Mini Forensic Tool: The sender and receiver shared a symmetric key k1 as the root key. (E,D) denote a symmetric encryption and decryption algorithm, respectively. Using AES as the symmetric cipher with 256-bit key. H denotes a secure cryptographic hash function. Chose SHA-256. Used available functions from MIRACL library to realize (E, D, H). (l, t) are RID parameters.
Sender Algorithm: processing i’th data item Mi (i > 1)
1) Mi′ ← Compress(Mi)
2) ci ←Eki(Mi′)
3) si ← HMACki (ci||i)
4) s1,i ← H(s1,i−1||si)
5) ki+1 ← H(ki)
6) Delete (ki, si, s1,i−1) from the memory, i ← i + 1.
7) Finally, the sender reaches the state n, wherein the collector comes to collect the encrypted data items and their aggregate authentication tag denoted as V =(⟨c1,...,cn⟩,s1,n). The sender applies RID as V′ ← Dispersal(V,l,t), and uploads V ′ to the collector.
Receiver Algorithm: Lets assume the receiver (i.e., collector) receives at least l pieces out of t as required by RID.
1) V ←Recover(V′,l,t),whereV =(⟨c1,...,cn⟩,s1,n)
2) kj+1 ← H(kj), j = 1,...,n
3) sj ← HMAC(cj||j), j = 1,...,n
4) s′1,n ← H(s1,j−1||sj), j = 2,...,n, computed recursively, where the base case
is s1,1 = s1.
5) If s′1,n ̸= s1,n then abort, else continue.
6) Mj′ ←Dkj(cj),j=1,...,n
7) Mj ← Decompress(Mj′) j = 1,...,n
8) The receiver recovers the telemetry (M1, . . . , Mn).