build, lib, ipcpd, irmd: Add support for libgcrypt

This adds support for libgcrypt. If at least version 1.7.0 of
libgcrypt is present, it may be used for secure random number
generation and is used for hashing in the irmd/ipcp.

The hash definitions are moved to the internal hash.h header, and
defined independently of the hashes that are defined as part of the
directory policy for the normal IPCP. The translation is moved from
the IRMd to ipcpd/ipcp.h. The bootstrap call from the IRMd expects the
IPCP to return the correct hash algorithm with a dif_info struct,
which is in line with the behavior of the enroll call.

This also improves how some platform checks in the build system are
handled.

1 files changed, 7 insertions, 10 deletions

diff --git a/include/ouroboros/ipcp.h b/include/ouroboros/ipcp.h
index 1b775a63..7c34cc7d 100644
--- a/include/ouroboros/ipcp.h
+++ b/include/ouroboros/ipcp.h
@@ -52,22 +52,19 @@ enum pol_routing {
         LINK_STATE = 0
 };
 
-/* Hash algorithms */
-enum hash_algo {
-        HASH_CRC32 = 0,
-        HASH_MD5,
-        HASH_SHA3_224,
-        HASH_SHA3_256,
-        HASH_SHA3_384,
-        HASH_SHA3_512
+enum pol_dir_hash {
+        DIR_HASH_SHA3_224 = 0,
+        DIR_HASH_SHA3_256,
+        DIR_HASH_SHA3_384,
+        DIR_HASH_SHA3_512
 };
 
 #define DIF_NAME_SIZE 256
 
 /* Info reported back to the IRMd about the DIF on enrollment */
 struct dif_info {
-        char           dif_name[DIF_NAME_SIZE];
-        enum hash_algo dir_hash_algo;
+        char              dif_name[DIF_NAME_SIZE];
+        enum pol_dir_hash dir_hash_algo;
 };
 
 /* Structure to configure the first IPCP */