 107–126. Springer, Heidelberg, June 2013.

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SLIDE 91

References II

[EKM17] Andre Esser, Robert Kübler, and Alexander May. LPN decoded. In Jonathan Katz and Hovav Shacham, editors, CRYPTO 2017, Part II, volume 10402 of LNCS, pages 486–514. Springer, Heidelberg, August 2017. [HB01] Nicholas J. Hopper and Manuel Blum. Secure human identification protocols. In Colin Boyd, editor, ASIACRYPT 2001, volume 2248 of LNCS, pages 52–66. Springer, Heidelberg, December 2001. [HGJ10] Nick Howgrave-Graham and Antoine Joux. New generic algorithms for hard

  • knapsacks. In Henri Gilbert, editor, EUROCRYPT 2010, volume 6110 of LNCS,

pages 235–256. Springer, Heidelberg, May / June 2010. [HKL+12] Stefan Heyse, Eike Kiltz, Vadim Lyubashevsky, Christof Paar, and Krzysztof

  • Pietrzak. Lapin: An efficient authentication protocol based on ring-LPN. In

Anne Canteaut, editor, FSE 2012, volume 7549 of LNCS, pages 346–365. Springer, Heidelberg, March 2012. [LF06] Éric Levieil and Pierre-Alain Fouque. An improved LPN algorithm. In Roberto De Prisco and Moti Yung, editors, SCN 06, volume 4116 of LNCS, pages 348–359. Springer, Heidelberg, September 2006. [SS81] Richard Schroeppel and Adi Shamir. A t=o(2ˆn/2), s=o(2ˆn/4) algorithm for certain np-complete problems. SIAM journal on Computing, 10(3):456–464, 1981.

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