# Markus Maiwald (Architect) | Voxis Forge (AI)
# RUMPK CORE // CRYPTO
# Wrapper for Monocypher

{.push stackTrace: off, lineTrace: off.}

# Monocypher ABI
# int crypto_eddsa_check(const uint8_t sig[64], const uint8_t pub_key[32], const uint8_t *msg, size_t msg_size);
# Returns 0 on success, -1 on failure.
proc crypto_eddsa_check(sig: ptr uint8,
                       pub_key: ptr uint8,
                       msg: pointer,
                       msg_size: csize_t): cint
                       {.importc: "crypto_eddsa_check", header: "monocypher.h".}

# The Root of Trust (Hardcoded Public Key for now)
# Enforce 16-byte alignment because Monocypher v4 uses SIMD ldp/stp (Q registers)
# Using 'let' to ensure it resides in initialized data section.
let ROOT_PUB_KEY* {.align: 16.}: array[32, uint8] = [
  0x19'u8, 0xD3, 0xD9, 0x19, 0x47, 0x5D, 0xEE, 0xD4,
  0x69, 0x6B, 0x5D, 0x13, 0x01, 0x81, 0x51, 0xD1,
  0xAF, 0x88, 0xB2, 0xBD, 0x3B, 0xCF, 0xF0, 0x48,
  0xB4, 0x50, 0x31, 0xC1, 0xF3, 0x6D, 0x18, 0x58
]

proc verify_npl_signature*(sig: array[64, uint8], body_ptr: pointer,
    body_len: uint64): bool =
  # signature 'sig' is passed by value (copied on stack)
  # AArch64 stack is 16-byte aligned, so sig should be fine if we ensure it.
  var sig_aligned {.align: 16.} = sig

  let s_ptr = unsafeAddr sig_aligned[0]
  let p_ptr = unsafeAddr ROOT_PUB_KEY[0]

  let check_res = crypto_eddsa_check(s_ptr, p_ptr, body_ptr, cast[csize_t](body_len))

  return check_res == 0

{.pop.}