Use 'generator' parameter for picking generator for DH keys (rather than 'exp'). Change default value to 2.

2 is the default generator for openssl; the number is a mostly arbitrary choice, and smaller values are faster.

3 files changed, 9 insertions, 5 deletions

diff --git a/doc/luaossl.pdf b/doc/luaossl.pdf
index 81142cb..81112d9 100644
--- a/doc/luaossl.pdf
+++ b/doc/luaossl.pdf
diff --git a/doc/luaossl.tex b/doc/luaossl.tex
index 7bb85df..5ac7761 100644
--- a/doc/luaossl.tex
+++ b/doc/luaossl.tex
@@ -284,7 +284,9 @@ field & type:default & description\\\hline
 
 .bits & number:1024 & private key size \\
 
-.exp & number:65537 & RSA or Diffie-Hellman exponent \\
+.exp & number:65537 & RSA exponent \\
+
+.generator & number:2 & Diffie-Hellman generator \\
 
 .dhparam & string & PEM encoded string with precomputed DH parameters \\
 
diff --git a/src/openssl.c b/src/openssl.c
index 0760c35..0354666 100644
--- a/src/openssl.c
+++ b/src/openssl.c
@@ -3212,6 +3212,7 @@ static int pk_new(lua_State *L) {
                 int type = EVP_PKEY_RSA;
                 unsigned bits = 1024;
                 unsigned exp = 65537;
+                int generator = 2;
                 int curve = NID_X9_62_prime192v1;
                 const char *id;
                 const char *dhparam = NULL;
@@ -3264,9 +3265,10 @@ static int pk_new(lua_State *L) {
                                 bits = (unsigned)n;
                         }
 
-                        if (loadfield(L, 1, "exp", LUA_TNUMBER, &n)) {
-                                luaL_argcheck(L, n > 0 && n < UINT_MAX, 1, lua_pushfstring(L, "%f: `exp' invalid", n));
-                                exp = (unsigned)n;
+                        /* compat: DH used to use the 'exp' field for the generator */
+                        if (loadfield(L, 1, "generator", LUA_TNUMBER, &n) || loadfield(L, 1, "exp", LUA_TNUMBER, &n)) {
+                                luaL_argcheck(L, n > 0 && n <= INT_MAX, 1, lua_pushfstring(L, "%f: `exp' invalid", n));
+                                generator = (int)n;
                         }
                         break;
                 case EVP_PKEY_EC:
@@ -3327,7 +3329,7 @@ creat:
                                 BIO_free(bio);
                                 if (!dh)
                                         return auxL_error(L, auxL_EOPENSSL, "pkey.new");
-                        } else if (!(dh = DH_generate_parameters(bits, exp, 0, 0)))
+                        } else if (!(dh = DH_generate_parameters(bits, generator, 0, 0)))
                                 return auxL_error(L, auxL_EOPENSSL, "pkey.new");