Enhancing Memory Security with H2ORAM and Secure Memory Techniques
H
2
ORAM
: Low Response
Latency Optimized ORAM for
Hybrid Memory Systems
Wenpeng He, Fang Wang, Dan Feng
School of Computer Science and Technology, Wuhan National Laboratory for
Optoelectronics Huazhong University of Science and Technology
ICCD 2020
ICCD 2020
2
S
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c
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r
e
M
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m
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y
1
Trusted
User
Adversary
Memory
Bus
Snoop
Encrypted
Data
Untrusted
Untrusted
Cloud
3
S
e
c
u
r
e
M
e
m
o
r
y
1
Trusted
User
Adversary
Memory
Bus
Snoop
Encrypted
Data
Untrusted
Untrusted
Cloud
✓
Data is safe!
✘
Memory access pattern can leak!
Oblivious-RAM (ORAM)
is a mechanism
for protecting memory access patterns
4
P
a
t
h
O
R
A
M
9
Data blocks stored in a
full binary tree
Each node is a
bucket
that can contain several blocks
There is one
path
from root to each leaf node
Each data block is
randomly
mapped
to a path
Tree contains both
real
and
dummy
blocks
A
fraction
of tree is always
dummy
Bucket
Path 0
Real Block
A
Dummy Block
5
P
a
t
h
O
R
A
M
A
c
c
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s
s
9
Access “
A
”
requires
2 path accesses
Position Map
A
Block A
Path 0
R
i
n
g
O
R
A
M
6
Read Path
•
Add
S
reserved dummy slots, permute buckets
•
Read Path
reads only 1 block per bucket
•
One block of interest + dummy from other buckets
•
To do so, it keeps
metadata
of blocks at each bucket and
prior to each Read Path it reads the metadata to know
exact location of real and dummy blocks in each bucket
•
Early Reshuffle
•
Reshuffle and rewrite each bucket that is accessed
S times
•
Evict Path
•
After each
A (e.g. 5)
accesses, it reads and writes an
entire path to reduce stash occupancy
•
This operation is similar to a regular access in Path ORAM
O
R
A
M
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n
H
y
b
r
i
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M
e
m
o
r
y
7
H
2
ORAM Optimization
8
•
LFUP-Aging
least frequently used
blocks are preferred for
eviction
•
Mask Slots
Duplicate leaves into
DRAM dummies
•
Mix
dynamically adjust
the number of
real/duplicate blocks
R
e
s
u
l
t
s
9
The
DRAM hit
ratio is increased from
36%
in the Hybrid to
72%
in the Mix
R
e
s
u
l
t
s
10
Response Latency Reduction
LFUP 4%
Mask 16%
Mix 44%
Overall Exe time Reduction
LFUP 2%
Mask 7%
Mix 18%
Explore cutting-edge research in memory security with topics such as H2ORAM optimization for hybrid memory systems, secure memory principles, Oblivious-RAM for data protection, Path ORAM storage structures, Ring ORAM for read paths, and the application of ORAM in hybrid memory architectures. These advancements aim to safeguard sensitive data from potential threats and ensure efficient memory access with low response latency.
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Presentation Transcript
H2ORAM: Low Response Latency Optimized ORAM for Hybrid Memory Systems Wenpeng He, Fang Wang, Dan Feng School of Computer Science and Technology, Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology ICCD 2020
Secure Memory Secure Memory1 Cloud User Encrypted Data Adversary Snoop Trusted Memory Bus Untrusted Untrusted 2
Secure Memory Secure Memory1 Data is safe! Cloud User Encrypted Data Oblivious-RAM (ORAM) is a mechanism for protecting memory access patterns Adversary Snoop Trusted Memory Bus Untrusted Untrusted Memory access pattern can leak! 3
Path ORAM Path ORAM 9 Real Block Data blocks stored in a full binary tree Dummy Block Each node is a bucket that can contain several blocks There is one path from root to each leaf node Bucket Each data block is randomlymapped to a path Tree contains both real and dummy blocks A A fraction of tree is always dummy Leaf 0 Leaf 1 Leaf 2 Leaf 3 Path 0 4
Path ORAM Access Path ORAM Access 9 Access A 1 Read path Write path 3 requires 2 path accesses A Leaf 0 Leaf 1 Leaf 2 Leaf 3 ORAM Tree (memory side) ORAM Controller (CPU side) On-chip PosMap Position Map Block A Path 0 Stash PLB Remap Block 2 5
Ring ORAM Ring ORAM Read Path Add S reserved dummy slots, permute buckets Read Path reads only 1 block per bucket One block of interest + dummy from other buckets To do so, it keeps metadata of blocks at each bucket and prior to each Read Path it reads the metadata to know exact location of real and dummy blocks in each bucket Early Reshuffle Reshuffle and rewrite each bucket that is accessed S times Evict Path After each A (e.g. 5) accesses, it reads and writes an entire path to reduce stash occupancy This operation is similar to a regular access in Path ORAM 6
ORAM in Hybrid Memory ORAM in Hybrid Memory 7
H2ORAM Optimization LFUP-Aging least frequently used blocks are preferred for eviction Mask Slots Duplicate leaves into DRAM dummies Mix dynamically adjust the number of real/duplicate blocks 8
Results Results The DRAM hit ratio is increased from 36% in the Hybrid to 72% in the Mix 9
Results Results Response Latency Reduction LFUP 4% Mask 16% Mix 44% Overall Exe time Reduction LFUP 2% Mask 7% Mix 18% 10
