Automatically calculate RSA a, b, c, see #11.

lib/resty/nettle/mpz.lua

@@ -16,6 +16,9 @@ size_t __gmpz_sizeinbase(const mpz_t op, int base);
 char * __gmpz_get_str(char *str, int base, const mpz_t op);
 int __gmpz_set_str(mpz_t rop, const char *str, int base);
 void __gmpz_set_ui(mpz_t, unsigned long int iv);
+int __gmpz_invert(mpz_ptr, mpz_srcptr, mpz_srcptr);
+void __gmpz_sub_ui(mpz_ptr, mpz_srcptr, unsigned long int);
+void __gmpz_fdiv_r(mpz_ptr, mpz_srcptr, mpz_srcptr);
 ]]
 
 local ctx = ffi_typeof "mpz_t"
@@ -60,4 +63,16 @@ function mpz.set(op, value, base)
  return true
 end
 
+function mpz.invert(rop, op1, op2)
+ return gmp.__gmpz_invert(rop, op1, op2)
+end
+
+function mpz.sub(rop, op1, op2)
+ gmp.__gmpz_sub_ui(rop, op1, op2)
+end
+
+function mpz.div(rop, op1, op2)
+ gmp.__gmpz_fdiv_r(rop, op1, op2)
+end
+
 return mpz

lib/resty/nettle/rsa.lua

@@ -106,35 +106,55 @@ function private.new(d, p, q, a, b, c, base)
  return nil, err
  end
  end
+ local p1
  if p then
  local ok, err = mpz.set(context[0].p, p, base)
  if not ok then
  return nil, err
  end
+ if d and not a then
+ p1 = mpz.new()
+ mpz.sub(p1, context[0].p, 1)
+ end
  end
+ local q1
  if q then
  local ok, err = mpz.set(context[0].q, q, base)
  if not ok then
  return nil, err
  end
+ if d and not b then
+ q1 = mpz.new()
+ mpz.sub(q1, context[0].q, 1)
+ end
  end
  if a then
  local ok, err = mpz.set(context[0].a, a, base)
  if not ok then
  return nil, err
  end
+ elseif p1 then
+ mpz.div(context[0].a, context[0].d, p1)
  end
  if b then
  local ok, err = mpz.set(context[0].b, b, base)
  if not ok then
  return nil, err
  end
+ elseif q1 then
+ mpz.div(context[0].b, context[0].d, q1)
  end
+
  if c then
  local ok, err = mpz.set(context[0].c, c, base)
  if not ok then
  return nil, err
  end
+ elseif q and p then
+ local ret = mpz.invert(context[0].c, context[0].q, context[0].p)
+ if ret == 0 then
+ ret = mpz.invert(context[0].c, context[0].q, context[0].p)
+ end
  end
  if d or p or q or a or b or c then
  if hogweed.nettle_rsa_private_key_prepare(context) ~= 1 then

lib/resty/nettle/types/mpz.lua

@@ -8,6 +8,7 @@ typedef struct {
  int _mp_size;
  mp_limb_t *_mp_d;
 } __mpz_struct;
+typedef const __mpz_struct *mpz_srcptr;
 typedef __mpz_struct mpz_t[1];
 typedef __mpz_struct *mpz_ptr;
 ]]