how to apply my own logic for nameId

[Itay Moav]

Is there a way I apply my own logic to generate the nameId field value?

I saw there was a way to copy the core field value from an attribute, but

then SimpleSamlePHP hash it with IdP+SP+SALT.  

For what I need, I need full control on how this value is generated.

(For the curious, I need to generate a dump of all my users with that value as identifier  and share that dump with two different vendors).

[Itay Moav]

In other words, Can I create my own filter to generate the nameid field?

I do not mean to copy it's value into an attribute.