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Efficiently Computing Data-Independent Memory-Hard Functions [chapter]

Joël Alwen, Jeremiah Blocki
2016 Lecture Notes in Computer Science  
A data-independent MHF (iMHF) has the added property that it can be computed with almost optimal memory and time complexity by an algorithm which accesses memory in a pattern independent of the input value  ...  A memory-hard function (MHF) f is equipped with a space cost σ and time cost τ parameter such that repeatedly computing fσ,τ on an application specific integrated circuit (ASIC) is not economically advantageous  ...  An data-independent memory-hard function (iMHF) is a function f for which the associated naïve algorithm N , on input x, computes f (x) using a memory access pattern that is independent of x.  ... 
doi:10.1007/978-3-662-53008-5_9 fatcat:mmemp2rvkzhwljr3i7xbk3lqqi

Bandwidth Hard Functions for ASIC Resistance [chapter]

Ling Ren, Srinivas Devadas
2017 Lecture Notes in Computer Science  
CPUs cannot compete with ASICs for energy efficiency in computation, but we can rely on memory accesses to reduce an ASIC's energy advantage because energy costs of memory accesses are comparable for ASICs  ...  The standard approach towards ASIC resistance today is through memory hard functions or memory hard proof of work schemes.  ...  Thus, it is interesting to also look for data-independent bandwidth hard functions, especially those that achieve bandwidth hardness with a smaller memory footprint.  ... 
doi:10.1007/978-3-319-70500-2_16 fatcat:unrob26zazdarb4pbnz6efgo6y

Open Sesame: The Password Hashing Competition and Argon2 [article]

Jos Wetzels
2016 arXiv   pre-print
[43] hashing schemes that aim for memory-hardness can be divided into data-independent schemes (which access memory blocks according to a predefined pattern independent of data input) and data-dependent  ...  functions with data-dependent indexing functions protecting more against the former but being more vulnerable to the latter and vice-versa for data-independent functions.  ... 
arXiv:1602.03097v2 fatcat:cvsjzq4wifbp7kkcktsuiisy7a

Demystifying Crypto-Mining: Analysis and Optimizations of Memory-Hard PoW Algorithms

Runchao Han, Nikos Foutris, Christos Kotselidis
2019 2019 IEEE International Symposium on Performance Analysis of Systems and Software (ISPASS)  
In this paper, we perform an in-depth performance analysis and characterization of the most common memory-hard PoW algorithms running on NVIDIA GPUs.  ...  The implemented optimizations accelerate performance by 14% and improve energy efficiency by 10% when executing on three NVIDIA GPUs.  ...  This is attributed to the fact that the memory segment usage on a specific iteration of the memoryhard loop is efficiently interleaved with data-independent operations.  ... 
doi:10.1109/ispass.2019.00011 dblp:conf/ispass/HanFK19 fatcat:vydexmzt7jfcrpclkesw2mjnim

Password-Hashing Status

George Hatzivasilis
2017 Cryptography  
A problem was found in building secure data-independent memory-hard functions [22] [23] [24] [25] . The affected PHC schemes were revisited and addressed the aforementioned issues.  ...  The competition advanced our knowledge in password-hashing and enhanced a trend of memory-hard functions, applied by the winner and most of the honourable finalists.  ...  MAKWA consumes a constant amount of memory and operates on big number computations like RSA. Parallel imposes computational hardness and is more efficient than the related PBKDF2.  ... 
doi:10.3390/cryptography1020010 fatcat:klnw5tucinfwfoxwe5zlpsepwi

Time-Memory Tradeoff Attacks on the MTP Proof-of-Work Scheme [chapter]

Itai Dinur, Niv Nadler
2017 Lecture Notes in Computer Science  
The scheme uses a Merkle hash tree construction over a large array of blocks computed by a memory consuming (memory-hard) function.  ...  We apply our attack to the concrete instance proposed by the designers which uses the memory-hard function Argon2d and computes a proof by allocating 2 gigabytes of memory.  ...  The most natural way to avoid the attack is to use a memory-hard function with data-independent indexing (such as Argon2i).  ... 
doi:10.1007/978-3-319-63715-0_13 fatcat:cpa5asa3o5emdehyfls7vgh7be

Egalitarian computing [article]

Alex Biryukov, Dmitry Khovratovich
2018 arXiv   pre-print
Based on existing schemes like Argon2 and the recent generalized-birthday proof-of-work, we suggest a generic framework and two new schemes: MTP, a memory-hard Proof-of-Work based on the memory-hard function  ...  We suggest memory-hard computing as a generic paradigm, where every task is amalgamated with a certain procedure requiring intensive access to RAM both in terms of size and (very importantly) bandwidth  ...  It differs from MTP-Argon2 in smaller 64-byte blocks, full-blown Blake2b for the internal compression function F and two data-dependent memory accesses per block (plus two more data-independent ones).  ... 
arXiv:1606.03588v2 fatcat:deazhh5s35cj7aeatig4dnqnny

Computer hardware for radiologists: Part I

IK Indrajit, A Alam
2010 Indian Journal of Radiology and Imaging  
"Drive interfaces" connect hard drives and optical drives to a computer. The connections of such drives require both a power cable and a data cable.  ...  The "bus" is a built-in electronic signal pathway in the motherboard to permit efficient and uninterrupted data transfer.  ...  It permits efficient and uninterrupted data transfer. They are also referred to as data channels or data pathways.  ... 
doi:10.4103/0971-3026.69346 pmid:21042437 pmcid:PMC2963745 fatcat:gmsrmkob2jbppm44v3emmej6wu

Computer hardware for radiologists: Part 2

IK Indrajit, A Alam
2010 Indian Journal of Radiology and Imaging  
"Drive interfaces" connect hard drives and optical drives to a computer. The connections of such drives require both a power cable and a data cable.  ...  The "bus" is a built-in electronic signal pathway in the motherboard to permit efficient and uninterrupted data transfer.  ...  Memory Storage Drives Storage drive is a term describing a "memory" hardware used to store or retrieve data. The data may be text, images, audio, video, etc.  ... 
doi:10.4103/0971-3026.73527 pmid:21423895 pmcid:PMC3056617 fatcat:zpb7el3v7raklbja2gbiwp2da4

Tradeoff Cryptanalysis of Memory-Hard Functions [chapter]

Alex Biryukov, Dmitry Khovratovich
2015 Lecture Notes in Computer Science  
We explore time-memory and other tradeoffs for memory-hard functions, which are supposed to impose significant computational and time penalties if less memory is used than intended.  ...  We show that using M 2/3 memory instead of M we may have no time penalties. We further generalize our method for a wide class of schemes with predictable memory access.  ...  In this paper we have analyzed memory-hard functions Catena and Lyra2.  ... 
doi:10.1007/978-3-662-48800-3_26 fatcat:ixi5pnn355chzjthlbfvdpgati

A PRET architecture supporting concurrent programs with composable timing properties

Isaac Liu, Jan Reineke, Edward A. Lee
2010 2010 Conference Record of the Forty Fourth Asilomar Conference on Signals, Systems and Computers  
In order to improve design time and efficiency of systems, large scale system design is often split into the design of separate functions, which are later integrated together.  ...  Thus, it is difficult, if not impossible, to integrate two functions on a modern computer architecture while preserving their separate timing properties.  ...  This realization provides interference-free concurrent execution of multiple contexts to allow for simple and efficient integration of multiple independent functions. D.  ... 
doi:10.1109/acssc.2010.5757922 fatcat:tbqmh3mmjngq3f5gwi75mcugky

A Time-Aware Fault Tolerance Scheme to Improve Reliability of Multilevel Phase-Change Memory in the Presence of Significant Resistance Drift

Wei Xu, Tong Zhang
2011 IEEE Transactions on Very Large Scale Integration (vlsi) Systems  
Under this time-aware fault tolerance framework, we study the use of two types of ECCs, including classical codes such as BCH that only demand hard-decision input and advanced codes such as low-density  ...  performance advantages of such time-aware memory fault tolerance strategy in the presence of significant memory cell resistance drift.  ...  First, we study and compare the raw BER when using time-independent and time-aware hard-decision memory cell resistance quantization.  ... 
doi:10.1109/tvlsi.2010.2052640 fatcat:arh6cjkgtra3ldfbibetz4z67y

Proof of Space from Stacked Expanders [chapter]

Ling Ren, Srinivas Devadas
2016 Lecture Notes in Computer Science  
A closely related notion is memory-hard functions (MHF), functions that require a lot of memory/space to compute. While making promising progress, existing PoS and MHF have several problems.  ...  We show Balloon hash has tighter space-hardness than previously believed and consistent space-hardness throughout its computation.  ...  While the space-hardness gap for Balloon hash and our PoTS can be made arbitrarily small, pushing it towards the limit would lead to very large constants for efficiency.  ... 
doi:10.1007/978-3-662-53641-4_11 fatcat:fz5nszj5jngtpmaqtpnvw427j4

Balloon Hashing: A Memory-Hard Function Providing Provable Protection Against Sequential Attacks [chapter]

Dan Boneh, Henry Corrigan-Gibbs, Stuart Schechter
2016 Lecture Notes in Computer Science  
Memory-hard functions require a large amount of working space to evaluate efficiently and, when used for password hashing, they dramatically increase the cost of offline dictionary attacks.  ...  This is the first practical cryptographic hash function that: (i) has proven memory-hardness properties in the random-oracle model, (ii) uses a password-independent access pattern, and (iii) meets or exceeds  ...  A function that is memory-hard and that uses a password-independent data access pattern must be impervious to all small-space strategies for computing the function so that it maintains its strength in  ... 
doi:10.1007/978-3-662-53887-6_8 fatcat:suv2aimhkvcelggdqh45jmgfie

Algorithms of Two-Level Parallelization for DSMC of Unsteady Flows in Molecular Gasdynamics [article]

Alexander V. Bogdanov, Nick Yu. Bykov, Igor A. Grishin, Gregory O. Khanlarov, German A. Lukianov, Vladimir V. Zakharov
1999 arXiv   pre-print
The high efficient algorithm of parallel independent runs is used on the first level. The data parallelization is employed for the second one.  ...  The general scheme of two-level parallelization (TLP) for direct simulation Monte Carlo of unsteady gas flows on shared memory multiprocessor computers has been described.  ...  This algorithm can be realized on computers with any type of memory (shared or local). The message passing is used to perform data exchange on computers with local memory.  ... 
arXiv:cs/9902024v1 fatcat:hx5aq22hqnbxjiczramyixmwvy
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