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

Question

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

    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"

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 

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 <alias> -keystore <cacerts_file> -trustcacerts -file <certificate_filename>

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.

You can use keytool with your Java installation and should be in $JAVA_HOME/bin. The Java keystore is located in $JAVA_HOME/lib/security/cacerts or $JAVA_HOME/jre/lib/security/cacerts which depends on if you have the JDK or JRE installed.

If using Java 9 or later, you don't need to know the exact location. You can use the -cacerts option as a shortcut.

Java 9+

So with Java 9 (aka Java 1.9) or later, simply use

keytool -importcert -trustcacerts -cacerts -file myCert.pem -alias myCert

Earlier Java versions

With Java 8 (aka 1.8) or older, you must specify the keystore location like so

keytool -importcert -trustcacerts $JAVA_HOME/lib/security/cacerts -file myCert.pem -alias myCert

With Java 5 (aka 1.5) or older, the -importcert option did not exist. It was called -import, but otherwise it's identical. So use

keytool -import -trustcacerts $JAVA_HOME/lib/security/cacerts -file myCert.pem -alias myCert

Additional options

• You will be asked for the truststore password, The default password is changeit.
• If you need to run the import unattended, you can add -storepass changeit -noprompt
• In some older Java version (which I don't know), -importcert did not exist, but you could simply use -import, should you ever stumble upon such an old version.

Formats

keytool can import X.509 v1, v2, and v3 certificates, and PKCS#7 formatted certificate chains consisting of certificates of that type (P7B). The data to be imported must be provided

• either in binary encoding format (DER)
• or in printable encoding format (aka base64 encoded), enclosed in -----BEGIN and -----END lines (PEM)

Note: I'm not sure if certificate chains in PEM format really work.

Bonus script

I'm afraid, it's bash, so no solution for Windows users.

This simple script, created thanks to several useful questions and smart answers here on stackoverflow, checks the Java version and - if necessary - determines the correct keystore location, and it can import multiple certificates in one command. Note that you must pass the file pattern argument in single quotes (see usage).

addcerts.sh

#!/bin/bash

# Add custom root certificates to Java trust store

if [ "$#" -ne 1 ]; then
    SCRIPT=`basename "$0"`
    echo "Usage: $SCRIPT 'path/to/certs/*'"
    exit 1
fi

CERTFILES=$1    

JAVA_VERSION=`java -version 2>&1 | head -1 | cut -d'"' -f2 | sed '/^1\./s///' | cut -d'.' -f1`

if (( $JAVA_VERSION >= 9 )); then
    CACERTS="-cacerts"
else    
    # Check where cacerts are located
    # differs depending or jdk or jre installed
    if [ -d "$JAVA_HOME/jre" ]; then
        CACERTS="$JAVA_HOME/jre"
    else
        CACERTS="$JAVA_HOME"
    fi
    CACERTS="-keystore $CACERTS/lib/security/cacerts"   
fi      

# Now add certificates 
for CERTFILE in $CERTFILES; do
    # Remove path, then suffix to derive alias from filename
    ALIAS=${CERTFILE##*/}  
    ALIAS=${ALIAS%.*}
    $JAVA_HOME/bin/keytool -importcert -file "$CERTFILE" -alias "$ALIAS" $CACERTS -trustcacerts -storepass changeit -noprompt
    if [ $? -ne 0 ]; then
        echo "Failed to add $CERTFILE as $ALIAS to $CACERTS"
        exit 1
    fi  
done