# All Questions

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### advantages of hashing over elliptic curve signatures for a proof of work protocol

I'm trying to create a proof-of-work protocol for a proof-of-concept software, and it's basically something like this: ...
108 views

### How to guarantee every plaintext is in a rainbow table?

This guide says that for a rainbow table or pre-computed hash chain, you can only get a probability that a plaintext is in a table, not a guarantee. Is there a way to guarantee every possible ...
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### Is Attribute based encryption sub-class of Identity based encryption [duplicate]

I have a basic question related to Identity and Attribute based encryption. Construction of IBE scheme was first shown by Boneh et al. in 2001 and I think in 2004 Sahai and Waters introduced ...
300 views

### Possible Digital Signature Hack?

I am starting to learn more about cryptography and I just read more about how asymmetric keys can make a digital certificate, and I would like if someone could explain me why the following case can't ...
93 views

### Montgomery Multiplication in FPGA explanation

I'm trying to implement an RSA module in a FPGA. I choose to use Montgomery multiplication. I've found a document where the Montgomery Multiplication is pretty clear. I don't understand only a step. ...
303 views

### Bouncy Castle elliptic curve from explicit parameters (E-521)

I'd like to use a curve that's not included in the Bouncy Castle EC named curves spec, specifically E-521. According to the BC javadocs, you need a few values in order to do this: q, a, and b for the ...
222 views

### fuzzy commitment implemenation to make secure biometric template

I want implement some ideas from an article that is about making secure biometric templates using fuzzy commitment and fuzzy vault. I need to implement just the fuzzy commitment (fuzzy commitment is a ...
94 views

### Scalar multiplication of elliptic curve point by a fraction

I'm implementing an algorithm that works on a generic finite cyclic group written in the classic multiplicative notation: (G,*) = < g > , n = |g| At a ...
64 views

### Advantages of using intermediate hash over full hash in digital signature application

Description of intermediate hashes Intermediate (or partial) hashes are canonical forms of digest state that can be transferred from one hash implementation to another, so that the other, limited ...
187 views

### RSA and ECDSA Certificate Sizes

Is there a table (or a whitepaper from official sources) that compares the size of X509 certificates generated with RSA (starting from 1024 bits) and ECDSA (starting from 160 bits) ? Thanks for the ...
60 views

### References and resources for learning to implement crypt. algorithms? [closed]

I wanted to learn about cryptography so they recommended me some of the books of Bruce Schneier. I'm now reading Cryptography Engineering and planning to follow with this one ...
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### becoming a cryptographer after math studies [duplicate]

After studying philosophy and being a philosophy teacher, I took back studies 4 years ago and I did a bachelor in maths. I'm in maths grad school now (I'm 32), and I would like to work in ...
326 views

### Why does WPA2-PSK use 4-way handshake instead of 2-way handshake

I don't seem to grasp why is the handshake for PTK in WPA2-PSK 4-way and not 2-way. Isn't it enough to just have these two steps: First party sends Nonce1 to the other party Second party sends to ...
109 views

### Example of CL PKC

I am trying to solve the example of algorithms of Certificateless Signature by manually and solving the mathematics of Algorithms but not succeed while doing mathematical calculations. Please ...
143 views

### Why is appending the key to a mesage and then hashing that insecure if the hash isn't weakly collision resistant? [duplicate]

Suppose I have H(M|K) and that H is not weakly collision resistant. If I have a message mac pair (M,MAC), how is it possible to find another message mac pair (M2,MAC2)? My thinking for this problem is ...
189 views

### Blind Signatures

The verification algorithm given in blind signature. Should it work for both Original message and the signature on it Blinded message and the signature on it. If yes, then how can we verify if ...
82 views

### Why is Merkle-Damgård construction insecure? [duplicate]

I've been reading about SHA-1. I read that SHA-1 is insecure as it uses the Merkle-Damgård construction and the Merkle-Damgård construction is — according to Wikipedia — susceptible to a variety of ...
189 views

### How to safely sign a 6 characters String?

I have to decide, whether a document, which I am given, was correctly signed by a private key. my Ideas is to sign the document id using RSA with the private key and to print the following onto the ...
113 views

### RSA vs El Gamal digital signature. Which is more secure? [duplicate]

I'm reading about the notions of security concerning digital signatures and I can't understand whether RSA is more secure than El Gamal digital signature. Well, they are both prone to forgery, but I ...
79 views

### PKCS#11: Which CKK_types are supported by CKM_PKCS5_PBKD2?

On Solaris there's a function pkcs11_PasswdToKey() which is a wrapper of C_GenerateKey(). I made a simple test and it turned out ...
67 views

### Strength of Combining Hash functions [duplicate]

If I combine two hash functions, what will the impact on the strength of the resulting function. If I combine in following way: H1*H2 (multiply) H1 + H2 (concat) H1 Xor H2 H1 (H2) EDIT: Lets say H1 ...