Apr 5, 2018

Export private key from a Java Keytool keystore

Use Java keytool to convert from JKS to P12...

Export from keytool's proprietary format (called "JKS") to standardized format PKCS #12:
keytool -importkeystore -srckeystore keystore.jks -destkeystore keystore.p12
-deststoretype PKCS12 -srcalias <jkskeyalias> -deststorepass <password>
-destkeypass <password>
For example:
sudo keytool -importkeystore -srckeystore keystore.jks -destkeystore keystore.p12  -deststoretype PKCS12 -srcalias s1as -deststorepass changeit -destkeypass changeit

then use openssl to export from P12 to PEM

Export certificate using openssl:
openssl pkcs12 -in keystore.p12  -nokeys -out cert.pem
Export unencrypted private key:
openssl pkcs12 -in keystore.p12  -nodes -nocerts -out key.pem