#! /usr/bin/python

from sys import argv
from struct import pack
from itertools import izip
import catacomb as C

R = C.FibRand(0)

###--------------------------------------------------------------------------
### Utilities.

def combs(things, k):
  ii = range(k)
  n = len(things)
  while True:
    yield [things[i] for i in ii]
    for j in xrange(k):
      if j == k - 1: lim = n
      else: lim = ii[j + 1]
      i = ii[j] + 1
      if i < lim:
        ii[j] = i
        break
      ii[j] = j
    else:
      return

POLYMAP = {}

def poly(nbits):
  try: return POLYMAP[nbits]
  except KeyError: pass
  base = C.GF(0).setbit(nbits).setbit(0)
  for k in xrange(1, nbits, 2):
    for cc in combs(range(1, nbits), k):
      p = base + sum(C.GF(0).setbit(c) for c in cc)
      if p.irreduciblep(): POLYMAP[nbits] = p; return p
  raise ValueError, nbits

def Z(n):
  return C.ByteString.zero(n)

def mul_blk_gf(m, x, p): return ((C.GF.loadb(m)*x)%p).storeb((p.nbits + 6)/8)

def with_lastp(it):
  it = iter(it)
  try: j = next(it)
  except StopIteration: raise ValueError, 'empty iter'
  lastp = False
  while not lastp:
    i = j
    try: j = next(it)
    except StopIteration: lastp = True
    yield i, lastp

def safehex(x):
  if len(x): return hex(x)
  else: return '""'

def keylens(ksz):
  sel = []
  if isinstance(ksz, C.KeySZSet): kk = ksz.set
  elif isinstance(ksz, C.KeySZRange): kk = range(ksz.min, ksz.max, ksz.mod)
  elif isinstance(ksz, C.KeySZAny): kk = range(64); sel = [0]
  kk = list(kk); kk = kk[:]
  n = len(kk)
  while n and len(sel) < 4:
    i = R.range(n)
    n -= 1
    kk[i], kk[n] = kk[n], kk[i]
    sel.append(kk[n])
  return sel

def pad0star(m, w):
  n = len(m)
  if not n: r = w
  else: r = (-len(m))%w
  if r: m += Z(r)
  return C.ByteString(m)

def pad10star(m, w):
  r = w - len(m)%w
  if r: m += '\x80' + Z(r - 1)
  return C.ByteString(m)

def ntz(i):
  j = 0
  while (i&1) == 0: i >>= 1; j += 1
  return j

def blocks(x, w):
  v, i, n = [], 0, len(x)
  while n - i > w:
    v.append(C.ByteString(x[i:i + w]))
    i += w
  return v, C.ByteString(x[i:])

EMPTY = C.bytes('')

def blocks0(x, w):
  v, tl = blocks(x, w)
  if len(tl) == w: v.append(tl); tl = EMPTY
  return v, tl

def dummygen(bc): return []

CUSTOM = {}

###--------------------------------------------------------------------------
### RC6.

class RC6Cipher (type):
  def __new__(cls, w, r):
    name = 'rc6-%d/%d' % (w, r)
    me = type(name, (RC6Base,), {})
    me.name = name
    me.r = r
    me.w = w
    me.blksz = w/2
    me.keysz = C.KeySZRange(me.blksz, 1, 255, 1)
    return me

def rotw(w):
  return w.bit_length() - 1

def rol(w, x, n):
  m0, m1 = C.MP(0).setbit(w - n) - 1, C.MP(0).setbit(n) - 1
  return ((x&m0) << n) | (x >> (w - n))&m1

def ror(w, x, n):
  m0, m1 = C.MP(0).setbit(n) - 1, C.MP(0).setbit(w - n) - 1
  return ((x&m0) << (w - n)) | (x >> n)&m1

class RC6Base (object):

  ## Magic constants.
  P400 = C.MP(0xb7e151628aed2a6abf7158809cf4f3c762e7160f38b4da56a784d9045190cfef324e7738926cfbe5f4bf8d8d8c31d763da06)
  Q400 = C.MP(0x9e3779b97f4a7c15f39cc0605cedc8341082276bf3a27251f86c6a11d0c18e952767f0b153d27b7f0347045b5bf1827f0188)

  def __init__(me, k):

    ## Build the magic numbers.
    P = me.P400 >> (400 - me.w)
    if P%2 == 0: P += 1
    Q = me.Q400 >> (400 - me.w)
    if Q%2 == 0: Q += 1
    M = C.MP(0).setbit(me.w) - 1

    ## Convert the key into words.
    wb = me.w/8
    c = (len(k) + wb - 1)/wb
    kb, ktl = blocks(k, me.w/8)
    L = map(C.MP.loadl, kb + [ktl])
    assert c == len(L)

    ## Build the subkey table.
    me.d = rotw(me.w)
    n = 2*me.r + 4
    S = [(P + i*Q)&M for i in xrange(n)]

    ##for j in xrange(c):
    ##  print 'L[%3d] = %s' % (j, hex(L[j]).upper()[2:].rjust(2*wb, '0'))
    ##for i in xrange(n):
    ##  print 'S[%3d] = %s' % (i, hex(S[i]).upper()[2:].rjust(2*wb, '0'))

    i = j = 0
    A = B = C.MP(0)

    for s in xrange(3*max(c, n)):
      A = S[i] = rol(me.w, S[i] + A + B, 3)
      B = L[j] = rol(me.w, L[j] + A + B, (A + B)%(1 << me.d))
      ##print 'S[%3d] = %s' % (i, hex(S[i]).upper()[2:].rjust(2*wb, '0'))
      ##print 'L[%3d] = %s' % (j, hex(L[j]).upper()[2:].rjust(2*wb, '0'))
      i = (i + 1)%n
      j = (j + 1)%c

    ## Done.
    me.s = S

  def encrypt(me, x):
    M = C.MP(0).setbit(me.w) - 1
    a, b, c, d = map(C.MP.loadl, blocks0(x, me.blksz/4)[0])
    b = (b + me.s[0])&M
    d = (d + me.s[1])&M
    ##print 'B = %s' % (hex(b).upper()[2:].rjust(me.w/4, '0'))
    ##print 'D = %s' % (hex(d).upper()[2:].rjust(me.w/4, '0'))
    for i in xrange(2, 2*me.r + 2, 2):
      t = rol(me.w, 2*b*b + b, me.d)
      u = rol(me.w, 2*d*d + d, me.d)
      a = (rol(me.w, a ^ t, u%(1 << me.d)) + me.s[i + 0])&M
      c = (rol(me.w, c ^ u, t%(1 << me.d)) + me.s[i + 1])&M
      ##print 'A = %s' % (hex(a).upper()[2:].rjust(me.w/4, '0'))
      ##print 'C = %s' % (hex(c).upper()[2:].rjust(me.w/4, '0'))
      a, b, c, d = b, c, d, a
    a = (a + me.s[2*me.r + 2])&M
    c = (c + me.s[2*me.r + 3])&M
    ##print 'A = %s' % (hex(a).upper()[2:].rjust(me.w/4, '0'))
    ##print 'C = %s' % (hex(c).upper()[2:].rjust(me.w/4, '0'))
    return C.ByteString(a.storel(me.blksz/4) + b.storel(me.blksz/4) +
                        c.storel(me.blksz/4) + d.storel(me.blksz/4))

  def decrypt(me, x):
    M = C.MP(0).setbit(me.w) - 1
    a, b, c, d = map(C.MP.loadl, blocks0(x, me.blksz/4))
    c = (c - me.s[2*me.r + 3])&M
    a = (a - me.s[2*me.r + 2])&M
    for i in xrange(2*me.r + 1, 1, -2):
      a, b, c, d = d, a, b, c
      u = rol(me.w, 2*d*d + d, me.d)
      t = rol(me.w, 2*b*b + b, me.d)
      c = ror(me.w, (c - me.s[i + 1])&M, t%(1 << me.d)) ^ u
      a = ror(me.w, (a - me.s[i + 0])&M, u%(1 << me.d)) ^ t
    a = (a + s[2*me.r + 2])&M
    c = (c + s[2*me.r + 3])&M
    return C.ByteString(a.storel(me.blksz/4) + b.storel(me.blksz/4) +
                        c.storel(me.blksz/4) + d.storel(me.blksz/4))

for (w, r) in [(8, 16), (16, 16), (24, 16), (32, 16),
               (32, 20), (48, 16), (64, 16), (96, 16), (128, 16),
               (192, 16), (256, 16), (400, 16)]:
  CUSTOM['rc6-%d/%d' % (w, r)] = RC6Cipher(w, r)

###--------------------------------------------------------------------------
### OMAC (or CMAC).

def omac_masks(E):
  blksz = E.__class__.blksz
  p = poly(8*blksz)
  z = Z(blksz)
  L = E.encrypt(z)
  m0 = mul_blk_gf(L, 2, p)
  m1 = mul_blk_gf(m0, 2, p)
  return m0, m1

def dump_omac(E):
  blksz = E.__class__.blksz
  m0, m1 = omac_masks(E)
  print 'L = %s' % hex(E.encrypt(Z(blksz)))
  print 'm0 = %s' % hex(m0)
  print 'm1 = %s' % hex(m1)
  for t in xrange(3):
    print 'v%d = %s' % (t, hex(E.encrypt(C.MP(t).storeb(blksz))))
    print 'z%d = %s' % (t, hex(omac(E, t, '')))

def omac(E, t, m):
  blksz = E.__class__.blksz
  m0, m1 = omac_masks(E)
  a = Z(blksz)
  if t is not None: m = C.MP(t).storeb(blksz) + m
  v, tl = blocks(m, blksz)
  for x in v: a = E.encrypt(a ^ x)
  r = blksz - len(tl)
  if r == 0:
    a = E.encrypt(a ^ tl ^ m0)
  else:
    pad = pad10star(tl, blksz)
    a = E.encrypt(a ^ pad ^ m1)
  return a

def cmac(E, m):
  if VERBOSE: dump_omac(E)
  return omac(E, None, m),

def cmacgen(bc):
  return [(0,), (1,),
          (3*bc.blksz,),
          (3*bc.blksz - 5,)]

###--------------------------------------------------------------------------
### Counter mode.

def ctr(E, m, c0):
  blksz = E.__class__.blksz
  y = C.WriteBuffer()
  c = C.MP.loadb(c0)
  while y.size < len(m):
    y.put(E.encrypt(c.storeb(blksz)))
    c += 1
  return C.ByteString(m) ^ C.ByteString(y)[:len(m)]

###--------------------------------------------------------------------------
### EAX.

def eaxenc(E, n, h, m, tsz = None):
  if VERBOSE:
    print 'k = %s' % hex(k)
    print 'n = %s' % hex(n)
    print 'h = %s' % hex(h)
    print 'm = %s' % hex(m)
    dump_omac(E)
  if tsz is None: tsz = E.__class__.blksz
  c0 = omac(E, 0, n)
  y = ctr(E, m, c0)
  ht = omac(E, 1, h)
  yt = omac(E, 2, y)
  if VERBOSE:
    print 'c0 = %s' % hex(c0)
    print 'ht = %s' % hex(ht)
    print 'yt = %s' % hex(yt)
  return y, C.ByteString((c0 ^ ht ^ yt)[:tsz])

def eaxdec(E, n, h, y, t):
  if VERBOSE:
    print 'k = %s' % hex(k)
    print 'n = %s' % hex(n)
    print 'h = %s' % hex(h)
    print 'y = %s' % hex(y)
    print 't = %s' % hex(t)
    dump_omac(E)
  c0 = omac(E, 0, n)
  m = ctr(E, y, c0)
  ht = omac(E, 1, h)
  yt = omac(E, 2, y)
  if VERBOSE:
    print 'c0 = %s' % hex(c0)
    print 'ht = %s' % hex(ht)
    print 'yt = %s' % hex(yt)
  if t == (c0 ^ ht ^ yt)[:len(t)]: return m,
  else: return None,

def eaxgen(bc):
  return [(0, 0, 0), (1, 0, 0), (0, 1, 0), (0, 0, 1),
          (bc.blksz, 3*bc.blksz, 3*bc.blksz),
          (bc.blksz - 1, 3*bc.blksz - 5, 3*bc.blksz + 5)]

###--------------------------------------------------------------------------
### Main program.

class struct (object):
  def __init__(me, **kw):
    me.__dict__.update(kw)

binarg = struct(mk = R.block, parse = C.bytes, show = safehex)
intarg = struct(mk = lambda x: x, parse = int, show = None)

MODEMAP = { 'eax-enc': (eaxgen, 3*[binarg] + [intarg], eaxenc),
            'eax-dec': (dummygen, 4*[binarg], eaxdec),
            'cmac': (cmacgen, [binarg], cmac) }

mode = argv[1]
bc = None
for d in CUSTOM, C.gcprps:
  try: bc = d[argv[2]]
  except KeyError: pass
  else: break
if bc is None: raise KeyError, argv[2]
if len(argv) == 3:
  VERBOSE = False
  gen, argty, func = MODEMAP[mode]
  if mode.endswith('-enc'): mode = mode[:-4]
  print '%s-%s {' % (bc.name, mode)
  for ksz in keylens(bc.keysz):
    for argvals in gen(bc):
      k = R.block(ksz)
      args = [t.mk(a) for t, a in izip(argty, argvals)]
      rets = func(bc(k), *args)
      print '  %s' % safehex(k)
      for t, a in izip(argty, args):
        if t.show: print '    %s' % t.show(a)
      for r, lastp in with_lastp(rets):
        print '    %s%s' % (safehex(r), lastp and ';' or '')
  print '}'
else:
  VERBOSE = True
  k = C.bytes(argv[3])
  gen, argty, func = MODEMAP[mode]
  args = [t.parse(a) for t, a in izip(argty, argv[4:])]
  rets = func(bc(k), *args)
  for r in rets:
    if r is None: print "X"
    else: print hex(r)

###----- That's all, folks --------------------------------------------------