feat(bn) add from_mpi, to_mpi and set API

fffonion · Dec 19, 2023 · 086f5b0 · 086f5b0
1 parent 253d11c
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diff --git a/README.md b/README.md
@@ -74,7 +74,9 @@ Table of Contents
     + [bn.new](#bnnew)
     + [bn.dup](#bndup)
     + [bn.istype](#bnistype)
+    + [bn:set](#bnset)
     + [bn.from_binary, bn:to_binary](#bnfrom_binary-bnto_binary)
+    + [bn.from_mpi, bn:to_mpi](#bnfrom_mpi-bnto_mpi)
     + [bn.from_hex, bn:to_hex](#bnfrom_hex-bnto_hex)
     + [bn.from_dec, bn:to_dec](#bnfrom_dec-bnto_dec)
     + [bn:to_number](#bnto_number)
@@ -1380,8 +1382,20 @@ Module to expose BIGNUM structure. Note bignum is a big integer, no float operat
 
 **syntax**: *b, err = bn.new(number?)*
 
-Creates a `bn` instance. The first argument can be a Lua number or `nil` to
-creates an empty instance.
+**syntax**: *b, err = bn.new(string?, base?)*
+
+Creates a `bn` instance. The first argument can be:
+
+- `nil` to creates an empty bn instance.
+- A Lua number to initialize the bn instance.
+- A string to initialize the bn instance. The second argument `base` specifies the base of the string,
+and can take value from (compatible with Ruby OpenSSL.BN API):
+  - `10` or omitted, for decimal string (`"23333"`)
+  - `16`, for hex encoded string (`"5b25"`)
+  - `2`, for binary string (`"\x5b\x25"`)
+  - `0`, for MPI formated string (`"\x00\x00\x00\x02\x5b\x25"`)
+
+MPI is a format that consists of the number's length in bytes represented as a 4-byte big-endian number, and the number itself in big-endian format, where the most significant bit signals a negative number (the representation of numbers with the MSB set is prefixed with null byte).
 
 [Back to TOC](#table-of-contents)
 
@@ -1401,6 +1415,17 @@ Returns `true` if table is an instance of `bn`. Returns `false` otherwise.
 
 [Back to TOC](#table-of-contents)
 
+### bn.set
+
+**syntax**: *b, err = bn:set(number)*
+
+**syntax**: *b, err = bn:set(string, base?)*
+
+Reuse the existing bn instance and reset its value with given number or string.
+Refer to [bn.new](#bnnew) for the type of arguments supported.
+
+[Back to TOC](#table-of-contents)
+
 ### bn.from_binary, bn:to_binary
 
 **syntax**: *bn, err = bn.from_binary(bin)*
@@ -1415,10 +1440,32 @@ Exports the BIGNUM value in binary string.
 used to pad leading zeros to the output to a specific length.
 
 ```lua
-local b, err = require("resty.openssl.bn").from_binary(ngx.decode_base64("WyU="))
+local to_hex = require "resty.string".to_hex
+local b, err = require("resty.openssl.bn").from_binary("\x5b\x25")
 local bin, err = b:to_binary()
-ngx.say(ngx.encode_base64(bin))
--- outputs "WyU="
+ngx.say(to_hex(bin))
+-- outputs "5b25
+```
+
+[Back to TOC](#table-of-contents)
+
+### bn.from_mpi, bn:to_mpi
+
+**syntax**: *bn, err = bn.from_mpi(bin)*
+
+**syntax**: *bin, err = bn:to_mpi()*
+
+Creates a `bn` instance from MPI formatted binary string.
+
+Exports the BIGNUM value in MPI formatted binary string.
+
+
+```lua
+local to_hex = require "resty.string".to_hex
+local b, err = require("resty.openssl.bn").from_mpi("\x00\x00\x00\x02\x5b\x25")
+local bin, err = b:to_mpi()
+ngx.say(to_hex(bin))
+-- outputs "000000025b25
 ```
 
 [Back to TOC](#table-of-contents)

diff --git a/lib/resty/openssl/bn.lua b/lib/resty/openssl/bn.lua
@@ -9,24 +9,80 @@ require "resty.openssl.include.bn"
 local crypto_macro = require("resty.openssl.include.crypto")
 local ctypes = require "resty.openssl.auxiliary.ctypes"
 local format_error = require("resty.openssl.err").format_error
-local OPENSSL_3X = require("resty.openssl.version").OPENSSL_3X
 
 local _M = {}
 local mt = {__index = _M}
 
 local bn_ptr_ct = ffi.typeof('BIGNUM*')
 local bn_ptrptr_ct = ffi.typeof('BIGNUM*[1]')
 
-function _M.new(bn)
+local function set_binary(ctx, s)
+  local ctx = C.BN_bin2bn(s, #s, ctx)
+  if ctx == nil then
+    return nil, format_error("set_binary")
+  end
+  return ctx
+end
+
+local function set_mpi(ctx, s)
+  local ctx = C.BN_mpi2bn(s, #s, ctx)
+  if ctx == nil then
+    return nil, format_error("set_mpi")
+  end
+  return ctx
+end
+
+local function set_hex(ctx, s)
+  local p = ffi_new(bn_ptrptr_ct)
+  p[0] = ctx
+
+  if C.BN_hex2bn(p, s) == 0 then
+    return nil, format_error("set_hex")
+  end
+  return p[0]
+end
+
+local function set_dec(ctx, s)
+  local p = ffi_new(bn_ptrptr_ct)
+  p[0] = ctx
+
+  if C.BN_dec2bn(p, s) == 0 then
+    return nil, format_error("set_dec")
+  end
+  return p[0]
+end
+
+local function set_bn(ctx, s, base)
+  if type(s) == 'number' then
+    if C.BN_set_word(ctx, s) ~= 1 then
+      return nil, format_error("set_bn")
+    end
+  elseif type(s) == 'string' then
+    if not base or base == 10 then
+      return set_dec(ctx, s)
+    elseif base == 16 then
+      return set_hex(ctx, s)
+    elseif base == 2 then
+      return set_binary(ctx, s)
+    elseif base == 0 then
+      ctx = set_mpi(ctx, s)
+    else
+      return nil, "set_bn: unsupported base: " .. base
+    end
+  elseif s then
+    return nil, "set_bn: expect nil, a number or a string at #1"
+  end
+
+  return ctx
+end
+
+function _M.new(some, base)
   local ctx = C.BN_new()
   ffi_gc(ctx, C.BN_free)
 
-  if type(bn) == 'number' then
-    if C.BN_set_word(ctx, bn) ~= 1 then
-      return nil, format_error("bn.new")
-    end
-  elseif bn then
-    return nil, "bn.new: expect nil or a number at #1"
+  local ctx, err = set_bn(ctx, some, base)
+  if err then
+    return nil, "bn.new: " .. err
   end
 
   return setmetatable( { ctx = ctx }, mt), nil
@@ -50,6 +106,19 @@ function _M.dup(ctx)
   return self
 end
 
+function _M:set(some, base)
+  if not some then
+    return nil, "expect a number or a string at #1"
+  end
+
+  local _, err = set_bn(self.ctx, some, base)
+  if err then
+    return nil, "bn:set: " .. err
+  end
+
+  return self
+end
+
 function _M:to_binary(pad)
   if pad then
     if type(pad) ~= "number" then
@@ -80,17 +149,22 @@ function _M:to_binary(pad)
   return ffi_str(buf, sz)
 end
 
-function _M.from_binary(s)
-  if type(s) ~= "string" then
-    return nil, "bn.from_binary: expect a string at #1"
+function _M:to_mpi(no_header)
+  local length = C.BN_bn2mpi(self.ctx, nil)
+  if length <= 0 then
+    return nil, format_error("bn:to_mpi")
   end
 
-  local ctx = C.BN_bin2bn(s, #s, nil)
-  if ctx == nil then
-    return nil, format_error("bn.from_binary")
+  local buf = ctypes.uchar_array(length)
+
+  local sz = C.BN_bn2mpi(self.ctx, buf)
+  if sz <= 0 then
+    return nil, format_error("bn:to_mpi")
   end
-  ffi_gc(ctx, C.BN_free)
-  return setmetatable( { ctx = ctx }, mt), nil
+
+  local ret = ffi_str(buf, sz)
+
+  return no_header and ret:sub(4) or ret
 end
 
 function _M:to_hex()
@@ -103,21 +177,6 @@ function _M:to_hex()
   return s
 end
 
-function _M.from_hex(s)
-  if type(s) ~= "string" then
-    return nil, "bn.from_hex: expect a string at #1"
-  end
-
-  local p = ffi_new(bn_ptrptr_ct)
-
-  if C.BN_hex2bn(p, s) == 0 then
-    return nil, format_error("bn.from_hex")
-  end
-  local ctx = p[0]
-  ffi_gc(ctx, C.BN_free)
-  return setmetatable( { ctx = ctx }, mt), nil
-end
-
 function _M:to_dec()
   local buf = C.BN_bn2dec(self.ctx)
   if buf == nil then
@@ -129,26 +188,35 @@ function _M:to_dec()
 end
 mt.__tostring = _M.to_dec
 
-function _M.from_dec(s)
-  if type(s) ~= "string" then
-    return nil, "bn.from_dec: expect a string at #1"
-  end
-
-  local p = ffi_new(bn_ptrptr_ct)
-
-  if C.BN_dec2bn(p, s) == 0 then
-    return nil, format_error("bn.from_dec")
-  end
-  local ctx = p[0]
-  ffi_gc(ctx, C.BN_free)
-  return setmetatable( { ctx = ctx }, mt), nil
-end
-
 function _M:to_number()
   return tonumber(C.BN_get_word(self.ctx))
 end
 _M.tonumber = _M.to_number
 
+local from_funcs = {
+  binary = set_binary,
+  mpi = set_mpi,
+  hex = set_hex,
+  dec = set_dec,
+}
+
+for typ, func in pairs(from_funcs) do
+  local sig = "from_" .. typ
+  _M[sig] = function(s)
+    if type(s) ~= "string" then
+      return nil, "bn." .. sig .. ": expect a string at #1"
+    end
+
+    local ctx, err = func(nil, s)
+    if not ctx then
+      return nil, "bn." .. sig .. ": " .. err
+    end
+
+    ffi_gc(ctx, C.BN_free)
+    return setmetatable( { ctx = ctx }, mt), nil
+  end
+end
+
 function _M.generate_prime(bits, safe)
   local ctx = C.BN_new()
   ffi_gc(ctx, C.BN_free)
@@ -373,12 +441,7 @@ function _M:is_prime(nchecks)
   end
   -- if nchecks is not defined, set to BN_prime_checks:
   -- select number of iterations based on the size of the number
-  local code
-  if OPENSSL_3X then
-    code = C.BN_check_prime(self.ctx, bn_ctx_tmp, nil)
-  else
-    code = C.BN_is_prime_ex(self.ctx, nchecks or 0, bn_ctx_tmp, nil)
-  end
+  local code = C.BN_is_prime_ex(self.ctx, nchecks or 0, bn_ctx_tmp, nil)
   if code == -1 then
     return nil, format_error("bn.is_prime")
   end

diff --git a/lib/resty/openssl/include/bn.lua b/lib/resty/openssl/include/bn.lua
@@ -1,7 +1,6 @@
 local ffi = require "ffi"
 
 require "resty.openssl.include.ossl_typ"
-local OPENSSL_3X = require("resty.openssl.version").OPENSSL_3X
 
 local BN_ULONG
 if ffi.abi('64bit') then
@@ -33,6 +32,9 @@ ffi.cdef(
   char *BN_bn2hex(const BIGNUM *a);
   char *BN_bn2dec(const BIGNUM *a);
 
+  int BN_bn2mpi(const BIGNUM *a, unsigned char *to);
+  BIGNUM *BN_mpi2bn(const unsigned char *s, int len, BIGNUM *ret);
+
   void BN_set_negative(BIGNUM *a, int n);
   int  BN_is_negative(const BIGNUM *a);
 
@@ -60,7 +62,6 @@ ffi.cdef(
   int BN_cmp(BIGNUM *a, BIGNUM *b);
   int BN_ucmp(BIGNUM *a, BIGNUM *b);
 
-  // openssl >= 1.1 only
   int BN_is_zero(BIGNUM *a);
   int BN_is_one(BIGNUM *a);
   int BN_is_word(BIGNUM *a, ]] .. BN_ULONG ..[[ w);
@@ -70,10 +71,4 @@ ffi.cdef(
   int BN_generate_prime_ex(BIGNUM *ret,int bits,int safe, const BIGNUM *add,
                             const BIGNUM *rem, BN_GENCB *cb);
 ]]
-)
-
-if OPENSSL_3X then
-  ffi.cdef [[
-    int BN_check_prime(const BIGNUM *p, BN_CTX *ctx, BN_GENCB *cb);
-  ]]
-end
+)