# Okay to post homework
# Ryan Badi, April 21, 2024, Homework 24

FieldTripAvailability := proc():
  return {}:
end:

AliceToBobG := proc(ListM, Nbob, eBob, Nalice, dAlice, H) local x, M1, S, M:
  M1 := [seq(M&^eBob mod Nbob, M in ListM)]:
  x := add(M&^3, M in ListM) mod H:
  S := x&^dAlice mod Nalice:
  return [M1, S]:
end:

BobReadAliceG := proc(MS, Nbob, dBob, Nalice, eAlice, H) local M1, S, M, X, x, X1, Mi, Mj:
  M1 := MS[1]:
  S := MS[2]:
  M := [seq(Mi&^dBob mod Nbob, Mi in M1)]:
  X := [seq(Mj&^3 mod H, Mj in M)]:
  X1 := S&^eAlice mod Nalice:
  if {seq(x, x in X)} <> {X1} then
    printf("Incorrect signature.\n"):
  fi:
  return M:
end:

# I have sent four messages (three to those immediately following me in the mailing list, and one to Himanshu, whose name was omitted). The following are my results:
# Ramesh: Correctly determined my birthday and verified I authored the message.
# Shaurya: Correctly determined my birthday and verified I authored the message.
# Pablo: Correctly determined my birthday and determined someone fraudulently signed the message with my name.
# Himanshu: Correctly determined my birthday and verified I authored the message.

# I have received two messages.
# Alex Valentino: I have not received a message.
# Alex Varjabedian: Correctly determined his birthday and verified he authored the message.
# Kaylee: Correctly determined her birthday and determined someone fraudulently signed the message with her name.