[U-Boot] Secure booting

[JYOTI DUBEY]

Can I obtain information as how secure booting works.How the keys and
certificates are generated and also encryption and decryption steps
involved in the authentication process. i would like to know just the
theory behind it not and commands or technical details.
I have attached pictorial representation of 3 consecutive steps involved in
secure booting but while I tried to understanding the working though the
diagram I felt that authentication might never succeed as no decryption is
taking place.Can anyone please inform how the steps are taking place? I
have also attached the documentation related to high assurance booting.
Thanks in Advance!
-------------- next part --------------
A non-text attachment was scrubbed...
Name: High_Assurance_Boot_L3.0.35_1.1.0.pdf
Type: application/pdf
Size: 296783 bytes
Desc: not available
URL: <http://lists.denx.de/pipermail/u-boot/attachments/20140213/3dce00f8/attachment.pdf>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 1.png
Type: image/png
Size: 14296 bytes
Desc: not available
URL: <http://lists.denx.de/pipermail/u-boot/attachments/20140213/3dce00f8/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 2.png
Type: image/png
Size: 8068 bytes
Desc: not available
URL: <http://lists.denx.de/pipermail/u-boot/attachments/20140213/3dce00f8/attachment-0001.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 3.png
Type: image/png
Size: 15034 bytes
Desc: not available
URL: <http://lists.denx.de/pipermail/u-boot/attachments/20140213/3dce00f8/attachment-0002.png>