Yuestion $17(2\mathrm{.}78$ points$)$

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Alice is tired of sending confidential messages to Bob, so she decides to send a message $M$ so that "every body" can read it$.$ How she will send the message $M$ to Bob using public encryption. $($PrA$,$ PuA$)$ means Private and Public keys of Alice. $($PrB$,$ PuB$)$ means Priv

$C=E_{\text{P}\text{r}\text{A}}(M)$

$C=E_{PrB}(M)$

$C=E_{\text{P}\text{u}\text{B}}(M)$

$C=E_{\text{P}\text{u}\text{A}}(M)$