Algorithm 3 Data Decryption

Input:  Ciphertext $\langle {\mathit{CT}}_{\mathit{key}},{\mathit{CT}}_{\mathit{key}}^{\prime }\rangle$ or ${\mathit{CT}}_{\mathit{key}}$, access policy AP  Ciphertext of data CTdata  Digital digest DD  Users’ secret key skABPRE Output:  Agricultural product traceability data mdata 1: if skABPRE satisfies the access structure AP 2:  if ${\mathit{CT}}_{\mathit{key}}^{\prime }$ is provided then 3:    $kde\leftarrow VF-CP-ABPRE.ReDec\left({\mathit{sk}}_{ABPRE},{\mathit{CT}}_{key},{\mathit{CT}}_{key}^{\prime }\right)$ 4:  else 5:    $kde\leftarrow VF-CP-ABPRE.OriginDec\left({\mathit{sk}}_{ABPRE},{\mathit{CT}}_{key}\right)$ 6: end if 7: $mde\leftarrow AES.Dec\left(C{T}_{data},kde\right)$ 8: if $DD=SHA-256\left(mde\right)$ then 9:  return $m_{data}\leftarrow mde$ 10: else return ⊥