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Questions tagged [cpu]

The central processing unit is the most important hardware component of a computer system, since it contains the circuitry necessary to interpret and execute instructions.

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2answers
277 views

Fastest way to compute iterates of SHA1

It's well-known that computing lots of hash functions (like SHA1) in parallel involves the use of GPUs in most cases. However, when doing something serially, such as computing ...
3
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1answer
75 views

What exactly are an untrusted memory and a trusted CPU?

In the use of SGX and Oblivious RAM. There sometimes exist the notions untrusted memory and trusted processor. What are the intuitions of those? Can memory easily be hacked by adversaries? What about ...
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3answers
1k views

Usage difference between x86 RDRAND and RDSEED

Modern x86 CPUs often have the RDRAND and RDSEED instructions for hardware generation of random numbers. I just don't understand the difference between them. Intel has this document: https://...
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2answers
88 views

Why is on-chip data considered to be secure in secure processor setting?

I was taking a look into the paper PHANTOM: Practical Oblivious Computation in a Secure Processor. The introduction says, Confidentiality of data is a major concern for enterprises and ...
2
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6answers
4k views

Running Crypto on hardware — e.g., AES in hardware

I am trying to understand the difference between a crypto algorithm run in hardware from that run in software. From a previous post (see here: Difference between Hardware implemented algorithm and ...
38
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5answers
8k views

In RSA, how does the CPU deal with this huge modulus (8192 bits)?

Whilst I understand how the RSA algorithm works, I don't understand how the CPU operates when it needs to use the mod function with a huge number $n$, for example. ...
2
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1answer
152 views

/dev/random only needed for key generation / CPU pattern encryption

Consider the following scenarios: using OpenSSL to encrypt a file with Rijndael-256 using LUKS to encrypt a hard-drive that is used every day Exactly when is entropy from ...
5
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2answers
318 views

Fast post-processing for broken RDRAND

Let's assume that the Intel RDRAND instruction does not return fully random numbers, e.g. because it has been engineered with a backdoor for the NSA. If the Intel RDRAND instruction is used directly ...