Cryptography Stack Exchange
Cryptography Stack Exchange

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.

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.

The CPU performs most computations in a computer and handles all task scheduling for the Operating System. It contains the General Processing Unit and Arithmetic Processing Unit of a computer, typically packaged together in a single chip.

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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. $n = 8192$ bits; $c = m^e \mod n$; In essence my question is how does the CPU deal…
artless-person
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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:…
Myria
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Proof of work designed for CPUs?

My naive understanding of proof-of-work algorithms is that they are essentially a p=np type problem where it's easy to check a solution, but difficult to produce a solution. I have recently read that some cryptocurrencies are based on algorithms…
user6916458
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Why does the GPU get a comparatively bigger advantage to the CPU when using higher parallelism in Argon2id?

My understanding is that the memory bandwidth of CPUs and GPUs is roughly one order of magnitude difference4, unlike cores which a GPU has many of and a CPU a handful. That is why PBKDF2-HMAC-SHA1 parallelizes very well (which needs 164 bytes of…
Luc
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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 by a software implementation, what post-processing…
Maarten Bodewes
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Is there anything like "Proof of Computation"?

Is there any cryptographic method for Proof Of Computation ? If i am running my program on untrusted hardware (remote server), after some time i want to verify the remote machine hasn't tampered with my program and successfully ran it for required…
fin
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Which sub operation is more expensive in the AES encryption process?

In the AES encryption process, there are various sub-operations, like SubByte, MixColumns, ARK etc. My question is which of these operations is more expensive? In a video lecture by Dan Boneh, it is mentioned that the lookup table implementation of…
Radium
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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 CPU?
mallea
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EC has lower CPU consumption than RSA under what condition?

When I searched Google, the top result said On average, processing for ECC is about four times less CPU-intensive than for RSA. Yeah, but under what condition? The page says "A 256-bit EC certificate (the minimum length supported) is roughly…
Damn Vegetables
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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 software implemented one?), I have a partial answer…
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/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 /dev/random needed for a crypto process? Is it only needed for the key…
user3200534
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Who has checked that AES-NI produces the expected results? (i.e. the exact same as software-only AES encryption)

Everybody seems to rely happily on the set of Intel instructions on > 2010 CPUs to accelerate AES256 encryption. This might be a too naive question but, being the exact algorithms an industrial secret, some independent experts must have checked at…
Mephisto
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Side channel attack: Why building an eviction set is possible?

I'm learning about the side channel attack on the cache. I came to know that most of the attack (EVICT + TIME, PRIME + PROBE, PRIME + ABORT) on the cache is initiated by building an eviction set(a group of virtual addresses that map to the same…
randomUser
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Encryption algorithm multiple threads/cores for higher throughput

There are situations where a single connection (or file) may require additional throughput available. While network bandwidth and CPU cores are available, they cannot be utilised. (Aside from means that are external to the algorithm as is) Some…
Kind Contributor
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Why Crypto++ library's AES definition is so fast

I am trying to compare the CPU cycle required for two encryption algorithms. One algorithm is AES and lets the other algorithm is B(code name). I implemented algorithm B and having fewer and simpler operations than AES and expected to take much less…
Radium
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