Cocks IBE scheme

Cocks IBE scheme is an identity based encryption system proposed by Clifford Cocks in 2001. The security of the scheme is based on the hardness of the quadratic residuosity problem.

The PKG chooses:

When user ${\displaystyle \textstyle ID}$ wants to obtain his private key, he contacts the PKG through a secure channel. The PKG

To encrypt a bit (coded as ${\displaystyle \textstyle 1}$/${\displaystyle \textstyle -1}$) ${\displaystyle \textstyle m\in {\mathcal {M}}}$ for ${\displaystyle \textstyle ID}$, the user

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