[xwiki-users] java.security.NoSuchAlgorithmException

Hi everybody, I'm working with XWiki 3.5.1 deployed on Tomcat 7 and I always have the same error in Tomcat logs when I try to submit a form : ERROR c.x.x.o.c.PasswordClass - Wrong hash algorithm [custom] in [null] java.security.NoSuchAlgorithmException: custom MessageDigest not available at sun.security.jca.GetInstance.getInstance(Unknown Source) ~[na:1.7.0_45] at java.security.Security.getImpl(Unknown Source) ~[na:1.7.0_45] at java.security.MessageDigest.getInstance(Unknown Source) ~[na:1.7.0_45] at com.xpn.xwiki.objects.classes.PasswordClass.getPasswordHash(PasswordClass.java:220) [xwiki-platform-legacy-oldcore-3.5.1.jar:na] at com.xpn.xwiki.objects.classes.PasswordClass.getPasswordHash(PasswordClass.java:213) [xwiki-platform-legacy-oldcore-3.5.1.jar:na] at com.xpn.xwiki.objects.classes.PasswordClass.getProcessedPassword(PasswordClass.java:193) [xwiki-platform-legacy-oldcore-3.5.1.jar:na] at com.xpn.xwiki.objects.classes.PasswordClass.fromString(PasswordClass.java:75) [xwiki-platform-legacy-oldcore-3.5.1.jar:na] at com.xpn.xwiki.objects.BaseObject.set(BaseObject.java:456) [xwiki-platform-legacy-oldcore-3.5.1.jar:na] Do you know how I could solve this problem ? Thanks ! Pierrick