In identity-based encryption (IBE) the public key of a user $A$ is some identity string $ID_A$, e.g., an email address. To encrypt a message for this user there is no need to retrieve an authentic copy of the public key, as it is in public key cryptography, but one can simply use the identity string ...

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System parameters in identity-based encryption

In IBE schemes, the system parameters are $(q, \mathbb{G}, F, \hat{e}, P, Q, T, H_1)$. I don't know $\hat{e}$. For example, in type A pairing… ...
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How to define order according to domain parameters in elliptic curve pairing groups

According to domain parameters, as an example Type 1 pairing domain parameters are ...
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How to select corresponding ciphertext in anonymous Identity-based broadcast encryption

In identity-based broadcast encryption, suppose the broadcast ciphertext $(r_1,r_2,\dots,r_i,U,W,V)$ is sent to the receiver. It does not describe which user corresponds to which ciphertext part. User ...
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Boneh/Franklin Identity based encryption with Tate pairing

Boneh/Franklin developed an identity based encryption scheme based on the Weil Pairing. This algorithm has also been standardised in IEEE P1363.3 . I know that this algorithm can also be implemented ...
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User revocation in Identity Based Encryption

I read several papers about user revocation in IBE recently. A common point is that when a user is revoked, some other valid users should also update their private keys. Does this mean that one ...
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Example describing Baek and Zheng’s threshold identity-based decryption scheme

I am trying to work through an example of Baek and Zheng’s “threshold identity-based decryption scheme” and I tried a lot to solve this, but somewhere I’m doing something wrong. I hope someone can ...
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How to compare different signature scheme's performance?

I am interested in comparing the computational performance of two signature schemes. However, I am unsure how to do that. My candidates are RSA and Shamir's ID Based Signature scheme. To get a fair ...
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Could MITM securely identify identity?

Consider protocol like QUIC or MinimaLT which are essentially layer4 replacement for TCP/UDP (riding on top of UDP currently because of fear of random firewalls dropping new L4 protocol). From crypto ...
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Notation of * in hash function of identity-based encryption

$H:\{0,1\}^{*} \rightarrow Z_{p}^{*}$ $H:\{0,1\}^{*} \rightarrow Z_{p}$ $H:\{0,1\}^{*} \rightarrow G_{1}^{*}$ $H:\{0,1\}^{*} \rightarrow G_{1}$ Difference meaning of $Z_{p}^{*}, Z_{p},G_{1}^{...
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Security Level Same or not in key extraction of identity-based encryption

In identity-based encryption, key generation is performed using ($s$) as a secret key for identity a as in (eq.1) $\bullet$ $Priv_{a}=s.H(ID_{a})$(eq.1) If key is generated as follows, $\bullet$ $...
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Security for this scheme or not in pairing

Let be $G_{1}$and $G_{2}$ cyclic groups of prime order $q$ and $g =<G1>$ and $h=<G2>$ the generators of these groups. Let's consider the following protocol: Select $s \leftarrow 1,2,3,.....
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Do users need to know decryption scheme in Identity-based broadcast encryption?

I have a question related to identity-based broadcast encryption: For decryption, there are different decryption schemes. Does the user need to know that scheme, or does the system firmly define the ...
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Identification schemes: Okamoto

I am reading Cryptography theory and practice by Stinson. The book is talking about the proof of security of Schnorr and Okamoto schemes. It claims that if an impersonater can find (in the case of the ...
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Problem of revealing master secret key of others in identity-based encryption (ECDLP)

Please help me to consider the case where Server B tries to get the same master secret key of Server A. Server B ask private key for IDA from Server A. Then Server B extracts private key for same ...
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BDH Problem or Guessing Problem or Discrete Logarithmic Problem

In identity-based encryption, $P\in G1,s\leftarrow Z_{q}, Pub=sP$, Given $P,Pub$ Finding $s$ value, by repeatedly generating random $x$ value. Checking whether estimated value $EstPub=xP$ is ...
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Secret Key Encryption in identity based encryption

If we assume $x$ be secret value $x\leftarrow{0,1,2,....,q-1}$ where q is a prime number Instead of using public key encryption schemes, using a function such as $f(x)=x*y/z$ to conceal $x$ value ...