Dear fei wang,
Hope you are doing great, as you may know the documentation regarding the ECC signature verification is available under NDA in Docstore, this means that this document should be share only with customers with active NDA and using a secured communication channel, if you have NDA please request this document using Docstore.
if you do not have NDA please contact you closest distributor Distributor Network | NXP in order to sign one and then get such documentation.
if you have any questions please let me know.
Have a great day !