pkg/libcose: add RIOT as crypto backend

pkg/libcose/Kconfig

@@ -31,6 +31,11 @@ config MODULE_LIBCOSE_CRYPT_MONOCYPHER
     depends on TEST_KCONFIG
     depends on PACKAGE_MONOCYPHER
 
+config MODULE_LIBCOSE_CRYPT_RIOT
+    bool "COSE use RIOT backend"
+    depends on TEST_KCONFIG
+    select MODULE_CRYPTO
+
 config MODULE_LIBCOSE_CRYPT_INIT
     bool "LibCose Crypt Initialization functions"
     default y

pkg/libcose/Makefile.dep

@@ -16,6 +16,9 @@ endif
 ifneq (,$(filter libcose_crypt_monocypher,$(USEMODULE)))
   USEPKG += monocypher
 endif
+ifneq (,$(filter libcose_crypt_riot,$(USEMODULE)))
+  USEMODULE += crypto
+endif
 
-DEFAULT_MODULE += auto_init_libcose_crypt
 DEFAULT_MODULE += libcose_crypt_init
+DEFAULT_MODULE += auto_init_libcose_crypt

pkg/libcose/Makefile.include

@@ -1,4 +1,7 @@
-INCLUDES += -I$(PKGDIRBASE)/libcose/include
+INCLUDES += -I$(PKGDIRBASE)/libcose/include \
+            -I$(RIOTBASE)/pkg/libcose/include \
+            #
+
 CFLAGS += -DUSE_CBOR_CONTEXT
 
 ifneq (,$(filter libcose_crypt_hacl,$(USEMODULE)))
@@ -13,6 +16,10 @@ endif
 ifneq (,$(filter libcose_crypt_monocypher,$(USEMODULE)))
   CFLAGS += -DCRYPTO_MONOCYPHER
 endif
+ifneq (,$(filter libcose_crypt_riot,$(USEMODULE)))
+  CFLAGS += -DCRYPTO_RIOT
+  DIRS += $(RIOTBASE)/pkg/libcose/contrib
+endif
 ifneq (,$(filter libcose_crypt_init,$(USEMODULE)))
   DIRS += $(RIOTBASE)/pkg/libcose/init
 endif

pkg/libcose/contrib/libcose_riot_crypto.c

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2022 Inria
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     pkg_libcose
+ * @{
+ *
+ * @file
+ * @brief       RIOT as a crypto backend for libcose implementation
+ *
+ * @author      Francisco Molina <francois-xavier.molina@inria.fr>
+ *
+ * @}
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "crypto/chacha20poly1305.h"
+
+#include "cose.h"
+#include "cose/crypto.h"
+#include "cose/crypto/selectors.h"
+
+int cose_crypto_aead_encrypt_chachapoly(uint8_t *c, size_t *clen,
+                                        const uint8_t *msg, size_t msglen,
+                                        const uint8_t *aad, size_t aadlen,
+                                        const uint8_t *npub, const uint8_t *k)
+{
+    if (*clen < msglen + CHACHA20POLY1305_TAG_BYTES) {
+        return COSE_ERR_INVALID_PARAM;
+    }
+    chacha20poly1305_encrypt(c, msg, msglen, aad, aadlen, k, npub);
+    *clen = msglen + CHACHA20POLY1305_TAG_BYTES;
+    return COSE_OK;
+}
+
+int cose_crypto_aead_decrypt_chachapoly(uint8_t *msg, size_t *msglen,
+                                        const uint8_t *c, size_t clen,
+                                        const uint8_t *aad, size_t aadlen,
+                                        const uint8_t *npub, const uint8_t *k)
+{
+    if (chacha20poly1305_decrypt(c, clen, msg, msglen, aad, aadlen, k, npub) == 1) {
+        return COSE_OK;
+    }
+    else {
+        return COSE_ERR_CRYPTO;
+    }
+}

pkg/libcose/include/cose/crypto/riot.h

@@ -31,6 +31,14 @@ extern "C" {
 #define AUTO_INIT_PRIO_MOD_LIBCOSE                      1050
 #endif
 
+/**
+ * @name list of provided algorithms
+ *
+ * @{
+ */
+#define HAVE_ALGO_CHACHA20POLY1305
+/** @} */
+
 /**
  * @brief   Initialize libCOSE RIOT crypto backend
  *