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SECURING DATA IN TRANSITUsing TLS in Constrained Devices
Copyright 2015 wolfSSL Inc.1
Session Presenters
Copyright 2015 wolfSSL Inc.2
Chris ConlonwolfSSL Inc.
Jacob BarthelmehwolfSSL Inc.
What We’re Covering Today
1. Introduction and History of wolfSSL (5 min)
2. Overview of SSL/TLS, and Crypto (15 min)
3. TLS Enabling a Simple HTTP Client (10 min)
4. Emerging Ciphers and Algorithms (10 min)
5. Time-Permitting Q & A (5 min)
Copyright 2015 wolfSSL Inc.3
wolfSSL IncHistory, Introduction, and Products
4 Copyright 2015 wolfSSL Inc.
wolfSSL History
Copyright 2015 wolfSSL Inc.5
About wolfSSL
Founded: 2004
Locations: Bozeman, MTSeattle, WAPortland, OR
Our Focus: Open Source Embedded Security (Apps, Devices, IoT, and Cloud)
Copyright 2015 wolfSSL Inc.6
Products: - wolfSSL- wolfSSL FIPS- wolfCrypt- wolfSSH- wolfSCEP- wolfSSL Inspection- yaSSL
One Billion Endpoints!
Copyright 2015 wolfSSL Inc.7
Factory Automation
Automotive / Smart Car
Smart Grid
Cloud Services
Routers
Databases
Connected Home
SensorsBattlefield Communication
Smart Energy Machine-to-Machine
Games
Appliances
Internet of Things
Mobile / Smartphones
Strategic Partnerships
Copyright 2015 wolfSSL Inc.8
History and GoalsSSL / TLS
9 Copyright 2015 wolfSSL Inc.
SSL/TLS - History and Protocols
● SSL / TLS / DTLS versions
Copyright 2015 wolfSSL Inc.10
Notes:● SSL 2.0 is insecure● SSL = “Secure Sockets Layer”● TLS = “Transport Layer Security”● DTLS = “Datagram TLS”
SSL/TLS - Goals
● Enable secure CLIENT / SERVER communication
Privacy + Prevent eavesdroppingAuthentication + Prevent impersonationIntegrity + Prevent modification
Copyright 2015 wolfSSL Inc.11
SSL/TLS - Simplified Analogy
Copyright 2015 wolfSSL Inc.12
Goals:A. Talk to the desired personB. Talk privately (securely)
Alice Bob
? ?
SSL/TLS - Simplified Analogy
Copyright 2015 wolfSSL Inc.13
Goals:A. Talk to the desired personB. Talk privately (securely)
Alice Bob
SSL/TLS - Simplified Analogy
Copyright 2015 wolfSSL Inc.14
Goals:A. Talk to the desired personB. Talk privately (securely)
Alice Bob
SSL/TLS - Simplified Analogy
● Goals:
○ Talk to the desired peer■ X.509 certificates (RSA, ECC)
○ Talk privately (securely)■ Encryption, Integrity checks
Copyright 2015 wolfSSL Inc.15
MITM Attacks
● Man in the Middle Attacks● One of the most prominent attacks TLS tries to prevent
Copyright 2015 wolfSSL Inc.16
RFC and ProtocolsSSL / TLS
17 Copyright 2015 wolfSSL Inc.
TLS - Protocol Specs
● Protocol Specifications
○ RFC 6101: SSL 3.0○ RFC 2246: TLS 1.0○ RFC 4346: TLS 1.1○ RFC 5246: TLS 1.2○ “Draft”: TLS 1.3
Copyright 2015 wolfSSL Inc.18
TLS - Protocols and Location
Copyright 2015 wolfSSL Inc.19
TLS - Sub Protocols
Handshake Protocol
● Responsible for negotiating a session, includes:○ Session identifier○ Peer certificate○ Compression method○ Cipher spec○ Master secret○ “is resumable”
Copyright 2015 wolfSSL Inc.20
1234 (A)
(B)
TLS - Sub Protocols
Copyright 2015 wolfSSL Inc.21
1234 (A)
(B)
TLS - Sub Protocols
Change Cipher Spec Protocol
● Signals transitions in ciphering strategies● Sent by both client and server
● Notifies receiving party that subsequent records will be protected under newly negotiated CipherSpec and keys
Copyright 2015 wolfSSL Inc.22
1234 (A)
(B)
TLS - Sub Protocols
Alert Protocol
● Convey severity and description of alert● Either “warning” or “fatal”● Fatal results in immediate termination of
connection● Encrypted and compressed as per CipherSpec
Copyright 2015 wolfSSL Inc.23
1234 (A)
(B)
TLS - Sub Protocols
Record Protocol
● Layered protocol (Sending Side)○ Fragments input data into blocks○ (optionally) compresses data○ Applies MAC○ Encrypts○ Transmits the result
Copyright 2015 wolfSSL Inc.24
1234 (A)
(B)
TLS - Sub Protocols
Record Protocol
● Layered protocol (Receiving Side)○ Decrypts received data○ Verifies data (using MAC)○ Decompresses○ Reassembles○ Delivers result to higher level
Copyright 2015 wolfSSL Inc.25
1234 (A)
(B)
Cipher SuitesSSL / TLS
26 Copyright 2015 wolfSSL Inc.
Cipher Suites: Structure
● Combination of algorithms:
Hash Functions: MD5, SHA-1, SHA-256, ..Block and Stream Ciphers: AES, 3DES, ChaCha20, ...Public Key Algorithms: RSA, ECC, NTRU, ...
Copyright 2015 wolfSSL Inc.27
CIPHER SUITE
Cipher Suites: Structure
Protocol_keyexchange_WITH_bulkencryption_mode_messageauth
Copyright 2015 wolfSSL Inc.28
Examples:
SSL_RSA_WITH_DES_CBC_SHASSL_DHE_RSA_WITH_DES_CBC_SHATLS_RSA_WITH_AES_128_CBC_SHATLS_DHE_DSS_WITH_AES_128_CBC_SHATLS_DHE_RSA_WITH_AES_256_CBC_SHA
X.509 Certs and KeysSSL / TLS
29 Copyright 2015 wolfSSL Inc.
Making Sense of X.509
● X.509 is a standard for PKI (public key infrastructure)
● Some things specified by it include:○ Public key certificates○ Certificate revocation lists○ Certificate path validation algorithm (CA / cert chain structure)
● Structure is expressed in ASN.1 syntax
Copyright 2015 wolfSSL Inc.30
X.509v3 Certificates
Structure of X.509v3 certificate is as follows:
● Certificate○ Version○ Serial Number○ Algorithm ID○ Issuer○ Validity
■ Not Before■ Not After
○ Subject○ Subject Public Key Info
■ Public Key Algorithm■ Subject Public Key
○ Issuer Unique Identifier (optional)○ Subject Unique Identifier (optional)○ Extensions (optional)
■ …○ Certificate Signature Algorithm○ Certificate Signature
Copyright 2015 wolfSSL Inc.31
X.509v3 Certificates
● Filename Extensions○ .pem
■ “Privacy-enhanced Electronic Mail”■ Base64-encoded DER certificate
○ .der, .cer, .crt■ Binary DER form
● Others include○ .p7b, .p7c (PKCS#7) – standard for signing/encrypting data○ .p12 (PKCS#12) – bundle certs and private keys○ .pfx (predecessor to .p12)
Copyright 2015 wolfSSL Inc.32
-----BEGIN CERTIFICATE-----……-----END CERTIFICATE-----
Certificate Chain
● A list of certificates followed by one or more CA certificates, where:
○ The Issuer of each certificate matches the Subject of the next○ Each cert is signed by the private key of the following cert○ The last cert in the chain (although not sent in the SSL/TLS
handshake) is the “root CA”
Copyright 2015 wolfSSL Inc.33
Certificate Chain
Copyright 2015 wolfSSL Inc.34
SSL / TLS on DevicesSecuring a simple HTTP client with TLS
35 Copyright 2015 wolfSSL Inc.
wolfSSL Library
Features● C-language based SSL/TLS library● Standards up to TLS 1.2 and DTLS 1.2● Focused on size and speed optimization, progressive● Minimum footprint size of 20-100 kB● Minimum RAM usage: 1-36kB
● Web server integration (NGINX, Lighttpd, Mongoose, GoAhead)
● OpenSSL Compatibility Layer● Hardware Crypto Support● Suite-B Compatible, FIPS 140-2 (Level 1) in process● Dual Licensed (GPLv2 and Commercial)
Copyright 2015 wolfSSL Inc.36
wolfSSL + FRDM-K64FUsing wolfSSL in a Simple Embedded Client App
37 Copyright 2015 wolfSSL Inc.
wolfSSL + FRDM-K64F
● Why are we using FRDM-K64F?○ Simplicity, relevance
● Could as easily use any number of embedded platforms:○ Microchip PIC32MX/MZ○ STMicro STM32F2/F4/F7○ Freescale Kinetis, Coldfire○ ...
Copyright 2015 wolfSSL Inc.38
wolfSSL + FRDM-K64F
● wolfSSL is available for download from wolfssl.com:
● And also from GitHub:
Copyright 2015 wolfSSL Inc.39
wolfSSL + FRDM-K64F
● Or might already be in your IDE!
○ Keil MDK-ARM “Software Pack”
○ Microchip MPLAB Harmony
○ Freescale MQX-SSL
Copyright 2015 wolfSSL Inc.40
wolfSSL + FRDM-K64F
● wolfSSL has tight integration for Freescale platforms (among others)
○ FREESCALE_MQX - MQX operating system○ FREESCALE_MMCAU - mmCAU HW crypto○ FREESCALE_K70_RNGA - K70 HW RNG○ FREESCALE_K53_RNGB - K53 HW RNG
Copyright 2015 wolfSSL Inc.41
wolfSSL + FRDM-K64F
● This platform is being used currently for a new product!
Smart Door Lock Product
● Door Lock = Freescale FRDM-K64F● Home Gateway = Freescale i.MX6● Security = wolfSSL
Copyright 2015 wolfSSL Inc.42
wolfSSL + FRDM-K64F
● Drop wolfSSL into an Existing Project
Copyright 2015 wolfSSL Inc.43
wolfSSL + FRDM-K64F
● wolfSSL / wolfCrypt Code Structure
Copyright 2015 wolfSSL Inc.44
wolfSSL + FRDM-K64F
● Configuring the SSL/TLS library
○ Configuring wolfSSL (user_settings.h)○ Project Properties -> Compiler -> Preprocessor○ Add WOLFSSL_USER_SETTINGS
○ This file contains wolfSSL-specific configuration defines○ Based on wolfSSL’s main settings.h file
Copyright 2015 wolfSSL Inc.45
wolfSSL + FRDM-K64F
● Include wolfSSL header file in main.c
● Initialize wolfSSL library
● Optionally, enable debug output (also define DEBUG_WOLFSSL)
Copyright 2015 wolfSSL Inc.46
#include “wolfssl/ssl.h”
/* initialize wolfSSL library */wolfSSL_Init();
/* enable wolfSSL debug output */wolfSSL_Debugging_ON();
wolfSSL + FRDM-K64F
● Create wolfSSL context (ex: using TLS 1.2)
● Enable (or set) peer verification
● Load trusted root CA certificate, from DER-formatted buffer
Copyright 2015 wolfSSL Inc.47
WOLFSSL_CTX* ctx;ctx = wolfSSL_CTX_new(wolfTLSv1_2_client_method());
/* turn on peer verification, register verify callback */wolfSSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, myVerify);
int ret;ret = wolfSSL_CTX_load_verify_buffer(ctx, ca_cert_der_2048, sizeof(ca_cert_der_2048), SSL_FILETYPE_ASN1)
wolfSSL + FRDM-K64F
● After socket has been created and connect()’ed, create wolfSSL session:
● Pass established socket file descriptor to wolfSSL
● Initiate SSL/TLS connection, do handshake with peer
Copyright 2015 wolfSSL Inc.48
WOLFSSL* ssl;if ((ssl = wolfSSL_new(ctx)) == NULL) err_sys("wolfSSL_new failed");
wolfSSL_set_fd(ssl, sockfd);
ret = wolfSSL_connect(ssl); if (ret != SSL_SUCCESS) err_sys("wolfSSL_connect failed");
wolfSSL + FRDM-K64F
● Write data using:
● And read data using:
Copyright 2015 wolfSSL Inc.49
wolfSSL_write(ssl, msg, msgSz);
wolfSSL_read(ssl, reply, sizeof(reply));
wolfSSL + FRDM-K64F
● Shutdown SSL/TLS session
● Free resources:
Copyright 2015 wolfSSL Inc.50
wolfSSL_shutdown(ssl);
wolfSSL_free(ssl);wolfSSL_CTX_free(ctx);wolfSSL_Cleanup();
Peak RAM Usage
● RSA Cipher Suites
● ECC Cipher Suites
Copyright 2015 wolfSSL Inc.51
Math Library Key Size Peak Stack Use Peak Heap Use
fast 1024 10k 9k
fast 2048 13k 11k
normal 1024 6k 14k
normal 2048 7k 17k
Math Library Key Size Peak Stack Use Peak Heap Use
fast 256 7k 12k
normal 256 6k 15k
wolfSSL + FRDM-K64F
It’s as simple as that!(try it yourself and see)
Copyright 2015 wolfSSL Inc.52
Emerging CiphersWhat’s hot in the crypto world!
53 Copyright 2015 wolfSSL Inc.
Emerging Ciphers
● ChaCha20● Poly1305● Curve25519● Ed25519
Created by Daniel Bernstein a research professor at the University of Illinois, Chicago
Chacha20-Poly1305 AEAD used in Google over HTTPS
Ed25519 and ChaCha20-Poly1305 AEAD used in Apple’s HomeKit (iOS Security)
Copyright 2015 wolfSSL Inc.54
ChaCha20 Info
● Based from Salsa20 stream cipher using a different quarter-round process giving it more diffusion
● Fast stream cipher that also can have block characteristics● Can be used for AEAD encryption with Poly1305● Was published by Bernstein in 2008
Used by● Google Chrome● TinySSH● Apple HomeKit● wolfSSL
Copyright 2015 wolfSSL Inc.55reference 1
ChaCha20 Quarter Round
The heart of ChaCha20 is the quarter round. Operations performed are (note ^ means xor)
a += b; d ^= a; d <<<= 16; c += d; b ^= c; b <<<= 12; a += b; d ^= a; d <<<= 8; c += d; b ^= c; b <<<= 7;
Where a,b,c, and d are 32 bit unsigned integers.
Copyright 2015 wolfSSL Inc.56
ChaCha20 Matrix
Data for encryption is arranged into a matrix
constant(0) constant(1) constant(2) constant(3) key(4) key(5) key(6) key(7)key(8) key(9) key(10) key(11)input(12) input(13) input(14) input(15)
Copyright 2015 wolfSSL Inc.57
ChaCha20 Operation
To complete a double round 8 quarter rounds are performed. The first 4 quarter rounds consist of a column round. All data used from the matrix x is in similar columns. The last 4 quarter rounds consist of a diagonal round. All data used in the quarter round from the matrix x is in a diagonal pattern.
QUARTERROUND( x0, x4, x8,x12)QUARTERROUND( x1, x5, x9,x13)QUARTERROUND( x2, x6,x10,x14)QUARTERROUND( x3, x7,x11,x15)QUARTERROUND( x0, x5,x10,x15) QUARTERROUND( x1, x6,x11,x12)QUARTERROUND( x2, x7, x8,x13)QUARTERROUND( x3, x4, x9,x14)
Copyright 2015 wolfSSL Inc.58
0 1 2 34 5 6 78 9 10 1112 13 14 15
0 1 2 34 5 6 78 9 10 1112 13 14 15
ChaCha20 Performance
Copyright 2015 wolfSSL Inc.59
Poly1305 InfoWhy it’s used
Extremely fast in comparison to othersTo provide authentication of messages
Introduced by a presentation given from Bernstein in 2002
Naming scheme from using polynomial-evaluation MAC (Message Authentication Code) over a prime field Z/(2^130 - 5)
Copyright 2015 wolfSSL Inc.60reference 2
Poly1305 Performance
Copyright 2015 wolfSSL Inc.61
Poly1305 Outline Of Operation
Algorithm● Set an accumulator h to 0● Divide the message into chunks c● h = h + c and then h = rh, where r is part of the key● Periodically reduce h modulo 2^130 - 5● After all chunks ( c ) processed reduce h modulo 2^130 - 5● Add key to h
Copyright 2015 wolfSSL Inc.62
Curve25519
Used by● Tor● Google Chrome● Apple iOS● wolfSSL
Copyright 2015 wolfSSL Inc.63reference 3
Generic Montgomery curve. Reference 5
Curve25519 Visualization
Copyright 2015 wolfSSL Inc.64
Curve25519 Visualization
Copyright 2015 wolfSSL Inc.65
Curve25519 Performance
Copyright 2015 wolfSSL Inc.66
Curve25519 Performance
Copyright 2015 wolfSSL Inc.67
Ed25519
Used by● Tera Term● GnuPG● wolfSSL
Copyright 2015 wolfSSL Inc.68reference 4 Generic Twisted Edwards Curve. Reference 6
Ed25519 Terms● A is the public key point● a is the public key● H(*) is the Sha512 hash of *● B is the unique point (x, 4/5) ∈ E for which x is positive● M is the message● l is the prime 2^252 +
27742317777372353535851937790883648493
Copyright 2015 wolfSSL Inc.69
Ed25519 Sign / VerifySteps for signature1. computing r = H(hb, . . . , h2b−1, M)2. computing R = rB3. computing S = (r + H(R, A, M)a) mod l
VerificationSB = R + H(R, A, M)A
Copyright 2015 wolfSSL Inc.70
Ed25519 Sign
Copyright 2015 wolfSSL Inc.71
Ed25519 Verify
Copyright 2015 wolfSSL Inc.72
Ed25519 Fast Single VerifySB = R + H(R, A, M)A is changed to R = SB - H(R, A, M)A
Saving having to decompress R
Copyright 2015 wolfSSL Inc.73
Ed25519 Performance
Copyright 2015 wolfSSL Inc.74
Ed25519 Performance
Copyright 2015 wolfSSL Inc.75
References1. ChaCha20 http://cr.yp.to/chacha/chacha-20080128.pdf2. Poly1305 http://cr.yp.to/mac/poly1305-20050329.pdf3. Curve25519 http://cr.yp.to/ecdh/curve25519-20060209.pdf4. Ed25519 http://ed25519.cr.yp.to/ed25519-20110926.pdf
Generic Graph Images of Curves From5. "Montgomery curve1" by Krishnavedala - Own work. Licensed under
CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Montgomery_curve1.svg#/media/File:Montgomery_curve1.svg
6. "Twisted Edwards curve" by Krishnavedala - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Twisted_Edwards_curve.svg#/media/File:Twisted_Edwards_curve.svg
Copyright 2015 wolfSSL Inc.76
THANKS! QUESTIONS?
Copyright 2015 wolfSSL Inc.77
WOLFSSL
+1 (425) 245 - 8247
CHRIS CONLON
JACOB BARTHELMEH
Session Introduction
• Abstract• As designers and developers race to pack cool and eye catching features
into “Internet of Things” and connected devices, the security of those devices oftentimes takes a back seat. After all, how many times does a manufacturer hear end customers ask: “Is that refrigerator secured with TLS 1.2 or SSL 3.0?”. Security analysts and hackers aside, the answer is, hardly ever.
One of the most prominent ways of securing connected devices today is with TLS, or “Transport Layer Security”. This session will start with a basic introduction of TLS, working its way up to a demonstration of how easy it can be to integrate TLS into an existing Internet-connected device. Also included will be considerations on what ciphers, algorithms, and key sizes are preferential for various types of projects, touching on both the enterprise server side as well as the resource constrained device side. The open source wolfSSL SSL/TLS library will be used for demonstration purposes.
Copyright 2015 wolfSSL Inc.78
Session Introduction
• Key Takeaway
• Key takeaways from this session will include an overview of the TLS protocol, considerations when choosing what algorithms, ciphers and key sizes to use, and an understanding of how to add TLS to a new or existing application or device.
• Intended Audience
• The intended audience of this session is designers and engineers interested in using SSL/TLS to secure their projects or devices. Helpful prerequisites include a general understanding of C programming.
Copyright 2015 wolfSSL Inc.79