Bootstrapping Mobile PINs Using Passwords

Markus JakobssonDebin Liu

Information Risk ManagementPayPal

A Bit about Authentication

2

1 2 3 4 5

Short battery life

Slow Web connection

Lack of coverage

Poor voice quality

Small screen

size

Difficulty customizing

settings

Difficulty authenticating

Commercial Four-Letter Word

“Friction”

A Bit About Human Memory

Not so amazing

Common PIN

Your spouse’s birthday

Love/Hate

PINs

What will users see

Example User Mapping

“Blu2thRules” “2582”

Opportunistic Derivation

Access; Truncate; Map; Store

Special Characters

~1.5%

Can be reduced

Special Phones

Need numeric pad

Strong password, weak PIN

“1234Brew$g”, “1begHELP”

Password change?

Dual Universes

Measuring Security

Raided Dropboxes

Entropy of Derived PINs

FSP (8359) SNP (2873) Malware (16192)0

2

4

6

8

10

12

14

12

10.59.7

10.910

9.2

1.10.5 0.5

pwd4 EntropyPIN EntropyInformation Loss by Mapping

Data Sources (Size)

Info

rmat

ion

En

trop

ies

Special Characters

FSP (8359) SNP (2873) Malware (16192)0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

35.00% 32.16%

11.14%

26.96%

1.44% 1.95%

6.16%

Percentage of Passwords using Upper Case Letters

Percentage of Passwords using Special Characters

Data Sources (Size)

Per

cen

tage

Imagine PIN Theft

0

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4

6

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10

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14

16

18

20

Experiment

What is Joe’s PIN?

Joe uses a PIN to access his PayPal account from his phone. But he does not want to have to remember another number, and he does not want to reuse his banking PIN. So he uses PayPal’s new “password to PIN” feature so that he only has to remember his password. Joe’s password is “Blu2thrules”. Look at the screen-shot below and let us know what PIN he should enter.

Usability of Derived PINs25-subject Qualitative study

Successful but Slow 24%

Failed12%

Successful and Fas

t64%

Usability of Derived PINs100-subject Quantitative study

Likely Successful22%

Failed10%

Successful68%

Other things I pitch

Address web/app spoofing: www.SpoofKiller.com

Mobile-friendly passwords: www.fastword.me

Mobile malware detection: www.fatskunk.com

Etc: www.markus-jakobsson.com