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Securing TodoMVC 
Using the 
Web Cryptography API 
Kevin Hakanson 
12 September 2014
Kevin Hakanson 
@hakanson 
+KevinHakanson 
hakanson
Project which offers the same Todo application 
implemented using MV* concepts in most of the popular 
JavaScript MV* fram...
Today's Session "todos" 
● Review some cryptography concepts 
● Look at the Web Cryptography API 
● Combine these to secur...
Supporting Materials 
(if you want to follow along) 
Presentation and Source Code 
https://github.com/hakanson/todomvc-jqu...
Why?
TodoMVC Uses localStorage 
Chrome keeps localStorage in an SQLite file: 
OS X: ~/Library/Application Support/Google/Chrome...
OWASP Top 10 2013 
● A1-Injection 
● A2-Broken Authentication and Session Management 
● A3-Cross-Site Scripting (XSS) 
● A...
A6-Sensitive Data Exposure 
Covers sensitive data protection from the 
moment sensitive data is provided by the user, 
sen...
A6-Sensitive Data Exposure 
Am I Vulnerable To 'Sensitive Data Exposure'? 
1. Is any of this data stored in clear text lon...
Acceptance Criteria 
● Enter password before accessing "todos" 
● Data encrypted "at rest" in localStorage
How?
W3C Web Cryptography API 
This specification describes a JavaScript API 
for performing basic cryptographic operations in ...
WebCryptoAPI Use Cases 
● Multi-factor Authentication 
● Protected Document Exchange 
● Cloud Storage 
● Document Signing ...
SubtleCrypto Interface 
● Provides a set of methods for dealing with 
low-level cryptographic primitives and 
algorithms. ...
Web Cryptography Working Group 
Key Dates 
○ April 2012: Group Formation 
○ March 2014: Last Call Working Draft 
○ ????: E...
Where? 
(Browser Support)
Chromium Dashboard 
Web Crypto API 
Implementation Status 
Enabled by default in desktop Chrome 37 (launch bug) 
Available...
http://caniuse.com/#search=Web 
Cryptography
IE Platform Status 
Web Crypto API 
Note: IE11 implementation based on spec before 
change from CryptoOperation to Promise...
Promises/A+ 
A promise represents the eventual result of an 
asynchronous operation. The primary way of 
interacting with ...
Chromium Dashboard 
Promises (ES6) 
Implementation Status 
Enabled by default in desktop Chrome 32 (launch bug) 
Available...
Microsoft Research JavaScript 
Cryptography Library 
● The algorithms are exposed via the W3C 
WebCrypto interface, and ar...
But...
Javascript Cryptography Considered 
Harmful (circa 2010) 
● Opinion on browser Javascript cryptography 
○ "no reliable way...
Host-Proof Hosting 
● In A Blink 
○ Sketch: Locked inside data cloud, key at browser. 
● Solution 
○ Host sensitive data i...
Host-Proof Hosting "Requirements" 
● Secure transport mechanism (HTTPS). 
● Trust provider that hosts web application and ...
My "Requirement" 
● Avoid proving "Schneier's Law" 
○ Anyone can invent a security system that he himself 
cannot break.
What? 
(concepts)
Glossary 
Glossary of Key Information Security Terms 
http://nvlpubs.nist.gov/nistpubs/ir/2013/NIST.IR.7298r2.pdf 
SOURCE:...
Cryptography 
The discipline that embodies principles, means, 
and methods for providing information security, 
including ...
Pseudorandom number generator 
(PRNG) 
An algorithm that produces a sequence of bits 
that are uniquely determined from an...
crypto.getRandomValues() 
If you provide an integer-based TypedArray, 
the function is going fill the array with 
cryptogr...
Cryptographic Hash Function 
A function that maps a bit string of arbitrary 
length to a fixed length bit string. 
Approve...
Message Digest 
The result of applying a hash function to a 
message. Also known as a “hash value” or 
“hash output”. 
SOU...
OpenSSL Command Line 
$ echo -n "The quick brown fox jumps over the 
lazy dog" | openssl dgst -sha256 
(stdin)= 
d7a8fbb30...
QUnit Test 
QUnit.test( 'SHA-256', function ( assert ) { 
var testVector = { 
data: 'The quick brown fox jumps over the la...
QUnit Extension 
QUnit.extend( QUnit.assert, { 
promise: function ( promise ) { 
var assert = this; 
QUnit.stop(); 
promis...
ex: DOMException 
code: 9 
message: "WebCrypto is only supported over secure origins. See 
http://crbug.com/373032" 
name:...
TextEncoder 
Encoding API 
Script API to allow encoding/decoding of strings from 
binary data. 
Firefox 19 
https://develo...
$.Uint8Util 
toHexString( buf : Uint8Array ) : string 
fromHexString ( s : string ) : Uint8Array 
(still looking for a bet...
$.WebCryptoAPI 
Wrapper around: 
● crypto (WebCrypto spec) 
● msCrypto (IE11) 
● msrCrypto (Microsoft Research) 
● webkitS...
Hash-based Message Authentication 
Code (HMAC) 
A message authentication code that uses a 
cryptographic key in conjunctio...
Cryptographic Key 
A parameter used in conjunction with a cryptographic 
algorithm that determines 
● the transformation o...
Symmetric Key 
A cryptographic key that is used to perform 
both the cryptographic operation and its 
inverse, for example...
Digital Signature 
The result of a cryptographic transformation of 
data which, when properly implemented, 
provides the s...
OpenSSL Command Line 
$ echo -n "The quick brown fox jumps 
over the lazy dog" | openssl dgst - 
sha256 -hmac "key" 
(stdi...
QUnit.test( 'HMAC using SHA-256', function ( assert ) { 
var testVector = { 
data: 'The quick brown fox jumps over the laz...
QUnit.test( 'HMAC using SHA-256', function ( assert ) { 
var testVector = { 
data: 'The quick brown fox jumps over the laz...
QUnit.test( 'HMAC using SHA-256', function ( assert ) { 
var testVector = { 
data: 'The quick brown fox jumps over the laz...
KJH-256 Hash 
QUnit.test( 'KJH-256', function ( assert ) { 
var testVector = { 
data: 'The quick brown fox jumps over the ...
Error Results 
IE 11 
NotSupportedError 
Chrome 37 
Algorithm: Unrecognized name 
Firefox 35 
An invalid or illegal string...
QUnit.test( 'HMAC using KJH-256', function ( assert ) { 
var testVector = { 
data: 'The quick brown fox jumps over the laz...
Error Results 
IE 11 
failed, expected argument to be truthy, was: false 
Chrome 37 
HmacImportParams: hash: Algorithm: Un...
Cipher, Plaintext and Ciphertext 
Cipher - Series of transformations that 
converts plaintext to ciphertext using the 
Cip...
AES 
The Advanced Encryption Standard specifies a 
U.S. government approved cryptographic 
algorithm that can be used to p...
(CC BY 3.0) http://www.moserware.com/2009/09/stick-figure-guide-to-advanced.html
Initialization Vector (IV) 
A vector used in defining the starting point of an 
encryption process within a cryptographic ...
OpenSSL Command Line 
$ echo -n "Message" | openssl enc - 
aes256 -K 
0CD1D07EB67E19EF56EA0F3A9A8F8A7C957A2C 
B208327E0E53...
QUnit.test( 'AES-CBC', function ( assert ) { 
var testVector = { 
plaintext: 'Message', 
iv: '6C4C31BDAB7BAFD35B23691EC521...
assert.promise( crypto.subtle.importKey( 'raw', keyBuf, { name: 'AES-CBC' }, 
true, ['encrypt', 'decrypt'] ) 
.then( funct...
assert.promise( crypto.subtle.importKey( 'raw', keyBuf, { name: 'AES-CBC' }, 
true, ['encrypt', 'decrypt'] ) 
.then( funct...
assert.promise( crypto.subtle.importKey( 'raw', keyBuf, { name: 'AES-CBC' }, 
true, ['encrypt', 'decrypt'] ) 
.then( funct...
redux 
chained vs. nested promises
function importKey () { 
return crypto.subtle.importKey( 'raw', keyBuf, { name: 'AES-CBC' }, 
true, ['encrypt', 'decrypt']...
function compare ( decryptResult ) { 
var plaintext = decoder.decode( new Uint8Array( decryptResult ) ); 
assert.equal( pl...
Password-Based Key Derivation 
Functions (PBKDF) 
● The randomness of cryptographic keys is 
essential for the security of...
Password-Based Key Derivation 
Functions (PBKDF) 
● The randomness of cryptographic keys is 
essential for the security of...
Password-Based Key Derivation 
Functions (PBKDF) 
● The randomness of cryptographic keys is 
essential for the security of...
Salt 
A non-secret value that is used in a 
cryptographic process, usually to ensure that 
the results of computations for...
PBKDF Specification 
Input: 
P Password 
S Salt 
C Iteration count 
kLen Length of MK in bits; at most (232-1) x hLen 
Par...
QUnit.test( 'PBKDF2', function ( assert ) { 
var testVector = { 
password : 'password', 
salt: 'cf7488cd1e48e84990f51b3f12...
var passwordBuf = decoder.decode( testVector.password ); 
assert.promise( crypto.subtle.importKey('raw', passwordBuf, 'PBK...
var passwordBuf = decoder.decode( testVector.password ); 
assert.promise( crypto.subtle.importKey('raw', passwordBuf, 'PBK...
Data Flow and Storage (expected) 
● Salt = initial random 
● IV = initial random 
● Ciphertext = AES( todos, Key, IV )
Data Flow and Storage (actual) 
● PBKDF2 only implemented in Firefox 33 
● Substitute HMAC to generate 256 bit key 
○ (do ...
Set and Confirm Password 
On first use, password must be established.
Password Entry Field 
<header id="header"> 
<h1><span>secure</span> todos</h1> 
<input id="new-todo" 
placeholder="What ne...
Render Password Entry Field 
render: function () { 
var todos, placeholder; 
if (this.todos) { 
this.$password.addClass('h...
Enter and Validate Password 
On subsequent uses, password must be 
entered to unlock todos. 
An invalid password will shak...
CSS3 Shake Animation 
#todo-password.invalid { 
margin-left: 50px; 
padding: 3px 3px 3px 7px; 
border: 3px solid; 
width: ...
Demo
validatePassword: function (password, confirmPassword) { 
var that = this; 
if (confirmPassword && confirmPassword != pass...
Convert store to return a Promise 
store: function (data) { 
if (data) { 
return cryptoStorage.setItem(data); 
} else { 
r...
Data Flow and Storage (API)
Random IV and Salt 
if ( !this.initialized ) { 
this.salt = new Uint8Array( 32 ); 
$.WebCryptoAPI.getRandomValues( this.sa...
Generate Key from Password 
return $.WebCryptoAPI.subtle.importKey('raw', this.salt, hmacSha256, 
true, ['sign', 'verify']...
Generate Key from Password 
return $.WebCryptoAPI.subtle.importKey('raw', this.salt, hmacSha256, 
true, ['sign', 'verify']...
Generate Key from Password 
return $.WebCryptoAPI.subtle.importKey('raw', this.salt, hmacSha256, 
true, ['sign', 'verify']...
Generate Key from Password 
return $.WebCryptoAPI.subtle.importKey('raw', this.salt, hmacSha256, 
true, ['sign', 'verify']...
Encrypt and Store 
var encoder = new TextEncoder(); 
var todosBuf = encoder.encode(JSON.stringify(value)); 
var aesCbc = {...
Decrypt 
var todosBuf = $.Uint8Util.fromHexString(data.ciphertext); 
var aesCbc = {name: 'AES-CBC', iv: this.iv }; 
$.WebC...
Encrypted in localStorage 
sqlite> select * from ItemTable; 
todos-jquery-webcryptoapi|{"salt":" 
455ad2b6be02de86226c8c10...
Questions? 
(and hopefully answers)
Securing TodoMVC Using the Web Cryptography API
Securing TodoMVC Using the Web Cryptography API
Securing TodoMVC Using the Web Cryptography API
Securing TodoMVC Using the Web Cryptography API
Securing TodoMVC Using the Web Cryptography API
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Securing TodoMVC Using the Web Cryptography API

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The open source TodoMVC project implements a Todo application using popular JavaScript MV* frameworks. Some of the implementations add support for compile to JavaScript languages, module loaders and real time backends. This presentation will demonstrate a TodoMVC implementation which adds support for the forthcoming W3C Web Cryptography API, as well as review some key cryptographic concepts and definitions.

Instead of storing the Todo list as plaintext in localStorage, this "secure" TodoMVC implementation encrypts Todos using a password derived key. The PBKDF2 algorithm is used for the deriveKey operation, with getRandomValues generating a cryptographically random salt. The importKey method sets up usage of AES-CBC for both encrypt and decrypt operations. The final solution helps address item "A6-Sensitive Data Exposure" from the OWASP Top 10.

With the Web Cryptography API being a recommendation in 2014, any Q&A time will likely include browser implementations and limitations, and whether JavaScript cryptography adds any value.

Publié dans : Technologie

Securing TodoMVC Using the Web Cryptography API

  1. 1. Securing TodoMVC Using the Web Cryptography API Kevin Hakanson 12 September 2014
  2. 2. Kevin Hakanson @hakanson +KevinHakanson hakanson
  3. 3. Project which offers the same Todo application implemented using MV* concepts in most of the popular JavaScript MV* frameworks of today. http://todomvc.com/ https://github.com/tastejs/todomvc
  4. 4. Today's Session "todos" ● Review some cryptography concepts ● Look at the Web Cryptography API ● Combine these to secure TodoMVC
  5. 5. Supporting Materials (if you want to follow along) Presentation and Source Code https://github.com/hakanson/todomvc-jquery-webcryptoapi Demo https://hakanson.github.io/todomvc-jquery-webcryptoapi
  6. 6. Why?
  7. 7. TodoMVC Uses localStorage Chrome keeps localStorage in an SQLite file: OS X: ~/Library/Application Support/Google/Chrome/Default/Local Storage Windows: %HOMEPATH%AppDataLocalGoogleChromeUser DataDefaultLocal Storage $ sqlite3 http_todomvc.com_0.localstorage sqlite> select * from ItemTable; todos-jquery|[{"id":"c8f7b7e1-88bf-451b-8aff- 04c9ac2544aa","title":"secure using Web Cryptography API","completed":false}]
  8. 8. OWASP Top 10 2013 ● A1-Injection ● A2-Broken Authentication and Session Management ● A3-Cross-Site Scripting (XSS) ● A4-Insecure Direct Object References ● A5-Security Misconfiguration ● A6-Sensitive Data Exposure ● A7-Missing Function Level Action Control ● A8-Cross-Site Request Forgery (CSRF) ● A9-Using Components with Known Vulnerabilities ● A10-Unvalidated Redirects and Forwards https://www.owasp.org/index.php/Top_10_2013
  9. 9. A6-Sensitive Data Exposure Covers sensitive data protection from the moment sensitive data is provided by the user, sent to and stored within the application, and then sent back to the browser again.
  10. 10. A6-Sensitive Data Exposure Am I Vulnerable To 'Sensitive Data Exposure'? 1. Is any of this data stored in clear text long term, including backups of this data? 2. … 3. … 4. … 5. … https://www.owasp.org/index.php/Top_10_2013-A6
  11. 11. Acceptance Criteria ● Enter password before accessing "todos" ● Data encrypted "at rest" in localStorage
  12. 12. How?
  13. 13. W3C Web Cryptography API This specification describes a JavaScript API for performing basic cryptographic operations in web applications, such as hashing, signature generation and verification, and encryption and decryption. http://www.w3.org/TR/WebCryptoAPI/
  14. 14. WebCryptoAPI Use Cases ● Multi-factor Authentication ● Protected Document Exchange ● Cloud Storage ● Document Signing ● Data Integrity Protection ● Secure Messaging ● Javascript Object Signing and Encryption (JOSE) http://www.w3.org/TR/WebCryptoAPI/#use-cases
  15. 15. SubtleCrypto Interface ● Provides a set of methods for dealing with low-level cryptographic primitives and algorithms. ● Named SubtleCrypto to reflect the fact that many of these algorithms have subtle usage requirements in order to provide the required algorithmic security guarantees.
  16. 16. Web Cryptography Working Group Key Dates ○ April 2012: Group Formation ○ March 2014: Last Call Working Draft ○ ????: Expected Candidate Recommendation ○ ????: Expected Proposed Recommendation ○ 2015: Expected Recommendation http://www.w3.org/2012/webcrypto/Overview.html
  17. 17. Where? (Browser Support)
  18. 18. Chromium Dashboard Web Crypto API Implementation Status Enabled by default in desktop Chrome 37 (launch bug) Available in Chrome for Android release 37. Consensus & Standardization ● Firefox: In development ● Internet Explorer: In development ● Opera: Shipped in release 24 ● Opera for Android: Shipped in release 24 ● Safari: In development ● Web Developers: Mixed signals
  19. 19. http://caniuse.com/#search=Web Cryptography
  20. 20. IE Platform Status Web Crypto API Note: IE11 implementation based on spec before change from CryptoOperation to Promise based API
  21. 21. Promises/A+ A promise represents the eventual result of an asynchronous operation. The primary way of interacting with a promise is through its then method, which registers callbacks to receive either a promise's eventual value or the reason why the promise cannot be fulfilled.
  22. 22. Chromium Dashboard Promises (ES6) Implementation Status Enabled by default in desktop Chrome 32 (launch bug) Available in Chrome for Android release 32. Consensus & Standardization ● Firefox: Shipped ● Internet Explorer: Public support ● Opera: Shipped in release 19 ● Opera for Android: Shipped in release 19 ● Safari: In development ● Web Developers: Mixed signals
  23. 23. Microsoft Research JavaScript Cryptography Library ● The algorithms are exposed via the W3C WebCrypto interface, and are tested against the Internet Explorer 11 implementation of that interface. ● This library is under active development. Future updates to this library may change the programming interfaces. Date Published: 17 June 2014
  24. 24. But...
  25. 25. Javascript Cryptography Considered Harmful (circa 2010) ● Opinion on browser Javascript cryptography ○ "no reliable way for any piece of Javascript code to verify its execution environment" ○ "can't outsource random number generation in a cryptosystem" ○ "practically no value to doing crypto in Javascript once you add SSL to the mix" ○ "store the key on that server [and] documents there" http://www.matasano.com/articles/javascript-cryptography/ ● Didn't consider the "offline" user experience
  26. 26. Host-Proof Hosting ● In A Blink ○ Sketch: Locked inside data cloud, key at browser. ● Solution ○ Host sensitive data in encrypted form, so that clients can only access and manipulate it by providing a pass-phrase which is never transmitted to the server. ○ All encryption and decryption takes place inside the browser itself. http://ajaxpatterns.org/Host-Proof_Hosting (July 2005)
  27. 27. Host-Proof Hosting "Requirements" ● Secure transport mechanism (HTTPS). ● Trust provider that hosts web application and serves HTML and JavaScript resources. ● Defend against and accept risk of script injection (XSS) threat. ○ However, unauthorized access by hackers only attacks users who access the application while infected, and not the entire persisted data store.
  28. 28. My "Requirement" ● Avoid proving "Schneier's Law" ○ Anyone can invent a security system that he himself cannot break.
  29. 29. What? (concepts)
  30. 30. Glossary Glossary of Key Information Security Terms http://nvlpubs.nist.gov/nistpubs/ir/2013/NIST.IR.7298r2.pdf SOURCE: NISTIR 7298
  31. 31. Cryptography The discipline that embodies principles, means, and methods for providing information security, including confidentiality, data integrity, non-repudiation, and authenticity. SOURCE: SP 800-21
  32. 32. Pseudorandom number generator (PRNG) An algorithm that produces a sequence of bits that are uniquely determined from an initial value called a seed. The output of the PRNG “appears” to be random. A cryptographic PRNG has the additional property that the output is unpredictable, given that the seed is not known. SOURCE: CNSSI-4009
  33. 33. crypto.getRandomValues() If you provide an integer-based TypedArray, the function is going fill the array with cryptographically random numbers. var buf = new Uint8Array(32); window.crypto.getRandomValues(buf); https://developer.mozilla.org/en-US/docs/DOM/window.crypto.getRandomValues http://msdn.microsoft.com/en-us/library/ie/dn302324(v=vs.85).aspx
  34. 34. Cryptographic Hash Function A function that maps a bit string of arbitrary length to a fixed length bit string. Approved hash functions satisfy the following properties: ● One-way ● Collision resistant SOURCE: SP 800-21
  35. 35. Message Digest The result of applying a hash function to a message. Also known as a “hash value” or “hash output”. SOURCE: SP 800-107
  36. 36. OpenSSL Command Line $ echo -n "The quick brown fox jumps over the lazy dog" | openssl dgst -sha256 (stdin)= d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb76 2d02d0bf37c9e592
  37. 37. QUnit Test QUnit.test( 'SHA-256', function ( assert ) { var testVector = { data: 'The quick brown fox jumps over the lazy dog', sha256Hash : 'd7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592' }; var encoder = new TextEncoder(); var dataBuf = encoder.encode( testVector.data ); assert.promise( crypto.subtle.digest( { name: 'sha-256' }, dataBuf ) .then( function (result) { var hash = $.Uint8Util.toHexString( new Uint8Array( result ) ); assert.equal( hash, testVector.sha256Hash ); })); });
  38. 38. QUnit Extension QUnit.extend( QUnit.assert, { promise: function ( promise ) { var assert = this; QUnit.stop(); promise.catch( function ( err ) { assert.ok( false, err.message ); }).then( function ( ) { QUnit.start(); }); } });
  39. 39. ex: DOMException code: 9 message: "WebCrypto is only supported over secure origins. See http://crbug.com/373032" name: "NotSupportedError" __proto__: DOMException For example these are considered secure origins: ● chrome-extension://xxx ● https://xxx ● wss://xxx ● file://xxx ● http://localhost/ ● http://127.0.0.1/ Whereas these are considered insecure: ● http://foobar ● ws://foobar
  40. 40. TextEncoder Encoding API Script API to allow encoding/decoding of strings from binary data. Firefox 19 https://developer.mozilla.org/en-US/docs/Web/API/TextEncoder Intent to Ship in Chrome 38 Issue 243354: Implement Text Encoding API Polyfill https://github.com/inexorabletash/text-encoding
  41. 41. $.Uint8Util toHexString( buf : Uint8Array ) : string fromHexString ( s : string ) : Uint8Array (still looking for a better way)
  42. 42. $.WebCryptoAPI Wrapper around: ● crypto (WebCrypto spec) ● msCrypto (IE11) ● msrCrypto (Microsoft Research) ● webkitSubtle (Webkit Nightly) Implemented as jQuery Utility Plugin
  43. 43. Hash-based Message Authentication Code (HMAC) A message authentication code that uses a cryptographic key in conjunction with a hash function. SOURCE: FIPS 201; CNSSI-4009
  44. 44. Cryptographic Key A parameter used in conjunction with a cryptographic algorithm that determines ● the transformation of plaintext data into ciphertext data, ● the transformation of ciphertext data into plaintext data, ● a digital signature computed from data, ● ... SOURCE: FIPS 140-2
  45. 45. Symmetric Key A cryptographic key that is used to perform both the cryptographic operation and its inverse, for example to encrypt and decrypt, or create a message authentication code and to verify the code. SOURCE: SP 800-63; CNSSI-4009
  46. 46. Digital Signature The result of a cryptographic transformation of data which, when properly implemented, provides the services of: 1. origin authentication, 2. data integrity, and 3. signer non-repudiation. SOURCE: FIPS 140-2
  47. 47. OpenSSL Command Line $ echo -n "The quick brown fox jumps over the lazy dog" | openssl dgst - sha256 -hmac "key" (stdin)= f7bc83f430538424b13298e6aa6fb143ef4d59 a14946175997479dbc2d1a3cd8
  48. 48. QUnit.test( 'HMAC using SHA-256', function ( assert ) { var testVector = { data: 'The quick brown fox jumps over the lazy dog', key: 'key', hash : 'f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8' }; var hmacSha256 = { name: 'hmac', hash: { name: 'sha-256' } }; var encoder = new TextEncoder(); var dataBuf = encoder.encode( testVector.data ); var keyBuf = encoder.encode( testVector.key ); });
  49. 49. QUnit.test( 'HMAC using SHA-256', function ( assert ) { var testVector = { data: 'The quick brown fox jumps over the lazy dog', key: 'key', hash : 'f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8' }; var hmacSha256 = { name: 'hmac', hash: { name: 'sha-256' } }; var encoder = new TextEncoder(); var dataBuf = encoder.encode( testVector.data ); var keyBuf = encoder.encode( testVector.key ); assert.promise( crypto.subtle.importKey( 'raw', keyBuf, hmacSha256, true, ['sign', 'verify'] ) .then( function ( keyResult ) { })); });
  50. 50. QUnit.test( 'HMAC using SHA-256', function ( assert ) { var testVector = { data: 'The quick brown fox jumps over the lazy dog', key: 'key', hash : 'f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8' }; var hmacSha256 = { name: 'hmac', hash: { name: 'sha-256' } }; var encoder = new TextEncoder(); var dataBuf = encoder.encode( testVector.data ); var keyBuf = encoder.encode( testVector.key ); assert.promise( crypto.subtle.importKey( 'raw', keyBuf, hmacSha256, true, ['sign', 'verify'] ) .then( function ( keyResult ) { return crypto.subtle.sign( hmacSha256, keyResult, dataBuf ) .then( function ( signResult ) { var hash = $.Uint8Util.toHexString( new Uint8Array( signResult ) ); assert.equal( hash, testVector.hash ); }) })); });
  51. 51. KJH-256 Hash QUnit.test( 'KJH-256', function ( assert ) { var testVector = { data: 'The quick brown fox jumps over the lazy dog', }; var encoder = new TextEncoder(); var dataBuf = encoder.encode( testVector.data ); assert.promise( crypto.subtle.digest( { name: 'kjh-256' }, dataBuf ) .then( function ( result ) { var hash = $.Uint8Util.toHexString( new Uint8Array( result ) ); assert.equal( hash, 'kjh' ); })); });
  52. 52. Error Results IE 11 NotSupportedError Chrome 37 Algorithm: Unrecognized name Firefox 35 An invalid or illegal string was specified Opera 24 Algorithm: Unrecognized name MSR Crypto 1.2 unsupported algorithm Webkit Nightly NotSupportedError: DOM Exception 9
  53. 53. QUnit.test( 'HMAC using KJH-256', function ( assert ) { var testVector = { data: 'The quick brown fox jumps over the lazy dog', key: 'key' }; var encoder = new TextEncoder(); var dataBuf = encoder.encode( testVector.data ); var keyBuf = encoder.encode( testVector.key ); var hmacKjh256 = { name: 'hmac', hash: { name: 'kjh-256' } }; assert.promise( crypto.subtle.importKey( 'raw', keyBuf, hmacKjh256, true, ['sign', 'verify'] ) .then( function ( keyResult ) { return crypto.subtle.sign( hmacKjh256, keyResult, dataBuf ) .then( function ( signResult ) { var hash = $.Uint8Util.toHexString( new Uint8Array( signResult ) ); assert.equal( hash, 'kjh' ); }) })); });
  54. 54. Error Results IE 11 failed, expected argument to be truthy, was: false Chrome 37 HmacImportParams: hash: Algorithm: Unrecognized name Firefox 35 An invalid or illegal string was specified Opera 24 HmacImportParams: hash: Algorithm: Unrecognized name MSR Crypto 1.2 Error: unsupported hash alorithm (sha-224, sha-256, sha-384, sha-512) Webkit Nightly NotSupportedError: DOM Exception 9
  55. 55. Cipher, Plaintext and Ciphertext Cipher - Series of transformations that converts plaintext to ciphertext using the Cipher Key. See Also: Inverse Cipher SOURCE: FIPS 197
  56. 56. AES The Advanced Encryption Standard specifies a U.S. government approved cryptographic algorithm that can be used to protect electronic data. The AES algorithm is a symmetric block cipher that can encrypt (encipher) and decrypt (decipher) information. SOURCE: FIPS 197
  57. 57. (CC BY 3.0) http://www.moserware.com/2009/09/stick-figure-guide-to-advanced.html
  58. 58. Initialization Vector (IV) A vector used in defining the starting point of an encryption process within a cryptographic algorithm. SOURCE: FIPS 140-2
  59. 59. OpenSSL Command Line $ echo -n "Message" | openssl enc - aes256 -K 0CD1D07EB67E19EF56EA0F3A9A8F8A7C957A2C B208327E0E536608FF83256C96 -iv 6C4C31BDAB7BAFD35B23691EC521E28D | xxd -p 23e5ebe72d99cf302c99183c05cf050a
  60. 60. QUnit.test( 'AES-CBC', function ( assert ) { var testVector = { plaintext: 'Message', iv: '6C4C31BDAB7BAFD35B23691EC521E28D', key: '0CD1D07EB67E19EF56EA0F3A9A8F8A7C957A2CB208327E0E536608FF83256C96', ciphertext: '23e5ebe72d99cf302c99183c05cf050a' }; var encoder = new TextEncoder(); var decoder = new TextDecoder(); var buf = encoder.encode( testVector.plaintext ); var keyBuf = $.Uint8Util.fromHexString( testVector.key ); var ivBuf = $.Uint8Util.fromHexString( testVector.iv ); var aesCbc = { name: 'AES-CBC', iv: ivBuf }; // import key, encrypt, decrypt and compare });
  61. 61. assert.promise( crypto.subtle.importKey( 'raw', keyBuf, { name: 'AES-CBC' }, true, ['encrypt', 'decrypt'] ) .then( function ( encryptionKey ) { }));
  62. 62. assert.promise( crypto.subtle.importKey( 'raw', keyBuf, { name: 'AES-CBC' }, true, ['encrypt', 'decrypt'] ) .then( function ( encryptionKey ) { return crypto.subtle.encrypt( aesCbc, encryptionKey, buf ) .then( function ( encryptResult ) { var encryptBuf = new Uint8Array( encryptResult ); var ciphertext = $.Uint8Util.toHexString( encryptBuf ); assert.equal( ciphertext, testVector.ciphertext ); }); }));
  63. 63. assert.promise( crypto.subtle.importKey( 'raw', keyBuf, { name: 'AES-CBC' }, true, ['encrypt', 'decrypt'] ) .then( function ( encryptionKey ) { return crypto.subtle.encrypt( aesCbc, encryptionKey, buf ) .then( function ( encryptResult ) { var encryptBuf = new Uint8Array( encryptResult ); var ciphertext = $.Uint8Util.toHexString( encryptBuf ); assert.equal( ciphertext, testVector.ciphertext ); return crypto.subtle.decrypt( aesCbc, encryptionKey, encryptBuf ) .then( function ( decryptResult ) { var plaintext = decoder.decode( new Uint8Array( decryptResult ) ); assert.equal( plaintext, testVector.plaintext ); }); }); }));
  64. 64. redux chained vs. nested promises
  65. 65. function importKey () { return crypto.subtle.importKey( 'raw', keyBuf, { name: 'AES-CBC' }, true, ['encrypt', 'decrypt'] ) } function encrypt ( importedKey ) { encryptionKey = importedKey; return crypto.subtle.encrypt( aesCbc, encryptionKey, buf ); } function decrypt ( encryptResult ) { var encryptBuf = new Uint8Array( encryptResult ); var ciphertext = $.Uint8Util.toHexString( encryptBuf ); assert.equal( ciphertext, testVector.ciphertext ); return crypto.subtle.decrypt( aesCbc, encryptionKey, encryptBuf ); }
  66. 66. function compare ( decryptResult ) { var plaintext = decoder.decode( new Uint8Array( decryptResult ) ); assert.equal( plaintext, testVector.plaintext ); } assert.promise( importKey() .then( encrypt ) .then( decrypt ) .then( compare ); );
  67. 67. Password-Based Key Derivation Functions (PBKDF) ● The randomness of cryptographic keys is essential for the security of cryptographic applications. SOURCE: SP 800-132
  68. 68. Password-Based Key Derivation Functions (PBKDF) ● The randomness of cryptographic keys is essential for the security of cryptographic applications. ● Most user-chosen passwords have low entropy and weak randomness properties. ○ shall not be used directly as cryptographic keys SOURCE: SP 800-132
  69. 69. Password-Based Key Derivation Functions (PBKDF) ● The randomness of cryptographic keys is essential for the security of cryptographic applications. ● Most user-chosen passwords have low entropy and weak randomness properties. ○ shall not be used directly as cryptographic keys ● KDFs are deterministic algorithms that are used to derive cryptographic keying material from a secret value, such as a password. SOURCE: SP 800-132
  70. 70. Salt A non-secret value that is used in a cryptographic process, usually to ensure that the results of computations for one instance cannot be reused by an Attacker. SOURCE: SP 800-63; CNSSI-4009
  71. 71. PBKDF Specification Input: P Password S Salt C Iteration count kLen Length of MK in bits; at most (232-1) x hLen Parameter: PRF HMAC with an approved hash function hlen Digest size of the hash function Output: mk Master key http://csrc.nist.gov/publications/nistpubs/800-132/nist-sp800-132.pdf
  72. 72. QUnit.test( 'PBKDF2', function ( assert ) { var testVector = { password : 'password', salt: 'cf7488cd1e48e84990f51b3f121e161318ba2098aa6c993ded1012c955d5a3e8', iterations: 100, key: 'c12b2e03a08f3f0d23f3c4429c248c275a728814053a093835e803bc8e695b4e' }; var alg = { name: 'PBKDF2', hash: 'SHA-1', salt: $.Uint8Util.fromHexString( testVector.salt ), iterations: testVector.iterations }; // import key, derive bits and compare });
  73. 73. var passwordBuf = decoder.decode( testVector.password ); assert.promise( crypto.subtle.importKey('raw', passwordBuf, 'PBKDF2', false, ['deriveKey']) .then(function ( keyResult ) { }));
  74. 74. var passwordBuf = decoder.decode( testVector.password ); assert.promise( crypto.subtle.importKey('raw', passwordBuf, 'PBKDF2', false, ['deriveKey']) .then(function ( keyResult ) { return crypto.subtle.deriveBits( alg, keyResult, 256 ) .then(function ( deriveResult ) { var deriveBuf = new Uint8Array( deriveResult ); var key = $.Uint8Util.toHexString( deriveBuf ); assert.equal( key, testVector.key ); }); }));
  75. 75. Data Flow and Storage (expected) ● Salt = initial random ● IV = initial random ● Ciphertext = AES( todos, Key, IV )
  76. 76. Data Flow and Storage (actual) ● PBKDF2 only implemented in Firefox 33 ● Substitute HMAC to generate 256 bit key ○ (do not try this at home)
  77. 77. Set and Confirm Password On first use, password must be established.
  78. 78. Password Entry Field <header id="header"> <h1><span>secure</span> todos</h1> <input id="new-todo" placeholder="What needs to be done?" class="hidden"> <input id="todo-password" type="password" placeholder="Enter Password" autofocus class="edit"> </header>
  79. 79. Render Password Entry Field render: function () { var todos, placeholder; if (this.todos) { this.$password.addClass('hidden'); // todos list rendering... } else { if (!cryptoStorage.initialized) { placeholder = (this.$password.data('confirm') ? 'Confirm Password' : 'Set Password'); this.$password.attr('placeholder', placeholder); } this.$password.removeClass('hidden').focus(); } }
  80. 80. Enter and Validate Password On subsequent uses, password must be entered to unlock todos. An invalid password will shake the password input field and outline in red.
  81. 81. CSS3 Shake Animation #todo-password.invalid { margin-left: 50px; padding: 3px 3px 3px 7px; border: 3px solid; width: 493px; border-radius: 6px; border-color: red; outline-color: red; animation: shake .5s linear; } @keyframes shake { 8%, 41% { transform: translateX(-10px); } 25%, 58% { transform: translateX(10px); } 75% { transform: translateX(-5px); } 92% { transform: translateX(5px); } 0%, 100% { transform: translateX(0); } }
  82. 82. Demo
  83. 83. validatePassword: function (password, confirmPassword) { var that = this; if (confirmPassword && confirmPassword != password) { return new Promise(function (resolve, reject) { reject(new Error('passwords do not match')); }); } return cryptoStorage.authenticate(password).then(function () { return util.store(); }).then(function (result) { that.todos = result; }) }
  84. 84. Convert store to return a Promise store: function (data) { if (data) { return cryptoStorage.setItem(data); } else { return cryptoStorage.getItem(); } }
  85. 85. Data Flow and Storage (API)
  86. 86. Random IV and Salt if ( !this.initialized ) { this.salt = new Uint8Array( 32 ); $.WebCryptoAPI.getRandomValues( this.salt ); this.hexSalt = $.Uint8Util.toHexString( this.salt ); this.iv = new Uint8Array( 16 ); $.WebCryptoAPI.getRandomValues( this.iv ); this.hexIV = $.Uint8Util.toHexString( this.iv ); this.initialized = true; }
  87. 87. Generate Key from Password return $.WebCryptoAPI.subtle.importKey('raw', this.salt, hmacSha256, true, ['sign', 'verify']) .then(function (keyResult) { });
  88. 88. Generate Key from Password return $.WebCryptoAPI.subtle.importKey('raw', this.salt, hmacSha256, true, ['sign', 'verify']) .then(function (keyResult) { return $.WebCryptoAPI.subtle.sign(hmacSha256, keyResult, buf) .then(function (signResult) { }); });
  89. 89. Generate Key from Password return $.WebCryptoAPI.subtle.importKey('raw', this.salt, hmacSha256, true, ['sign', 'verify']) .then(function (keyResult) { return $.WebCryptoAPI.subtle.sign(hmacSha256, keyResult, buf) .then(function (signResult) { var keyBuf = new Uint8Array(signResult); // importKey for later AES encryption return $.WebCryptoAPI.subtle.importKey('raw', keyBuf, {name: 'AES-CBC'}, true, ['encrypt', 'decrypt']) .then(function (result) { }); }); });
  90. 90. Generate Key from Password return $.WebCryptoAPI.subtle.importKey('raw', this.salt, hmacSha256, true, ['sign', 'verify']) .then(function (keyResult) { return $.WebCryptoAPI.subtle.sign(hmacSha256, keyResult, buf) .then(function (signResult) { var keyBuf = new Uint8Array(signResult); // importKey for later AES encryption return $.WebCryptoAPI.subtle.importKey('raw', keyBuf, {name: 'AES-CBC'}, true, ['encrypt', 'decrypt']) .then(function (result) { that.encryptionKey = result; if (!that.hasTodos) { return that.setItem([]); } }); }); });
  91. 91. Encrypt and Store var encoder = new TextEncoder(); var todosBuf = encoder.encode(JSON.stringify(value)); var aesCbc = {name: 'AES-CBC', iv: this.iv }; var data = { salt: this.hexSalt, iv: this.hexIV, ciphertext: null }; return $.WebCryptoAPI.subtle.encrypt(aesCbc, this.encryptionKey, todosBuf) .then(function (result) { data.ciphertext = $.Uint8Util.toHexString(new Uint8Array(result)); localStorage.setItem(NAMESPACE, JSON.stringify(data)); });
  92. 92. Decrypt var todosBuf = $.Uint8Util.fromHexString(data.ciphertext); var aesCbc = {name: 'AES-CBC', iv: this.iv }; $.WebCryptoAPI.subtle.decrypt(aesCbc, this.encryptionKey, todosBuf) .then(function (result) { var decoder = new TextDecoder(); var plaintext = decoder.decode(new Uint8Array(result)); try { data.todos = JSON.parse(plaintext); resolve(data.todos); } catch (err) { reject(err); } }, function (err) { reject(err); });
  93. 93. Encrypted in localStorage sqlite> select * from ItemTable; todos-jquery-webcryptoapi|{"salt":" 455ad2b6be02de86226c8c10fe32ebfc439b197f6b0a7918 94dab6f6920e22ff","iv":" 29b0b0092148e5fa849931c821627ea7","ciphertext":" b1770f7729edde3736eb4c26df6f4a56a236e01c525e157c f24ce76b35f8c622845a97f561c2c13942677db765e0638e f2ed90f191d5d57dcfc22fc7cd4c712716fc0e6e8748fb95 0430cb11a7e5c66ca4c55df4d88551d5b88666cd7fa4330c 85f20e88e30da752adf24ad71913bfb9"}
  94. 94. Questions? (and hopefully answers)

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