[PATCH] kdf: Allow empty password for Argon2

[Milan Broz]

* cipher/kdf.c (_gcry_kdf_open) allow empty password for Argon2.
--

This patch fixes libcryptsetup requirement to support empty
passwords for PBKDF (and passes Argon2 test vectors there now).

Signed-off-by: Milan Broz <gmazyland at gmail.com>
---
 cipher/kdf.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/cipher/kdf.c b/cipher/kdf.c
index d371bdd7..3e51e115 100644
--- a/cipher/kdf.c
+++ b/cipher/kdf.c
@@ -402,10 +402,13 @@ argon2_fill_first_blocks (argon2_ctx_t a)
   iov[iov_count].len = 4 * 7;
   iov[iov_count].off = 0;
   iov_count++;
-  iov[iov_count].data = (void *)a->password;
-  iov[iov_count].len = a->passwordlen;
-  iov[iov_count].off = 0;
-  iov_count++;
+  if (a->passwordlen)
+    {
+      iov[iov_count].data = (void *)a->password;
+      iov[iov_count].len = a->passwordlen;
+      iov[iov_count].off = 0;
+      iov_count++;
+    }
 
   buf_put_le32 (buf[7], a->saltlen);
   iov[iov_count].data = buf[7];
@@ -1861,7 +1864,7 @@ _gcry_kdf_open (gcry_kdf_hd_t *hd, int algo, int subalgo,
   switch (algo)
     {
     case GCRY_KDF_ARGON2:
-      if (!inputlen || !saltlen)
+      if (!saltlen)
         ec = GPG_ERR_INV_VALUE;
       else
         ec = argon2_open (hd, subalgo, param, paramlen,
-- 
2.36.1