rsa: add sha256-rsa2048 algorithm

based on patch from andreas@oetken.name:

http://patchwork.ozlabs.org/patch/294318/
commit message:
I currently need support for rsa-sha256 signatures in u-boot and found out that
the code for signatures is not very generic. Thus adding of different
hash-algorithms for rsa-signatures is not easy to do without copy-pasting the
rsa-code. I attached a patch for how I think it could be better and included
support for rsa-sha256. This is a fast first shot.

aditionally work:
- removed checkpatch warnings
- removed compiler warnings
- rebased against current head

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: andreas@oetken.name
Cc: Simon Glass <sjg@chromium.org>

3 files changed, 58 insertions, 0 deletions

diff --git a/include/image.h b/include/image.h
index 52969aa..44b2b46 100644
--- a/include/image.h
+++ b/include/image.h
@@ -833,6 +833,7 @@ int calculate_hash(const void *data, int data_len, const char *algo,
 # ifdef USE_HOSTCC
 #  define IMAGE_ENABLE_SIGN	1
 #  define IMAGE_ENABLE_VERIFY	0
+# include  <openssl/evp.h>
 #else
 #  define IMAGE_ENABLE_SIGN	0
 #  define IMAGE_ENABLE_VERIFY	1
@@ -872,6 +873,23 @@ struct image_region {
 	int size;
 };
 
+#if IMAGE_ENABLE_VERIFY
+# include <rsa-checksum.h>
+#endif
+struct checksum_algo {
+	const char *name;
+	const int checksum_len;
+#if IMAGE_ENABLE_SIGN
+	const EVP_MD *(*calculate)(void);
+#else
+#if IMAGE_ENABLE_VERIFY
+	void (*calculate)(const struct image_region region[],
+			  int region_count, uint8_t *checksum);
+	const uint8_t *rsa_padding;
+#endif
+#endif
+};
+
 struct image_sig_algo {
 	const char *name;		/* Name of algorithm */
 
@@ -922,6 +940,9 @@ struct image_sig_algo {
 	int (*verify)(struct image_sign_info *info,
 		      const struct image_region region[], int region_count,
 		      uint8_t *sig, uint sig_len);
+
+	/* pointer to checksum algorithm */
+	struct checksum_algo *checksum;
 };
 
 /**
diff --git a/include/rsa-checksum.h b/include/rsa-checksum.h
new file mode 100644
index 0000000..850b253
--- /dev/null
+++ b/include/rsa-checksum.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2013, Andreas Oetken.
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+*/
+
+#ifndef _RSA_CHECKSUM_H
+#define _RSA_CHECKSUM_H
+
+#include <errno.h>
+#include <image.h>
+#include <sha1.h>
+#include <sha256.h>
+
+extern const uint8_t padding_sha256_rsa2048[];
+extern const uint8_t padding_sha1_rsa2048[];
+
+void sha256_calculate(const struct image_region region[], int region_count,
+		      uint8_t *checksum);
+void sha1_calculate(const struct image_region region[], int region_count,
+		    uint8_t *checksum);
+
+#endif
diff --git a/include/rsa.h b/include/rsa.h
index add4c78..e9ae870 100644
--- a/include/rsa.h
+++ b/include/rsa.h
@@ -15,6 +15,20 @@
 #include <errno.h>
 #include <image.h>
 
+/**
+ * struct rsa_public_key - holder for a public key
+ *
+ * An RSA public key consists of a modulus (typically called N), the inverse
+ * and R^2, where R is 2^(# key bits).
+ */
+
+struct rsa_public_key {
+	uint len;		/* len of modulus[] in number of uint32_t */
+	uint32_t n0inv;		/* -1 / modulus[0] mod 2^32 */
+	uint32_t *modulus;	/* modulus as little endian array */
+	uint32_t *rr;		/* R^2 as little endian array */
+};
+
 #if IMAGE_ENABLE_SIGN
 /**
  * sign() - calculate and return signature for given input data