Let's Encrypt - Free SSL certificates for the masses Pete ...schd.ws/hosted_files/commons17/54/Lets encrypt Orlando_2017.pdfDSA (Digital Signature Algorithm) Elliptic Curve Cryptography

Let's Encrypt - Free SSL certificates for the masses

Pete HelgrenBible Study Fellowship International

San Antonio, TX

Agenda

Overview of data security

Encoding and Encryption

SSL and TLS

Certficate options

Self-signed

Commercial

Free

Installation

General

IBM i

Why use a certificate ?

Encoding

Encoding

The process of putting a sequence of characters into a special format for transmission or storage purposes.

Most common : BASE64 encoding, encoding binary data into ASCII characters.

Encoding is NOT encryption ! But is often used in conjunction with encryption.

Encryption

Recognize any of these schemes ?

Encryption

Encryption - SymmetricBoth parties share a ‘secret key’

Party A generates a ‘shared secret’ key and sends the key to party B.Party A uses the shared secret key to encrypt the data and send it to Party B. Party B uses their shared secret key to decrypt the data.Party B uses shared secret key to encrypt the data and send it to Party A. Party A uses the shared secret key to decrypt the data.

Encryption

Symmetric

Encryption

Encryption – Asymmetric

Both parties share ‘public’ keys so that each of them can decrypt the content sent by the other using their public keys.

Party A generates a private key and a public key and sends the public key to party B.Party B generates a private key and a public key and sends the public key to party A.Party A uses Party B’s public key to encrypt the data and send it to Party B. Party B uses their private key to decrypt the data.Party B uses Party A’s public key to encrypt the data and send it to Party A. Party A uses their private key to decrypt the data.

Encryption

Asymmetric

Encryption

Symmetric – doesn’t scale well.

Good for single, party-party data exchanges

Trust in the key and the server is up to you

If the key is compromised, you’re cooked.

Asymmetric – Can scale with 3rd party CA

Many to one and many to many

Key trust relegated to 3rd party CA

If server key compromised, you’re cooked

If CA is compromised, you’re cooked.

Encryption

Asymmetric key most common.

Certificate authority needed as 3rd party

x.509 Certificate is most widely used.

Contains identifying information such as Company name and maybe address

Contains the public key of the public/ private key pair (private key remains on server)

Issued by CA

Encryption

Ciphers (most common and accepted):

RSA (after the inventors Rivest, Shamir, and Adelman)

DSA (Digital Signature Algorithm)

Elliptic Curve Cryptography (ECC)

Diffie-Hellman (DH)and Elliptic Curve Diffie-Hellman (ECDH)

AES - Advanced Encryption Standard

Galois/Counter Mode (GCM)

Cipher “suites”

Related

Hashes – SHA256, SHA1, MD5

Deprecated

RC4 - Rivest Cipher 4

SHA1

Cipher “Suites”

A “suite” combines one or more ciphers

Authentication: RSA, DSA, ECDSA

Encryption:RC4, 3DES, AES

Message Authentication (MAC):HMAC-SHA256, HMAC-SHA1, HMAC-MD5

Key Exchange: RSA, Diffie-Hellman, ECDH, SRP, PSK

Cipher “Suites”

From my “SSL” config in Apache (Linux):

SSLCipherSuite "EECDH+ECDSA+AESGCM EECDH+aRSA+AESGCM EECDH+ECDSA+SHA384

EECDH+ECDSA+SHA256 EECDH+aRSA+SHA384 EECDH+aRSA+SHA256

EECDH EDH+aRSA !aNULL !eNULL !LOW !3DES !MD5 !EXP !PSK !SRP !DSS !RC4"

SSL vs TLS

These protocols establish the structure and steps of a secure connection

Basically: Old vs New

SSL (old) – Secure Sockets Layer

All versions have been deprecated

TLS (new) – Transport Security Layer protocol - Version 1.1 and 1.2 (1.3 on the way!)

TLS – Step by step

Three-way handshake for TCP

TLS -Client “Hello”

Client establishes connection with server

ClientHello: Provides a starting point forcommunication, and a set of options (Version,

CipherSuites, etc) for the receiving party (Server)to choose from regarding the connection.

TLS - Server “Hello”

Server responds to the connection request

The server picks the TLS protocol version for further communication, decides on a ciphersuite from the list provided by the client, attaches its certificate, and sends the response back to the

client. Optionally, the server can also send a

request for the client’s certificate and parameters for other TLS extensions.

Server “Hello”

ClientKeyExchange: Confirms the selectedencryption algorithm (RSA, Diffie-Hellman orFortezza/DMS)

Client change cipher

Client's ChangeCipherSpec: Indicates that the client is ready to begin secure communications. Finished: Indicates that further messages from the client will be encrypted

Server change cipher

Server's ChangeCipherSpec: Indicates that theserver is ready to begin secure communications.Finished: Indicates that further messages fromthe server will be encrypted.

Assuming both sides are able to negotiate a common version and cipher, and the client is happy with the certificate provided by the server, the client initiates either the RSA or the Diffie-Hellman key

exchange, which is used to establish the symmetric key for the ensuing session.

The server processes the key exchange parameters sent by the client, checks message integrity by verifying the MAC, and returns

an encrypted Finished message back to the client.

The client decrypts the message with the negotiated symmetric key, verifies the MAC, and if all is well, then the tunnel is established

and application data can now be sent.

MAC - message authentication code - one-way cryptographic hash function

Trusted 3rd party verification

In PKI it’s all about trust!

Trust a 3rd party CATrust the “self-signed” certificate (you are your own CA)

WHO do you trust?

Third party Certificate Authorities

Fee based

Comodo

GoDaddy

Verisign

Thawt

Globalsign

Symantec

3rd party CA’s

FREE!

Let’s Encrypt

Cloud Flare

SSL for Free (Let’s Encrypt ACME server)

Let’s Encrypt basics

Free!

Available in 90 day lifespans

Wildcards not supported

Multiple subdomains and domains on a single certificate is supported.

Automated renewal and revocation through ACME clients (most platforms..except IBM i for now)

Let’s Encrypt methods

Two ways to handle the request and installation:

Manually – there are step by step instructionsCertbot – about 95% automatedACME clients (Automated Certificate Management Environment)

Although some registrars and web services providers support Let’s Encrypt, many do not so you’ll end up “rolling your own”.

ACME clients

Certbot

Pre-built, wizard-like scripts.

Most steps completely automated.

Get just a cert or help with install on server.

Other “automated” scripts and websites in:

PerlPythonJavaJavascriptRubyPHP MANY others!

Certificate generation

Certificate signing request

Sent to your CA

Contains the public key

Java – Keytool

keytool -genkey -alias mydomain -keyalg RSA -keystore keystore.jks -keysize 2048keytool -certreq -alias mydomain -keystore keystore.jks -file mydomain.csr

Certificate generation

Certificate signing request

OpenSSL

openssl genrsa -out /path/to/www_server_com.key 2048openssl req -new -key /path/to/www_server_com.key -out /path/to/www_server_com.csr

Requirements

The Country Name is mandatory and takes a two-letter country code.

The State or Province Name field requires a full name – do not use an abbreviation.

The Locality Name field is for your city or town.

In the Organization Name field, add your company or organization.

Organizational Unit Name is an optional field for your department or section.

The Common Name field is used for the Fully Qualified Domain Name (FQDN) of the website this certificate will protect.

Email address is an optional field for this request.

The challenge password and optional company name fields are optional and can be skipped as well

CSR Output

-----BEGIN CERTIFICATE REQUEST-----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-----END CERTIFICATE REQUEST-----

Certificate request

If all is well, you are sent either a file or a link.

You may have an intermediate file or you may be requested to “bundle” them (copy them together).

Installation may be manual, semi-automatic or automated (a la Certbot)

Self signed Certificates

One extra step (no CA to send you a cert)

Generate the x.509 certificate:

openssl req -x509 -sha256 -days 365 -key private.key -in csr.csr -out certificate.crt

How many days duration should you set?

3-5 years is most common (5 years -1825 days)

On IBM i we use DCM

Digital Certificate Manager

CAN be a challenge to use and understandGenerate a CSR Import the x.509 certificate from third party (Let’s Encrypt in our case)

DCM – Where is it?

DCM landing page

Select a “store”

Choose *SYSTEM store

Create a CSR

Create a CSR

For Let’s Encrypt - Verisign or other...

Complete CSR Request

Make sure your host/domain here matches your certificate request

Click continue and generate CSR

Ignore this warning at your own peril!

Send the request to Let’s Encrypt

The ACME client can help here

LE will need to confirm you are who you say you are. Creating a private key that you register with them. Also by validating your site through file access or DNS entry (file is easier – called a challenge)

I have been using the Bash shell version of an ACME client called….acme.sh and a java version.

You can find more info on acme.sh here:

https://github.com/Neilpang/acme.sh

Install acme.sh

Choose a location ( ~ for home folder, ‘git’ for git...whatever)

Use the bash shell in your ssh session: bash <enter>

git clone https://github.com/Neilpang/acme.sh.git

cd ./acme.sh

./acme.sh --install –force

Exit and then sign back in

Run it!

We already have a CSR generated by the DCM...so...

acme.sh --signcsr --csr /path/to/mycsr.csr -w /path/to/webroot/

What to do with the certificate

Import the generated .pem file

Import the LE Certificate

Running the ACME client probably put your certificate into a folder in the IFS. Point your path there:

Voila!

How to I USE it?

Back to the HTTP Admin panel

Configure SSL for your Apache instance

Access the keystore

Select the certficate

Choose valid CA (or whole store)

Complete!

Apache Adjustments

The SSL configuration tweaks provided by the wizard:

Added ibm_ssl_module

You add/modify the port assignment

Modifications made to your virtual host

Virtual host changes

I have a reverse proxy so I:

Removed the virtual host modifications from “PETES”

Added the mods to my Virtual Host entries in the reverse proxy:

90 day renewal

Not automated for DCM/IBM i Apache (yet!)

Issue the renew option for your ACME client to run

Import the renewed certificate

Renew Certificate

Import renewed certificate

Same as when you imported the new cert – in the IFS

Use Calendar reminder every 75 days

Basic steps when using DCM:

Use DCM to generate CSR

Use ACME client to use csr to generate LE certificate

Use DCM to import generated certificate

Every 60-75 days, renew the certificate with LE and import into DCM

Thanks!

Happy Encrypting!

Pete [email protected]