1 files changed, 77 insertions, 0 deletions
diff --git a/firmware/2lib/2packed_key.c b/firmware/2lib/2packed_key.c
new file mode 100644
index 00000000..fe6bab53
--- /dev/null
+++ b/firmware/2lib/2packed_key.c
@@ -0,0 +1,77 @@
+/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Key unpacking functions
+ */
+
+#include "2sysincludes.h"
+#include "2common.h"
+#include "2rsa.h"
+
+const uint8_t *vb2_packed_key_data(const struct vb2_packed_key *key)
+{
+	return (const uint8_t *)key + key->key_offset;
+}
+
+int vb2_verify_packed_key_inside(const void *parent,
+				 uint32_t parent_size,
+				 const struct vb2_packed_key *key)
+{
+	return vb2_verify_member_inside(parent, parent_size,
+					key, sizeof(*key),
+					key->key_offset, key->key_size);
+}
+
+int vb2_unpack_key(struct vb2_public_key *key,
+		   const uint8_t *buf,
+		   uint32_t size)
+{
+	const struct vb2_packed_key *packed_key =
+		(const struct vb2_packed_key *)buf;
+	const uint32_t *buf32;
+	uint32_t expected_key_size;
+	int rv;
+
+	/* Make sure passed buffer is big enough for the packed key */
+	rv = vb2_verify_packed_key_inside(buf, size, packed_key);
+	if (rv)
+		return rv;
+
+	/* Unpack key algorithm */
+	key->sig_alg = vb2_crypto_to_signature(packed_key->algorithm);
+	if (key->sig_alg == VB2_SIG_INVALID) {
+		VB2_DEBUG("Unsupported signature algorithm.\n");
+		return VB2_ERROR_UNPACK_KEY_SIG_ALGORITHM;
+	}
+
+	key->hash_alg = vb2_crypto_to_hash(packed_key->algorithm);
+	if (key->hash_alg == VB2_HASH_INVALID) {
+		VB2_DEBUG("Unsupported hash algorithm.\n");
+		return VB2_ERROR_UNPACK_KEY_HASH_ALGORITHM;
+	}
+
+	expected_key_size = vb2_packed_key_size(key->sig_alg);
+	if (!expected_key_size || expected_key_size != packed_key->key_size) {
+		VB2_DEBUG("Wrong key size for algorithm\n");
+		return VB2_ERROR_UNPACK_KEY_SIZE;
+	}
+
+	/* Make sure source buffer is 32-bit aligned */
+	buf32 = (const uint32_t *)vb2_packed_key_data(packed_key);
+	if (!vb_aligned(buf32, sizeof(uint32_t)))
+		return VB2_ERROR_UNPACK_KEY_ALIGN;
+
+	/* Sanity check key array size */
+	key->arrsize = buf32[0];
+	if (key->arrsize * sizeof(uint32_t) != vb2_rsa_sig_size(key->sig_alg))
+		return VB2_ERROR_UNPACK_KEY_ARRAY_SIZE;
+
+	key->n0inv = buf32[1];
+
+	/* Arrays point inside the key data */
+	key->n = buf32 + 2;
+	key->rr = buf32 + 2 + key->arrsize;
+
+	return VB2_SUCCESS;
+}