Update README

README

@@ -3,5 +3,68 @@ InstallCert.java
 Java program written by Andreas Sterbenz, and posted on a blog in Oct, 2006:
 https://blogs.oracle.com/gc/entry/unable_to_find_valid_certification
 
-Link to Java program no longer works, but the source was linked in another blog:
+Link to Java program in Andreas' blog no longer works, but the source was linked in another blog:
 http://nodsw.com/blog/leeland/2006/12/06-no-more-unable-find-valid-certification-path-requested-target
+
+Usage:
+Need to compile, first:
+javac InstallCert.java
+
+# Access server, and retrieve certificate (accept default certificate 1)
+java InstallCert [host]:[port]
+
+# Extract certificate from created jssecacerts keystore
+keytool -exportcert -alias [host]-1 -keystore jssecacerts -storepass changeit -file [host].cer
+
+# Import certificate into system keystore
+keytool -importcert -alias [host] -keystore [path to system keystore] -storepass changeit -file [host].cer
+
+# Example:
+java InstallCert woot.com:443
+
+    Loading KeyStore /usr/lib/jvm/java-6-sun-1.6.0.26/jre/lib/security/cacerts...
+    Opening connection to woot.com:443...
+    Starting SSL handshake...
+
+    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
+
+    <...>
+
+    Server sent 1 certificate(s):
+
+     1 Subject O=Woot Inc, C=US, ST=Texas, L=Carrollton, CN=*.woot.com
+       Issuer  CN=SecureTrust CA, O=SecureTrust Corporation, C=US
+       sha1    4b 46 ca 6b 83 05 b3 51 ff c6 e7 9c fd b3 9b e3 3f 2e c4 53 
+       md5     e8 a5 88 1b d5 67 bb fc 88 cc b1 c5 2b ac c4 7d 
+
+    Enter certificate to add to trusted keystore or 'q' to quit: [1]
+
+[enter]
+
+    [
+    [
+      Version: V3
+      Subject: O=Woot Inc, C=US, ST=Texas, L=Carrollton, CN=*.woot.com
+      Signature Algorithm: SHA1withRSA, OID = 1.2.840.113549.1.1.5
+
+    <...>
+
+    Added certificate to keystore 'jssecacerts' using alias 'woot.com-1'
+
+keytool -exportcert -alias woot.com-1 -keystore jssecacerts -storepass changeit -file woot.com.cer
+
+    geit -file woot.com.cer
+    Certificate stored in file <woot.com.cer>
+
+(sudo) keytool -importcert -alias woot.com -keystore /usr/lib/jvm/java-6-sun-1.6.0.26/jre/lib/security/cacerts -storepass changeit -file woot.com.cer
+
+    Owner: O=Woot Inc, C=US, ST=Texas, L=Carrollton, CN=*.woot.com
+    Issuer: CN=SecureTrust CA, O=SecureTrust Corporation, C=US
+
+    <...>
+
+    Trust this certificate? [no]:
+
+yes
+
+    Certificate was added to keystore