Users Manual

ALL
EFFECTIVITY
© Honeywell International Inc. Do not copy without express permission of Honeywell.
Page 7-3
22 Apr 2019
23-15-49
SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
ASPIRE-400
(2) The SDU uses a dual secure boot mechanism that:
(a) Employs code signature attached to all stage 2 boot and application images for
validation:
1 Signatures derived from encryption of a SHA_256 hash of the image
using a RSA private key
2 Signatures checked by SW RSA verification that compares a SHA_256
hash of the image with the hash obtained by applying a RSA public key
to decrypt the signature
3 The RSA private and RSA public keys are a mated pair.
(b) Follows the startup sequence of:
1 HW implements the stage 1 boot
2 HW (via HW circuitry) authenticates the stage 2 boot image
3 SW RSA authentication of both application images by the stage 2 boot.
(3) ACD Boot preserves the HW power-up state of:
(a) Output discretes open
(b) All subordinate processors shutdown
(c) RF output disabled
(d) All Ethernet ports disabled except for the dedicated ACD Ethernet port
(e) Audio outputs disabled.
(4) ACD Boot keeps all subordinate processors shutdown. The SDU provides a connection
for a RS-232 serial port with the following characteristics:
(a) The baud rate is 115200 baud
(b) The number of data bits is 8 bits
(c) The number of stop bits is 1 bit
(d) The parity is None
(e) The flow control is None.
(5) ACD Boot ensures that the power output over coax interface is off. The ACD stage 1
(mini) boot code activates either:
(a) The primary stage 2 boot image
(b) The secondary stage 2 boot image if the primary stage 2 boot image is
nonfunctional.
(6) The ACD stage 2 boot image configures the hardware to alternatively flash the front
panel green power and red LEDs. The stage 2 boot image increments a count in non-
volatile memory to indicate the number of times boot has been activated since the last
time application code was activated.
(7) The ACD stage 2 boot image performs the following SDU POST tests:
(a) ACD RAM Memory check
(b) Application Image validity check.
(8) And respond to failures by:
DRAFT
3rd rvw Draft as of:
29 January, 2020