if p.irreduciblep(): POLYMAP[nbits] = p; return p
raise ValueError, nbits
+def prim(nbits):
+ ## No fancy way to do this: I'd need a much cleverer factoring algorithm
+ ## than I have in my pockets.
+ if nbits == 64: cc = [64, 4, 3, 1, 0]
+ elif nbits == 96: cc = [96, 10, 9, 6, 0]
+ elif nbits == 128: cc = [128, 7, 2, 1, 0]
+ elif nbits == 192: cc = [192, 15, 11, 5, 0]
+ elif nbits == 256: cc = [256, 10, 5, 2, 0]
+ else: raise ValueError, 'no field for %d bits' % nbits
+ p = C.GF(0)
+ for c in cc: p = p.setbit(c)
+ return p
+
def Z(n):
return C.ByteString.zero(n)
(bc.blksz - 1, 3*bc.blksz - 5, 3*bc.blksz + 5)]
###--------------------------------------------------------------------------
+### PMAC.
+
+def ocb_masks(E):
+ blksz = E.__class__.blksz
+ p = poly(8*blksz)
+ x = C.GF(2); xinv = p.modinv(x)
+ z = Z(blksz)
+ L = E.encrypt(z)
+ Lxinv = mul_blk_gf(L, xinv, p)
+ Lgamma = 66*[L]
+ for i in xrange(1, len(Lgamma)):
+ Lgamma[i] = mul_blk_gf(Lgamma[i - 1], x, p)
+ return Lgamma, Lxinv
+
+def dump_ocb(E):
+ Lgamma, Lxinv = ocb_masks(E)
+ print 'L x^-1 = %s' % hex(Lxinv)
+ for i, lg in enumerate(Lgamma[:16]):
+ print 'L x^%d = %s' % (i, hex(lg))
+
+def pmac1(E, m):
+ blksz = E.__class__.blksz
+ Lgamma, Lxinv = ocb_masks(E)
+ a = o = Z(blksz)
+ i = 0
+ v, tl = blocks(m, blksz)
+ for x in v:
+ i += 1
+ b = ntz(i)
+ o ^= Lgamma[b]
+ a ^= E.encrypt(x ^ o)
+ if VERBOSE:
+ print 'Z[%d]: %d -> %s' % (i, b, hex(o))
+ print 'A[%d]: %s' % (i, hex(a))
+ if len(tl) == blksz: a ^= tl ^ Lxinv
+ else: a ^= pad10star(tl, blksz)
+ return E.encrypt(a)
+
+def pmac2(E, m):
+ blksz = E.__class__.blksz
+ p = prim(8*blksz)
+ L = E.encrypt(Z(blksz))
+ o = mul_blk_gf(L, 10, p)
+ a = Z(blksz)
+ v, tl = blocks(m, blksz)
+ for x in v:
+ a ^= E.encrypt(x ^ o)
+ o = mul_blk_gf(o, 2, p)
+ if len(tl) == blksz: a ^= tl ^ mul_blk_gf(o, 3, p)
+ else: a ^= pad10star(tl, blksz) ^ mul_blk_gf(o, 5, p)
+ return E.encrypt(a)
+
+def pmac1_pub(E, m):
+ if VERBOSE: dump_ocb(E)
+ return pmac1(E, m),
+
+def pmacgen(bc):
+ return [(0,), (1,),
+ (3*bc.blksz,),
+ (3*bc.blksz - 5,)]
+
+###--------------------------------------------------------------------------
+### OCB.
+
+def ocb1enc(E, n, h, m, tsz = None):
+ ## This is OCB1.PMAC1 from Rogaway's `Authenticated-Encryption with
+ ## Associated-Data'.
+ blksz = E.__class__.blksz
+ if VERBOSE: dump_ocb(E)
+ Lgamma, Lxinv = ocb_masks(E)
+ if tsz is None: tsz = blksz
+ a = Z(blksz)
+ o = E.encrypt(n ^ Lgamma[0])
+ if VERBOSE: print 'R = %s' % hex(o)
+ i = 0
+ y = C.WriteBuffer()
+ v, tl = blocks(m, blksz)
+ for x in v:
+ i += 1
+ b = ntz(i)
+ o ^= Lgamma[b]
+ a ^= x
+ if VERBOSE:
+ print 'Z[%d]: %d -> %s' % (i, b, hex(o))
+ print 'A[%d]: %s' % (i, hex(a))
+ y.put(E.encrypt(x ^ o) ^ o)
+ i += 1
+ b = ntz(i)
+ o ^= Lgamma[b]
+ n = len(tl)
+ if VERBOSE:
+ print 'Z[%d]: %d -> %s' % (i, b, hex(o))
+ print 'LEN = %s' % hex(C.MP(8*n).storeb(blksz))
+ yfinal = E.encrypt(C.MP(8*n).storeb(blksz) ^ Lxinv ^ o)
+ cfinal = tl ^ yfinal[:n]
+ a ^= o ^ (tl + yfinal[n:])
+ y.put(cfinal)
+ t = E.encrypt(a)
+ if h: t ^= pmac1(E, h)
+ return C.ByteString(y), C.ByteString(t[:tsz])
+
+def ocb1dec(E, n, h, y, t):
+ ## This is OCB1.PMAC1 from Rogaway's `Authenticated-Encryption with
+ ## Associated-Data'.
+ blksz = E.__class__.blksz
+ if VERBOSE: dump_ocb(E)
+ Lgamma, Lxinv = ocb_masks(E)
+ a = Z(blksz)
+ o = E.encrypt(n ^ Lgamma[0])
+ if VERBOSE: print 'R = %s' % hex(o)
+ i = 0
+ m = C.WriteBuffer()
+ v, tl = blocks(y, blksz)
+ for x in v:
+ i += 1
+ b = ntz(i)
+ o ^= Lgamma[b]
+ if VERBOSE:
+ print 'Z[%d]: %d -> %s' % (i, b, hex(o))
+ print 'A[%d]: %s' % (i, hex(a))
+ u = E.decrypt(x ^ o) ^ o
+ m.put(u)
+ a ^= u
+ i += 1
+ b = ntz(i)
+ o ^= Lgamma[b]
+ n = len(tl)
+ if VERBOSE:
+ print 'Z[%d]: %d -> %s' % (i, b, hex(o))
+ print 'LEN = %s' % hex(C.MP(8*n).storeb(blksz))
+ yfinal = E.encrypt(C.MP(8*n).storeb(blksz) ^ Lxinv ^ o)
+ mfinal = tl ^ yfinal[:n]
+ a ^= o ^ (mfinal + yfinal[n:])
+ m.put(mfinal)
+ u = E.encrypt(a)
+ if h: u ^= pmac1(E, h)
+ if t == u[:len(t)]: return C.ByteString(m),
+ else: return None,
+
+def ocb2enc(E, n, h, m, tsz = None):
+ ## For OCB2, it's important for security that n = log_x (x + 1) is large in
+ ## the field representations of GF(2^w) used -- in fact, we need more, that
+ ## i n (mod 2^w - 1) is large for i in {4, -3, -2, -1, 1, 2, 3, 4}. The
+ ## original paper lists the values for 64 and 128, but we support other
+ ## block sizes, so here's the result of the (rather large, in some cases)
+ ## computation.
+ ##
+ ## Block size log_x (x + 1)
+ ##
+ ## 64 9686038906114705801
+ ## 96 63214690573408919568138788065
+ ## 128 338793687469689340204974836150077311399
+ ## 192 161110085006042185925119981866940491651092686475226538785
+ ## 256 22928580326165511958494515843249267194111962539778797914076675796261938307298
+
+ blksz = E.__class__.blksz
+ if tsz is None: tsz = blksz
+ p = prim(8*blksz)
+ L = E.encrypt(n)
+ o = mul_blk_gf(L, 2, p)
+ a = Z(blksz)
+ v, tl = blocks(m, blksz)
+ y = C.WriteBuffer()
+ for x in v:
+ a ^= x
+ y.put(E.encrypt(x ^ o) ^ o)
+ o = mul_blk_gf(o, 2, p)
+ n = len(tl)
+ yfinal = E.encrypt(C.MP(8*n).storeb(blksz) ^ o)
+ cfinal = tl ^ yfinal[:n]
+ a ^= (tl + yfinal[n:]) ^ mul_blk_gf(o, 3, p)
+ y.put(cfinal)
+ t = E.encrypt(a)
+ if h: t ^= pmac2(E, h)
+ return C.ByteString(y), C.ByteString(t[:tsz])
+
+def ocb2dec(E, n, h, y, t):
+ blksz = E.__class__.blksz
+ p = prim(8*blksz)
+ L = E.encrypt(n)
+ o = mul_blk_gf(L, 2, p)
+ a = Z(blksz)
+ v, tl = blocks(y, blksz)
+ m = C.WriteBuffer()
+ for x in v:
+ u = E.encrypt(x ^ o) ^ o
+ y.put(u)
+ a ^= u
+ o = mul_blk_gf(o, 2, p)
+ n = len(tl)
+ yfinal = E.encrypt(C.MP(8*n).storeb(blksz) ^ o)
+ mfinal = tl ^ yfinal[:n]
+ a ^= (mfinal + yfinal[n:]) ^ mul_blk_gf(o, 3, p)
+ m.put(mfinal)
+ u = E.encrypt(a)
+ if h: u ^= pmac2(E, h)
+ if t == u[:len(t)]: return C.ByteString(m),
+ else: return None,
+
+def ocbgen(bc):
+ w = bc.blksz
+ return [(w, 0, 0), (w, 1, 0), (w, 0, 1),
+ (w, 0, 3*w),
+ (w, 3*w, 3*w),
+ (w, 0, 3*w + 5),
+ (w, 3*w - 5, 3*w + 5)]
+
+###--------------------------------------------------------------------------
### Main program.
class struct (object):
'ccm-dec': (dummygen, 4*[binarg], ccmdec),
'cmac': (cmacgen, [binarg], cmac),
'gcm-enc': (gcmgen, 3*[binarg] + [intarg], gcmenc),
- 'gcm-dec': (dummygen, 4*[binarg], gcmdec) }
+ 'gcm-dec': (dummygen, 4*[binarg], gcmdec),
+ 'ocb1-enc': (ocbgen, 3*[binarg] + [intarg], ocb1enc),
+ 'ocb1-dec': (dummygen, 4*[binarg], ocb1dec),
+ 'ocb2-enc': (ocbgen, 3*[binarg] + [intarg], ocb2enc),
+ 'ocb2-dec': (dummygen, 4*[binarg], ocb2dec),
+ 'pmac1': (pmacgen, [binarg], pmac1_pub) }
mode = argv[1]
bc = None
~mdw / catacomb / blobdiff