[java] How to properly import a selfsigned certificate into Java keystore that is available to all Java applications by default?

I do want to import a self signed certificate into Java so any Java application that will try to establish a SSL connection will trust this certificate.

So far, I managed to import it in

keytool -import -trustcacerts -noprompt -storepass changeit -alias $REMHOST -file $REMHOST.pem
keytool -import -trustcacerts -noprompt -keystore cacerts -storepass changeit -alias $REMHOST -file $REMHOST.pem

Still, when I try to run HTTPSClient.class I still get:

javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

    D:\Java\jdk1.5.0_10\bin\keytool -import -file "D:\Certificates\SDS services\Dev\dev-sdsservices-was8.infavig.com.cer" -keystore "D:\Java\jdk1.5.0_10\jre\lib\security\cacerts" -alias "sds certificate"

fist get the certificate from the provider
create a file ends wirth .cer and pase the certificate

copy the text file or  past   it  somewhere you can access it 
then use the cmd prompt as an admin and cd to the bin of the jdk,
the cammand that will be used is the:  keytool 

change the  password of the keystore with :

keytool  -storepasswd -keystore "path of the key store from c\ and down"

the password is : changeit 
 then you will be asked to enter the new password twice 

then type the following :

keytool -importcert -file  "C:\Program Files\Java\jdk-13.0.2\lib\security\certificateFile.cer"   -alias chooseAname -keystore  "C:\Program Files\Java\jdk-13.0.2\lib\security\cacerts"

I ended up writing a small script that adds the certificates to the keystores, so it is much easier to use.

You can get the latest version from https://github.com/ssbarnea/keytool-trust

#!/bin/bash
# version 1.0
# https://github.com/ssbarnea/keytool-trust
REMHOST=$1
REMPORT=${2:-443}

KEYSTORE_PASS=changeit
KEYTOOL="sudo keytool"

# /etc/java-6-sun/security/cacerts

for CACERTS in  /usr/lib/jvm/java-8-oracle/jre/lib/security/cacerts \
    /usr/lib/jvm/java-7-oracle/jre/lib/security/cacerts \
    "/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/lib/security/cacerts" \
    "/Applications/Xcode.app/Contents/Applications/Application Loader.app/Contents/MacOS/itms/java/lib/security/cacerts"
do

if [ -e "$CACERTS" ]
then
    echo --- Adding certs to $CACERTS

# FYI: the default keystore is located in ~/.keystore

if [ -z "$REMHOST" ]
    then
    echo "ERROR: Please specify the server name to import the certificatin from, eventually followed by the port number, if other than 443."
    exit 1
    fi

set -e

rm -f $REMHOST:$REMPORT.pem

if openssl s_client -connect $REMHOST:$REMPORT 1>/tmp/keytool_stdout 2>/tmp/output </dev/null
        then
        :
        else
        cat /tmp/keytool_stdout
        cat /tmp/output
        exit 1
        fi

if sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' </tmp/keytool_stdout > /tmp/$REMHOST:$REMPORT.pem
        then
        :
        else
        echo "ERROR: Unable to extract the certificate from $REMHOST:$REMPORT ($?)"
        cat /tmp/output
        fi

if $KEYTOOL -list -storepass ${KEYSTORE_PASS} -alias $REMHOST:$REMPORT >/dev/null
    then
    echo "Key of $REMHOST already found, skipping it."
    else
    $KEYTOOL -import -trustcacerts -noprompt -storepass ${KEYSTORE_PASS} -alias $REMHOST:$REMPORT -file /tmp/$REMHOST:$REMPORT.pem
    fi

if $KEYTOOL -list -storepass ${KEYSTORE_PASS} -alias $REMHOST:$REMPORT -keystore "$CACERTS" >/dev/null
    then
    echo "Key of $REMHOST already found in cacerts, skipping it."
    else
    $KEYTOOL -import -trustcacerts -noprompt -keystore "$CACERTS" -storepass ${KEYSTORE_PASS} -alias $REMHOST:$REMPORT -file /tmp/$REMHOST:$REMPORT.pem
    fi

fi

done

```

This worked for me. :)

sudo keytool -importcert -file filename.cer -alias randomaliasname -keystore $JAVA_HOME/jre/lib/security/cacerts -storepass changeit 

On Windows the easiest way is to use the program portecle.

1. Download and install portecle.
2. First make 100% sure you know which JRE or JDK is being used to run your program. On a 64 bit Windows 7 there could be quite a few JREs. Process Explorer can help you with this or you can use: System.out.println(System.getProperty("java.home"));
3. Copy the file JAVA_HOME\lib\security\cacerts to another folder.
4. In Portecle click File > Open Keystore File
5. Select the cacerts file
6. Enter this password: changeit
7. Click Tools > Import Trusted Certificate
8. Browse for the file mycertificate.pem
9. Click Import
10. Click OK for the warning about the trust path.
11. Click OK when it displays the details about the certificate.
12. Click Yes to accept the certificate as trusted.
13. When it asks for an alias click OK and click OK again when it says it has imported the certificate.
14. Click save. Don’t forget this or the change is discarded.
15. Copy the file cacerts back where you found it.

On Linux:

You can download the SSL certificate from a web server that is already using it like this:

$ echo -n | openssl s_client -connect www.example.com:443 | \
   sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > /tmp/examplecert.crt

Optionally verify the certificate information:

$ openssl x509 -in /tmp/examplecert.crt -text

Import the certificate into the Java cacerts keystore:

$ keytool -import -trustcacerts -keystore /opt/java/jre/lib/security/cacerts \
   -storepass changeit -noprompt -alias mycert -file /tmp/examplecert.crt

If you are using a certificate signed by a Certificate Authority that is not included in the Java cacerts file by default, you need to complete the following configuration for HTTPS connections. To import certificates into cacerts:

1. Open Windows Explorer and navigate to the cacerts file, which is located in the jre\lib\security subfolder where AX Core Client is installed. The default location is C:\Program Files\ACL Software\AX Core Client\jre\lib\security
2. Create a backup copy of the file before making any changes.
3. Depending on the certificates you receive from the Certificate Authority you are using, you may need to import an intermediate certificate and/or root certificate into the cacerts file. Use the following syntax to import certificates: keytool -import -alias -keystore -trustcacerts -file
4. If you are importing both certificates the alias specified for each certificate should be unique.
5. Type the password for the keystore at the “Password” prompt and press Enter. The default Java password for the cacerts file is “changeit”. Type ‘y’ at the “Trust this certificate?” prompt and press Enter.

Might want to try

keytool -import -trustcacerts -noprompt -keystore <full path to cacerts> -storepass changeit -alias $REMHOST -file $REMHOST.pem

i honestly have no idea where it puts your certificate if you just write cacerts just give it a full path

The simple command 'keytool' also works on Windows and/or with Cygwin.

IF you're using Cygwin here is the modified command that I used from the bottom of "S.Botha's" answer :

1. make sure you identify the JRE inside the JDK that you will be using
2. Start your prompt/cygwin as admin
3. go inside the bin directory of that JDK e.g. cd /cygdrive/c/Program\ Files/Java/jdk1.8.0_121/jre/bin

4. Execute the keytool command from inside it, where you provide the path to your new Cert at the end, like so:

   ./keytool.exe -import -trustcacerts -keystore ../lib/security/cacerts  -storepass changeit -noprompt -alias myownaliasformysystem -file "D:\Stuff\saved-certs\ca.cert"
   

Notice, because if this is under Cygwin you're giving a path to a non-Cygwin program, so the path is DOS-like and in quotes.

install certificate in java linux

/opt/jdk(version)/bin/keytool -import -alias aliasname -file certificate.cer -keystore cacerts -storepass password