m Java Security Certificate Mgt
- jim mason
Key Points
- Java supports full security management - stores, certificates, keys in different key stores
References
Key Concepts
Certificate and PKI concepts
These instructions use the following terms:
- Key: A unique string of characters that seeds a mathematical algorithm for encryption and decryption. Keys come in pairs. A public key encrypts data to be decrypted with the corresponding private key.
- Certificate: A file that contains a public key and identifies who owns that key and its corresponding private key. In a signed certificate, a trusted certificate authority (CA) affirms that a public key does indeed belong to the owner named in the certificate. A certificate chain links a public key to a widely trusted root certificate.
- Keystore: A file that holds a combination of keys and certificates.
- PKCS, PFX: A binary format for key, certificate, and keystore files. Typical file names are *.pkcs, *.p12, *.p7b, *.pfx
- Java keystore: The binary format for keystores used by Code42 servers. Typical file names are .keystore and *.jks
- PEM: An ASCII text format for keys and certificates. Typical file extensions are *.pem, *.key, *.csr, *.cert. The binary counterpart is DER-format file. An X.509 certificate may or may not be in PEM format.
To identify a PEM file, read it with a console or text editor. If you see ASCII text, it's a PEM file.
Java Keytool Management
The Java keytool installs as part of a system's Java runtime engine (JRE) and runs at the Windows or Linux command line. To use keytool, install it on your system and configure its use as described below.
Windows keytool install
- Download and install a recent version of the JRE from Oracle.
- Locate the keytool with two commands.
The second command returns the location of keytool.exe.cd \
dir /b/s keytool.exe - Add the directory where keytool.exe resides to the PATH variable.
PATH=%PATH%;<directoryWhereKeytool.exeResides>
For example:PATH=%PATH%;C:\Program Files\Java\jre1.8.0_111\bin - Return to a directory that belongs to your user name:
cd \Users\<yourusername> - Repeat steps 2 and 3 for any terminal window in which you want to use the
keytoolcommand.
Linux keytool install
Install a recent version of the JRE with commands like the following:sudo apt-get update
sudo apt-get install default-jre
Create a keystore
Create a keystore using one of the following options:
- Option 1: Create a new key and Java keystore; import a CA's signature.
- Option 2: Package existing PEM-format keys and certificates in a new Java keystore.
- Option 3: Convert an existing PKCS or PFX keystore to a Java keystore.
Option 1: Create a new key and Java keystore; import a CA's signature
Step 1: Create a keystore and a signing request
Create a Java keystore and a request for a CA to sign your public key.
For help writing these commands, see DigiCert's Java Keytool CSR Wizard.
- Create the keystore with the command below, after substituting your value for one variable:
- <your.domain.com>: the complete domain name of your Code42 server.
The command will prompt you for two passwords. Supply the same value for both of them:
Enter keystore password:
Enter key password:keytool -genkeypair -alias <your.domain.com> -storetype jks -keystore <your.domain.com>.jks -validity 366 -keyalg RSA -keysize 4096
- The command prompts you for identifying data.
At "What is your first and last name" you must supply the domain name of the Code42 server you want to secure.
Most CAs require values for the other fields as well.
What is your first and last name? <your.domain.com> What is the name of your organizational unit? yourunit What is the name of your organization? yourorg What is the name of your City or Locality? yourcity What is the name of your State or Province? yourstate What is the two-letter country code for this unit? US
- Create the certificate signing request (CSR) with the command below, after substituting your value for all four occurrences of one variable:
- <your.domain.com>: the complete domain name of your Code42 server.
keytool -certreq -alias <your.domain.com> -file <your.domain.com>.csr
-keystore <your.domain.com>.jks -ext san=dns:<your.domain.com>
Step 2: Request a CA-signed certificate
- In the directory where you ran Step 1 above, find the file <your.domain.com>.csr
- Submit the file <your.domain.com>.csr to your CA.
- Details vary from one CA to another. Typically, you submit your request via a website, then the CA contacts you to verify your identity.
- CAs can send signed reply files in a variety of formats, and CAs use a variety of names for those formats. You want the CA's reply in PEM or PKCS#7 format.
- Wait (usually days or a week) for the CA's reply.
Step 3: Import the CA's reply
The CA's reply will provide one PKCS file or multiple PEM files. Import them into your keystore as follows:
- Copy the CA's files into the directory where you created the keystore in Step 1 above.
- Windows only: Configure the Keytool Command as described above.
- Use
keytoolto import the CA reply files to your keystore
(The commands will prompt you for your keystore password):
- If the CA sent a PKCS file, use the command below, after substituting your values for two variables:
- <your.domain.com> : The complete domain name of your Code42 server.
- <CAreply.pkcs> : The name of the PKCS file provided by the CA.
keytool -importcert -alias <your.domain.com> -file <CAreply.pkcs> -keystore <your.domain.com>.jks -trustcacerts
- If the CA sent PEM files, there may be one file, but most often there are two or three. Import the files to your keystore with commands in the order shown below, after substituting your values for four variables:
- <root.cert.pem> : The name of the root certificate file
- <intermediate.cert.pem> : The name of the intermediate certificate file
The root and intermediate files link the CA's signature to a widely trusted root certificate that is known to web browsers. Most, but not all, CA replies include roots and intermediates. - <your.domain.com> : The complete domain name of your Code42 server
- <server.cert.pem> : The name of the server certificate file
The file links your domain name with your public key and the CA's signature.
keytool -importcert -alias root -file <root.cert.pem> -keystore <your.domain.com>.jks -trustcacerts keytool -importcert -alias intermediate -file <intermediate.cert.pem> -keystore <your.domain.com>.jks -trustcacerts keytool -importcert -alias intermediat2 -file <intermediat2.cert.pem> -keystore <your.domain.com>.jks -trustcacerts keytool -importcert -alias <your.domain.com> -file <server.cert.pem> -keystore <your.domain.com>.jks -trustcacerts
If you import certificates in the wrong order, the above commands return an error message. To resolve the error, you can:
- Consult your CA.
- Re-arrange the order of certificates and try again.
- Read each certificate with the following command:
keytool -printcert -file <filename.cert.pem>
In the output, note the Owner and Issuer (signer) of each certificate. Order your import commands so that the Issuer of each certificate matches the Owner in the previous command.
- Proceed to configuring your Code42 server below.
Option 2: Package existing PEM-format key and certificates in a new Java keystore
If you have an existing private key and certificates for your Code42 server's domain, in PEM format, importing them into a Java keystore requires the OpenSSL tool. OpenSSL can package the PEM files in a PKCS keystore. Java keytool can then convert the PKCS keystore to a Java keystore.
- Install OpenSSL:
- Windows: Download and install OpenSSL.
- Linux: Verify that OpenSSL is installed by issuing the command
openssl version
If that returns an error, install OpenSSL with a command likesudo apt-get install openssl
- Gather your private key, server certificate, and intermediate certificate into one directory.
- Package the key and certificates into a PKCS keystore with the command below, after substituting your values for four variables
(The command will prompt you for your keystore password):- <server.cert.pem>: The name of the server certificate file
The file links your domain name with your public key and CA's signature. - <private.key.pem>: The private counterpart to the public key in <server.cert.pem>
- <intermediate.cert.pem>: The name of the intermediate certificate file
The file links the CA's signature to a widely trusted root certificate that is known to web browsers. - <your.domain.com> : The complete domain name of your Code42 server
- <server.cert.pem>: The name of the server certificate file
openssl pkcs12 -export -in <server.cert.pem> -inkey <private.key.pem> -certfile <intermediate.cert.pem> -name "<your.domain.com>" -out <your.domain.com>.p12
- Convert the resulting PKCS keystore file, <your.domain.com>.p12 into a Java keystore. See Option 3, below.
Option 3: Convert an existing PKCS or PFX keystore to a Java keystore
If you have an existing PKCS or PFX keystore for your Code42 server's domain, convert it to a Java keystore.
- Windows only: Configure the keytool command as described above.
- Issue the command below, after substituting your values for two variables
(The command will prompt you for keystore passwords):- <your.domain.com.p12> : The existing keystore file.
- <your.domain.com> : The complete domain name of your Code42 server
keytool -importkeystore -srckeystore <your.domain.com.p12> -srcstoretype PKCS12 -destkeystore <your.domain.com>.jks -deststoretype jks
- Proceed to configuring your Code42 server below.
Configure your server to use your keystore
Step 1: Back up your Code42 server's database
As a best practice, back up your Code42 server's database:
- Open the administration console.
- Navigate to Settings > Server.
- From the action menu, select Dump Database.
Step 2: Import your keystore to your Code42 server
- In the administration console, select Settings > Security > Keys.
- At SSL, check Require SSL to access console.
- Click Import Keystore.
- Select your Java keytore file, <your.domain.com>.jks, and provide
<yourpassword>. - Return to the system command line and stop and restart the Code42 server:
Certificate Use Cases
Client and Server SSL encryption of messages using PKI concept
- Client and server each have their own private key and matching public key
- Client and server exchange public keys as certificates
- For each message sent, the source system encrypts the message with the private key
- For each message received, the receiver uses the public key to decrypt the message
Server setup for PKI certificates approved by a CA
- Typically a server is setup by a Certificate Authority administrator in a very secure environment.
- The CA is often an intermediate CA with a trust chain back to a root CA ( Verisign, Thawte or other root CA )
- Certificate files will often use a user, domain name or server name depending on planned usage
- Private keys are generated and usually well protected in a secure key store.
- A CSR ( Certificate Signing Request ) is generated for root CA authentication ( vs self signed certs )
- the server CA reviews and approves the CSR providing a complete trust chain to a root CA
- The public key is generated from the private key as a certificate PEM file normally.
- If needed, a PKCS12 file can be generated from the private key as a format to send the certificate to the client
Client setup for PKI certificates
Key management and distribution concepts
private keys can have a pass phrase to protect access
better use an encrypted wrapper with a password for key distribution via sftp or secure email
Document signing with the Private key
Use Java JCA to sign documents
java-security-sign-documents-JCA-baeldung.com-Digital Signatures in Java.pdf
In this tutorial, we're going to learn about the Digital Signature mechanism and how we can implement it using the Java Cryptography Architecture (JCA). We'll explore the KeyPair, MessageDigest, Cipher, KeyStore, Certificate, and Signature JCA APIs.
We'll start by understanding what is Digital Signature, how to generate a key pair, and how to certify the public key from a certificate authority (CA). After that, we'll see how to implement Digital Signature using the low-level and high-level JCA APIs.
Digital Signature
Digital Signature is a technique for ensuring:
- Integrity: the message hasn't been altered in transit
- Authenticity: the author of the message is really who they claim to be
- Non-repudiation: the author of the message can't later deny that they were the source
Send message with digital signature
Technically speaking, a digital signature is the encrypted hash (digest, checksum) of a message. That means we generate a hash from a message and encrypt it with a private key according to a chosen algorithm.
The message, the encrypted hash, the corresponding public key, and the algorithm are all then sent. This is classified as a message with its digital signature.
Digital Certificate and Public Key
A certificate is a document that associates an identity to a given public key. Certificates are signed by a third-party entity called a Certificate Authority (CA).
We know that if the hash we decrypt with the published public key matches the actual hash, then the message is signed. However, how do we know that the public key really came from the right entity? This is solved by the use of digital certificates.
A Digital Certificate contains a public key and is itself signed by another entity. A chain of trust.
The most top-level entity is self-signed, which means that his public key is signed by his own private key.
Load a private key from a keystore
Using the KeyStore API, and the previous Keystore file, sender_keystore.p12, we can get a PrivateKey object:
KeyStore keyStore = KeyStore.getInstance("PKCS12");
keyStore.load(new FileInputStream("sender_keystore.p12"), "changeit");
PrivateKey privateKey =
(PrivateKey) keyStore.getKey("senderKeyPair", "changeit");If CA needs to sign the certificate first
if we're going to work with a CA-signed certificate, then we need to create a certificate signing request (CSR). We do this with the certreq command:
keytool -certreq -alias senderKeyPair -storetype PKCS12 \
-keystore sender_keystore.p12 -file -rfc \
-storepass changeit > sender_certificate.csr
The CSR file, sender_certificate.csr, is then sent to a Certificate Authority for the purpose of signing. When this is done, we'll receive a signed public key wrapped in an X.509 certificate, either in binary (DER) or text (PEM) format. Here, we've used the rfc option for a PEM format.
Create personal certificate for shared SSL
use a personal name or identity or a proxy name
Setup a Web Server with SSL
Java Keystore Types
https://www.pixelstech.net/article/1408345768-Different-types-of-keystore-in-Java----Overview
Keystore is a storage facility to store cryptographic keys and certificates. They are most frequently used in SSL communications to prove the identity of servers and clients. A keystore can be a file or a hardware device. Three are three kinds of entries can be stored in a keystore depending on the types of keystores.
The three types of entries are:
PrivateKey : This is a type of keys which are used in asymmetric cryptography. It is usually protected with password because of its sensitivity. It can also be used to sign a digital signature.
Certificate : A certificate contains a public key which can identify the subject claimed in the certificate. It is usually used to verify the identity of a server. Sometimes it is also used to identify a client when requested.
SecretKey : A key entry which is used in symmetric cryptography.
Depending on what entries the keystore can store and how the keystore can store the entries, there are a few different types of keystores in Java: JKS, JCEKS, PKCS12, PKCS11 and DKS. You can find the introduction of these keystore on Oracle's Java Cryptography Architecture description.
Next, we will have an overview of these keystore types.
JKS, Java Key Store. You can find this file at sun.security.provider.JavaKeyStore. This keystore is Java specific, it usually has an extension of jks. This type of keystore can contain private keys and certificates, but it cannot be used to store secret keys. Since it's a Java specific keystore, so it cannot be used in other programming languages. The private keys stored in JKS cannot be extracted in Java.
JCEKS, JCE key store(Java Cryptography Extension KeyStore). It is a super set of JKS with more algorithms supported. It is an enhanced standard added later by Sun. You can find this file at com.sun.crypto.provider.JceKeyStore. This keystore has an extension of jceks. The entries which can be put in the JCEKS keystore are private keys, secret keys and certificates. This keystore provides much stronger protection for stored private keys by using Triple DES encryption.
The provider of JCEKS is SunJCE, it was introduced in Java 1.4. Hence prior to Java 1.4, only JKS can be used.
PKCS12, this is a standard keystore type which can be used in Java and other languages. You can find this keystore implementation at sun.security.pkcs12.PKCS12KeyStore. It usually has an extension of p12 or pfx. You can store private keys, secret keys and certificates on this type. Unlike JKS, the private keys on PKCS12 keystore can be extracted in Java. This type is portable and can be operated with other libraries written in other languages such as C, C++ or C#.
The pkcs12 command allows PKCS#12 files (sometimes referred to as PFX files) to be created and parsed. PKCS#12 files are used by several programs including Netscape, MSIE and MS Outlook.
Currently the default keystore type in Java is JKS, i.e the keystore format will be JKS if you don't specify the -storetype while creating keystore with keytool. However, the default keystore type will be changed to PKCS12 in Java 9 because its enhanced compatibility compared to JKS. You can check the default keystore type at $JRE/lib/security/java.security file:
PKCS11, this is a hardware keystore type. It provides an interface for the Java library to connect with hardware keystore devices such as SafeNet's Luna, nCipher or Smart cards. You can find this implementation at sun.security.pkcs11.P11KeyStore. When you load the keystore, you no need to create a specific provider with specific configuration. This keystore can store private keys, secret keys and certificates. When loading the keystore, the entries will be retrieved from the keystore and then converted into software entries.
DKS, Domain KeyStore is a keystore of keystore. It abstracts a collection of keystores that are presented as a single logical keystore. Itself is actually not a keystore. This new keystore type is introduced in Java 8. There is a new class DomainLoadStoreParameter which closely relates to DKS.
This keystore is located at sun.security.provider.DomainKeyStore.java.
Windows-MY, this is a type of keystore on Windows which is managed by the Windows operating system. It stores the user private keys and certificates which can be used to perform cryptographic operations such as signature verification, data encryption etc. Since it's a kind of native keystore, Java doesn't have a general API to access it. Oracle provides a separate API to access the Windows-MY keystore -- SunMSCAPI. The provider class for this API is sun.security.mscapi.SunMSCAPI.
BKS, BoucyCastle keystore, is a keystore format provided the popular third party Java cryptographic library provider -- BouncyCastle. It is a keystore similar to the JKS provided by Oracle JDK. But it supports storing secret key, private key and certificate. It is frequently used in mobile application developments.
In Java, there are a few choices on how a keystore can be processed. Writing the Java code is apparently a choice. Apart from this, a tool comes along with the JDK can also be used, it is called keytool.
keytool is a command line tool. It can be used to create keystore, generate keys, import and export certificates etc. For a full list of commands keytool supports, you can refer to Oracle keytool guideline.
If you are using IBM JDK, there is one more tool which can be used, it is ikeyman. ikeyman is a GUI tool which can provide a straightforward view of the keystore. The entries in the keystore. Keys and certificates can be created using ikeyman as well. It is a tool used frequently by system administrators.
Below are the details of each keystore supported in Java.
- Different types of keystore in Java -- JKS
- Different types of keystore in Java -- JCEKS
- Different types of keystore in Java -- PKCS12
- Different types of keystore in Java -- PKCS11
- Different types of keystore in Java -- DKS
- Different types of keystore in Java -- Windows-MY
- Different types of keystore in Java -- BKS
Certificate administration options
Java keytool
https://docs.oracle.com/javase/9/tools/keytool.htm#JSWOR-GUID-5990A2E4-78E3-47B7-AE75-6D1826259549
Openssl command line on any platform
Free CA admin tools including Fabric
Task - Add SSL cert into Java keystore jks and cacerts file from download
https://better-coding.com/how-to-add-ssl-certificate-into-java-cacerts-file-and-jks-keystore/
This simple guide shows how to download a certificate and how to add it into Java trust store.
1. Downloading certificate
You can download the certificate in a few ways. Using openssl tool or using browser
1.1. Download SSL certificate using openssl
- openssl s_client -showcerts -connect better-coding.com:443 /dev/null|openssl x509 -outform PEM >mycertfile.pem
1.2 Downloading SSL certificate using browser
You can download the certificate using Chrome by going to certificate details and then clicking “Copy to file” button.
2.1 Importing certificate into cacert
Go to the JAVA_HOME\bin directory and run:
- keytool -importcert -file mycertfile.pem -keystore cacerts -alias "Alias"
2.2 Importing certificate into jks keystore
- keytool -importcert -file mycertfile.pem -keystore keystore.jks -alias "Alias" -storepass <PASSWORD>
Openssl certficate adminisration
Use Linux default openssl if possible
includes default trust store for certificates
Openssl on Windows
install a valid Openssl binary from
Compile Openssl for Windows or get a binary package
only if needed ( usually on Windows if a binary not available )
add a trust store
Use or Create a Trust Store
either use system trust store or get Mozilla trust store
Windows Certificates Trust Store via mmc
Mozilla Root Certificate trust store text file
https://hg.mozilla.org/mozilla-central/raw-file/tip/security/nss/lib/ckfw/builtins/certdata.txt
Download & Install Windows Openssl binary
https://slproweb.com/products/Win32OpenSSL.html
For Windows, create openssl_start.bat
sets up openssl environment in Windows
WARNING: can't open config file: /usr/local/ssl/openssl.cnf
This can be solved as following:
- Close OpenSSL.
- Open a Command Prompt (CMD) as Administrator
- Run the following command:
SET OPENSSL_CONF=<<my openssl bin path>>\openssl.cnf
Create Keystore, Admin key, User key & cert
use pkcs12 keystore
all key types and portable to any language
Generate a private key for the admin
if using a protected passfile, store in protected zip w option name + dddd
D:\dsfw\files\keyhome>
openssl genrsa -aes256 -passout file:passfile.txt -out jemason1.key 2048
Generating RSA private key, 2048 bit long modulus
..............+++++
.........................................................................................................+++++
e is 65537 (0x010001)
The password file ideally is in UTF-8 encoding for openssl
type or cat the key file to see the encrypted text for the private key generated
type jemason1-pub.pem | more
-----BEGIN PUBLIC KEY-----
.... << more >> ...
-----END PUBLIC KEY-----
create the public key from the private key file
openssl rsa -in jemason1.key -out jemason1-pub.key -pubout
key files output:
jemason1-pub.key jemason1.key passfile.txt
OpenSSL on Linux
error - unknown option on openssl command - can't copy dashes
Search Results
Web results
openssl keeps giving me "unknown option" errors - Server Fault
https://serverfault.com › questions › openssl-keeps-giving-me-unknown-o...
2 answers
Aug 13, 2011 - Delete all of your dashes and re-type them on the command line. when you wish to copy and paste! the - in the out so use arrows to get there and remove - and then type - and press enter, the - near the out is the only - you need to delete and type then it works :D.
CSR - Certificate Signing Request
Get details from the site admin for OU, Cname, email, challenge password etc first
openssl req -new -key fd.key -out fd.cs
Create a pkcs12 file store for certificates
PKCS 12. In cryptography, PKCS #12 defines an archive file format for storing many cryptography objects as a single file. It is commonly used to bundle a private key with its X.509 certificate or to bundle all the members of a chain of trust. ... The filename extension for PKCS #12 files is .p12 or .pfx .
The PKCS#12 or PFX format is a binary format for storing the server certificate, intermediate certificates, and the private key in one encryptable file. PFX files usually have extensions such as .pfx and .p12. PFX files are typically used on Windows machines to import and export certificates and private keys
https://www.openssl.org/docs/man1.1.1/man1/openssl-pkcs12.html
For PKCS#12 file parsing only -in and -out need to be used for PKCS#12 file creation -export and -name are also used.
Controlling order of keys in pkcs12 file
If none of the -clcerts, -cacerts or -nocerts options are present then all certificates will be output in the order they appear in the input PKCS#12 files. There is no guarantee that the first certificate present is the one corresponding to the private key. Certain software which requires a private key and certificate and assumes the first certificate in the file is the one corresponding to the private key: this may not always be the case. Using the -clcerts option will solve this problem by only outputting the certificate corresponding to the private key. If the CA certificates are required then they can be output to a separate file using the -nokeys -cacerts options to just output CA certificates.
creates a pkcs12 file from a public key
openssl pkcs12 -export -in jemason1-pub.key -out jemason1.p12 -name "jmason Certificate"
jemfebapr
Tutorial - Create SSL certificates with OpenSSL
https://phoenixnap.com/kb/openssl-tutorial-ssl-certificates-private-keys-csrs
On Ubuntu
ssl folder /usr/lib/ssl is a link to
/etc/ssl
which contains /certs openssl.cnf /private
openssl.cnf has default values for a CSR otherwise they must be entered on CLI
openssl req –out certificatesigningrequest.csr -new -newkey rsa:2048 -nodes -keyout privatekey.keycreate the new key and csr request
openssl req –out jmason1.csr -new -newkey rsa:2048 -nodes -keyout jmason1.key
read the key
openssl req -in jmason1.csr -noout -text
Create a public key as a PEM file from private key
openssl rsa -in jmason1.key -outform PEM -pubout -out jmason1-pub.PEM
Create a PKCS12 format file that can be imported into a Windows keystore
Create self-signed certificate with openssl req
openssl-req, req - PKCS#10 certificate request and certificate generating utility
The req command primarily creates and processes certificate requests in PKCS#10 format. It can additionally create self signed certificates for use as root CAs for example.
openssl-x509, x509 - Certificate display and signing utility
https://www.openssl.org/docs/man1.1.1/
example 1 - create new self-signed root CA certificate, private and public key files and a password file
openssl req -x509 -sha256 -outform PEM -days 1000 -out jmason2-crt.pem -new -newkey rsa:2048 -nodes
-keyout jmason2-key.pem -passin file:passfile.txt
Generating a RSA private key
...........................................................+++++
.....................................................................................+++++
writing new private key to 'jmason2-key.pem'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [US]:US
State or Province Name (full name) [MA]:MA
Locality Name (eg, city) []:North Attleboro
Organization Name (eg, company) [Internet Widgits Pty Ltd]:Paramount Software Solutions
Organizational Unit Name (eg, section) []:software
Common Name (e.g. server FQDN or YOUR name) []:Jim Mason
Email Address []:.
openssl req options
-outform DER|PEM
This specifies the output format, the options have the same meaning and default as the -inform option.
-in filename
This specifies the input filename to read a request from or standard input if this option is not specified. A request is only read if the creation options (-new and -newkey) are not specified.
-x509
This option outputs a self signed certificate instead of a certificate request. This is typically used to generate a test certificate or a self signed root CA. The extensions added to the certificate (if any) are specified in the configuration file. Unless specified using the set_serial option, a large random number will be used for the serial number.
If existing request is specified with the -in option, it is converted to the self signed certificate otherwise new request is created.
Openssl simple CA app to sign requests
https://www.openssl.org/docs/man1.1.0/man1/ca.html
Potential Value Opportunities
Potential Challenges
Java app accesses web site with invalid certificate
https://www.infopackets.com/news/10023/how-fix-java-expired-or-not-yet-valid-certificate-error
whenever I try to access my work's website (which uses a Java applet), I receive an error message that says: 'Your security settings have blocked an application with an expired or not-yet-valid certificate from running.' I cannot proceed past that, and am therefore unable to access the website
Analysis steps
By clicking on the padlock with the (!) warning, the browser reported "Connection not secure"; I then clicked to view "More information" and then on the "View certificate" page, I could clearly see that the HTTPS certificate had in fact expired some time last year. This was the reason that the Java applet was reporting an error and would not proceed.
For Google Chrome try
Edit Settings > Privacy & Security > Web site exceptions > not secure connection = allow
How to Fix Java Expired or not-yet-valid Certificate Error.pdf
Candidate Solutions
Step-by-step guide for Example
sample code block