X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=secnet.git;a=blobdiff_plain;f=dh.c;h=c37b5386359294f856fb08eaf156a4c2ca586856;hp=fff9b998c54062eaa473968640f40acc6b6f8a5d;hb=abf665fc6ca2974e13acede83e0a77967fdccf9a;hpb=59230b9b9fc44453f24c6b3cf33a0f4c570a3563

diff --git a/dh.c b/dh.c
index fff9b99..c37b538 100644
--- a/dh.c
+++ b/dh.c
@@ -12,7 +12,7 @@ struct dh {
     MP_INT p,g; /* prime modulus and generator */
 };
 
-static string_t dh_makepublic(void *sst, uint8_t *secret, uint32_t secretlen)
+static string_t dh_makepublic(void *sst, uint8_t *secret, int32_t secretlen)
 {
     struct dh *st=sst;
     string_t r;
@@ -33,9 +33,9 @@ static string_t dh_makepublic(void *sst, uint8_t *secret, uint32_t secretlen)
 }
 
 static dh_makeshared_fn dh_makeshared;
-static void dh_makeshared(void *sst, uint8_t *secret, uint32_t secretlen,
+static void dh_makeshared(void *sst, uint8_t *secret, int32_t secretlen,
 			  cstring_t rempublic, uint8_t *sharedsecret,
-			  uint32_t buflen)
+			  int32_t buflen)
 {
     struct dh *st=sst;
     MP_INT a, b, c;
@@ -125,6 +125,10 @@ static list_t *dh_apply(closure_t *self, struct cloc loc, dict_t *context,
 
     st->ops.len=sz;
 
+    st->ops.ceil_len=(mpz_sizeinbase(&st->p,2)+7)/8;
+    /* According to the docs, mpz_sizeinbase(,256) is allowed to return
+     * an answer which is 1 too large.  But mpz_sizeinbase(,2) isn't. */
+
     return new_closure(&st->cl);
 }