Using Openssl And Keytool

generate a new private key and matching Certificate Signing Request (eg to send to a commercial CA)
openssl req -out MYCSR.csr -pubkey -new -keyout MYKEY.key
add -nodes to create an unencrypted private key
add -config <openssl.cnf> if your config file has not been set in the environment

decrypt private key
openssl rsa -in MYKEY.key >> MYKEY-NOCRYPT.key

generate a certificate siging request for an existing private key
openssl req -out MYCSR.csr -key MYKEY.key -new

generate a certificate signing request based on an existing x509 certificate
openssl x509 -x509toreq -in MYCRT.crt -out MYCSR.csr -signkey MYKEY.key

create self-signed certificate (can be used to sign other certificates)
openssl req -x509 -new -out MYCERT.crt -keyout MYKEY.key -days 365

sign a Certificate Signing Request
openssl x509 -req -in MYCSR.csr -CA MY-CA-CERT.crt -CAkey MY-CA-KEY.key -CAcreateserial -out MYCERT.crt -days 365
-days has to be less than the validity of the CA certificate


convert DER (.crt .cer .der) to PEM
openssl x509 -inform der -in MYCERT.cer -out MYCERT.pem

convert PEM to DER
openssl x509 -outform der -in MYCERT.pem -out MYCERT.der

convert PKCS#12 (.pfx .p12) to PEM containing both private key and certificates
openssl pkcs12 -in KEYSTORE.pfx -out KEYSTORE.pem -nodes
add -nocerts for private key only; add -nokeys for certificates only

convert (add) a seperate key and certificate to a new keystore of type PKCS#12
openssl pkcs12 -export -in MYCERT.crt -inkey MYKEY.key -out KEYSTORE.p12 -name "tomcat"

convert (add) a seperate key and certificate to a new keystore of type PKCS#12 for use with a server that should send the chain too (eg Tomcat)
openssl pkcs12 -export -in MYCERT.crt -inkey MYKEY.key -out KEYSTORE.p12 -name "tomcat" -CAfile MY-CA-CERT.crt -caname myCA -chain
you can repeat the combination of "-CAfile" and "-caname" for each intermediate certificate


check a private key
openssl rsa -in MYKEY.key -check
add -noout to not disclose the key

check a Certificate Signing Request
openssl req -text -noout -verify -in MYCSR.csr

check a certificate
openssl x509 -in MYCERT.crt -text -noout

check a PKCS#12 keystore
openssl pkcs12 -info -in KEYSTORE.p12

check a trust chain of a certificate
openssl verify -CAfile MYCHAINFILE.pem -verbose MYCERT.crt
trust chain is in directory (hash format): replace -CAfile with -CApath /path/to/CAchainDir/
to check for server usage: -purpose sslserver
to check for client usage: -purpose sslient


debug an SSL connection [server doesn't require certificate authentication]
openssl s_client -connect idp.example.be:443

debug an SSL connection with mutual certificate authentication
openssl s_client -connect idp.example.be:8443 -CAfile MY-CA-CERT.crt -cert MYCERT.crt -key MYKEY.key
trust chain is in directory (hash format): replace -CAfile with -CApath /path/to/CAchainDir/
send the starttls command (smtp or pop3 style): -starttls smtp or -starttls pop3


keytool

keytool does not support management of private keys inside a keystore. You need to use another tool for that. If you are using the JKS format, that means you need another java-based tool. extkeytool from the Shibboleth distribution can do this.

Create an empty keystore
keytool -genkey -alias foo -keystore truststore.jks
keytool -delete -alias foo -keystore truststore.jks

Generate a private key and an initial certificate as a JKS keystore
keytool -genkey -keyalg RSA -alias "selfsigned" -keystore KEYSTORE.jks -storepass "secret" -validity 360
you can also pass the data for the DN of the certificate as command-line parameters: -dname "CN=${pki-cn}, OU=${pki-ou}, O=${pki-o}, L=${pki-l}, S=${pki-s}, C=${pki-c}"

Generate a secret key that can be used for symmetric encryption. For this to work, you need to make use of a JCEKS keystore.
keytool -genseckey -alias "secret_key" -keystore KEYSTORE.jks -storepass "secret" -storetype "JCEKS"

Generate a Certificate Signing Request for a key in a JKS keystore
keytool -certreq -v -alias "selfsigned" -keystore KEYSTORE.jks -storepass "secret" -file MYCSR.csr

Import a (signed) certificate into a JKS keystore
keytool -import -keystore KEYSTORE.jks -storepass "secret" -file MYCERT.crt

add a public certificate to a JKS keystore, eg the JVM truststore
keytool -import -trustcacerts -alias "sensible-name-for-ca" -file CAcert.crt -keystore MYSTORE.jks
If the JVM truststore contains your certificate or the certificate of the root CA that signed your certificate, then the JVM will trust and thus might accept your certificate. The default truststore already contains the root certificates of most commonly used sommercial CA's. Use this command to add another certificate for trust:
keytool -import -trustcacerts -alias "sensible-name-for-ca" -file CAcert.crt -keystore $JAVA_HOME/lib/security/cacerts
the default password of the Java truststore is "changeit".
if $JAVA_HOME is set to the root of the JDK, then the truststore is it $JAVA_HOME/jre/lib/security/cacerts
keytool does NOT support adding trust certificates to a PKCS12 keystore (which is very unfortunate but probably a good move to promote JKS)

delete a public certificate from a JAVA keystore (JKS; eg JVM truststore)
keytool -delete -alias "sensible-name-for-ca" -keystore $JAVA_HOME/lib/security/cacerts
the default password of the Java truststore is "changeit".
if $JAVA_HOME is set to the root of the JDK, then the truststore is it $JAVA_HOME/jre/lib/security/cacerts

List the certificates inside a keystore
keytool -list -v -keystore KEYSTORE.jks
-storetype pkcs12 can be used

Get information about a stand-alone certificate
keytool -printcert -v -file MYCERT.crt