1 files changed, 67 insertions, 0 deletions
diff --git a/fticks.c b/fticks.c
new file mode 100644
index 0000000..ab750a3
--- /dev/null
+++ b/fticks.c
@@ -0,0 +1,67 @@
+/* Copyright (C) 2011 NORDUnet A/S
+ * See LICENSE for information about licensing.
+ */
+
+#include <stdio.h>		/* For sprintf().  */
+#include <string.h>
+#include <nettle/sha.h>
+#include <nettle/hmac.h>
+
+static void
+format_hash(const uint8_t *hash, size_t out_len, uint8_t *out)
+{
+    int i;
+
+    for (i = 0; i < out_len / 2; i++)
+	sprintf((char *) out + i*2, "%02x", hash[i % SHA256_DIGEST_SIZE]);
+}
+
+static void
+hash(const uint8_t *in,
+     const uint8_t *key,
+     size_t out_len,
+     uint8_t *out)
+{
+    if (key == NULL) {
+	struct sha256_ctx ctx;
+	uint8_t hash[SHA256_DIGEST_SIZE];
+
+	sha256_init(&ctx);
+	sha256_update(&ctx, strlen((char *) in), in);
+	sha256_digest(&ctx, sizeof(hash), hash);
+	format_hash(hash, out_len, out);
+    }
+    else {
+	struct hmac_sha256_ctx ctx;
+	uint8_t hash[SHA256_DIGEST_SIZE];
+
+	hmac_sha256_set_key(&ctx, strlen((char *) key), key);
+	hmac_sha256_update(&ctx, strlen((char *) in), in);
+	hmac_sha256_digest(&ctx, sizeof(hash), hash);
+	format_hash(hash, out_len, out);
+    }
+}
+
+/** Hash the MAC in \a IN, keying with \a KEY if it's not NULL.
+
+    \a IN and \a KEY are NULL terminated strings.
+
+    \a IN is sanitised by lowercasing it, removing all but [0-9a-f]
+    and truncating it at first ';' (due to RADIUS praxis with tacking
+    on SSID to MAC in Calling-Station-Id).  */
+void
+fticks_hashmac(const uint8_t *in,
+	       const uint8_t *key,
+	       size_t out_len,
+	       uint8_t *out)
+{
+    /* TODO: lowercase */
+    /* TODO: s/[!0-9a-f]//1 */
+    /* TODO: truncate after first ';', if any */
+
+    hash(in, key, out_len, out);
+}
+
+/* Local Variables: */
+/* c-file-style: "stroustrup" */
+/* End: */