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Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 776
UG585 (v1.11) September 27, 2016
Chapter 32: Device Secure Boot
32.4 Programming Considerations
Although most of the secure boot process is handled by the BootROM, it is possible to decrypt PS
images or PL bitstreams after the initial boot. To decrypt secure images the PL must be powered on.
The PL is powered on and ready to accept new encrypted data if the PCFG_INIT bit of the Device
Configuration Interface (DevC) Status register is set.
To send encrypted data to the PL for decryption, the PCAP_MODE and PCAP_PR bits of the DevC
Control register must be set to 1. Because the AES engine decrypts data one byte at a time, the
QUARTER_PCAP_RATE_EN bit on the DevC Control register must also be set to 1.
To disable the AES and HMAC engines, the three PCFG_AES_EN bits of the DevC Control register must
be set to 0. All three bits must be set with the same register write or a security violation occurs,
resulting in a security lockdown of the device. Once the AES and HMAC engines have been disabled,
they cannot be enabled again without a power-on-reset.
Table 32-4: RSA Authentication Options in Non-secure Mode
BootROM RSA User SW RSA AES / HMAC
FSBL Yes No No
PL Bitstream No User Option No
u-Boot No User Option No
Linux No User Option No
Applications No User Option No
Table 32-5: Secure Boot Options without RSA Authentication Enabled
BootROM RSA User SW RSA AES / HMAC
FSBL No No Yes
PL Bitstream No User Option User Option
u-Boot No User Option User Option
Linux No User Option User Option
Applications No User Option User Option
Table 32-6: Secure Boot Options with RSA Authentication Enabled
BootROM RSA User SW RSA AES / HMAC
FSBL Yes No Yes
PL Bitstream No User Option User Option
u-Boot No User Option User Option
Linux No User Option User Option
Applications No User Option User Option