Re: [PATCH 3/5] lib: ecdsa: Implement signature verification for crypto_algo API

Hi,

On 1/11/21 4:41 PM, Alexandru Gagniuc wrote:

Implement the crypto_algo .verify() function for ecdsa256. Because it backends on UCLASS_ECDSA, this change is focused on parsing the keys from devicetree and passing this information to the specific UCLASS driver.

Signed-off-by: Alexandru Gagniucmr.nuke.me@gmail.com

lib/ecdsa/ecdsa-verify.c | 117 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 116 insertions(+), 1 deletion(-)

diff --git a/lib/ecdsa/ecdsa-verify.c b/lib/ecdsa/ecdsa-verify.c index d2e6a40f4a..d84f6eb093 100644 --- a/lib/ecdsa/ecdsa-verify.c +++ b/lib/ecdsa/ecdsa-verify.c @@ -1,13 +1,128 @@ // SPDX-License-Identifier: GPL-2.0+ /*

• • ECDSA signature verification for u-boot
• • This implements the firmware-side wrapper for ECDSA verification. It bridges
• • the struct crypto_algo API to the ECDSA uclass implementations.
• • Copyright (c) 2020, Alexandru Gagniucmr.nuke.me@gmail.com
  */

http://www.denx.de/wiki/U-Boot/CodingStyle #Include files

#include <crypto/ecdsa-uclass.h>

it is normally the first in alphabetic order of directory

+#include <dm/uclass.h> #include <u-boot/ecdsa.h> +#include <crypto/ecdsa-uclass.h>

+/*

• • Derive size of an ECDSA key from the curve name
• • While it's possible to extract the key size by using string manipulation,
• • use a list of known curves for the time being.
• */

+static int ecdsa_key_size(const char *curve_name) +{

• if (!strcmp(curve_name, "prime256v1"))

• return 256;
  

• else

• return 0;
  

+}

To prepare the future can you parse a array of supported curves with associated ID

used as parameter of ECDSA parameter = enum ECDSA_CURVES

for example: char * name, int size, enum ECDSA_CURVES

const [] = { {"prime256v1", 256, ECDSA_PRIME256V1 },

}

+static int fdt_get_key(struct ecdsa_public_key *key, const void *fdt, int node) +{

• int x_len, y_len;
• key->curve_name = fdt_getprop(fdt, node, "ecdsa,curve", NULL);
• key->size_bits = ecdsa_key_size(key->curve_name);
• if (key->size_bits == 0) {

• debug("Unknown ECDSA curve '%s'", key->curve_name);
  

• return -EINVAL;
  

• }
• key->x = fdt_getprop(fdt, node, "ecdsa,x-point", &x_len);
• key->y = fdt_getprop(fdt, node, "ecdsa,y-point", &y_len);
• if (!key->x || !key->y)

• return -EINVAL;
  

• if (x_len != (key->size_bits / 8) || y_len != (key->size_bits / 8)) {

• printf("%s: node=%d, curve@%p x@%p+%i y@%p+%i\n", __func__,
  

•        node, key->curve_name, key->x, x_len, key->y, y_len);
  

• return -EINVAL;
  

• }
• return 0;

+}

+static int ecdsa_verify_hash(struct udevice *dev,

• 	     const struct image_sign_info *info,
  

• 	     const void *hash, const void *sig, uint sig_len)
  

+{

• const struct ecdsa_ops *ops = device_get_ops(dev);
• const struct checksum_algo *algo = info->checksum;
• struct ecdsa_public_key key;
• int sig_node, key_node, ret;
• if (!ops || !ops->verify)

• return -ENODEV;
  

• if (info->required_keynode > 0) {

• ret = fdt_get_key(&key, info->fdt_blob, info->required_keynode);
  

• if (ret < 0)
  

• 	return ret;
  

• return ops->verify(dev, &key, hash, algo->checksum_len,
  

• 		   sig, sig_len);
  

Need to indicate the used curve here as parameter of the verify opts ?

• }
• sig_node = fdt_subnode_offset(info->fdt_blob, 0, FIT_SIG_NODENAME);
• if (sig_node < 0)

• return -ENOENT;
  

• /* Try all possible keys under the "/signature" node */
• fdt_for_each_subnode(key_node, info->fdt_blob, sig_node) {

• ret = fdt_get_key(&key, info->fdt_blob, key_node);
  

• if (ret < 0)
  

• 	continue;
  

• ret = ops->verify(dev, &key, hash, algo->checksum_len,
  

• 		  sig, sig_len);
  

• /* On success, don't worry about remaining keys */
  

• if (ret == 0)
  

issue raised by chekpatch I think

if (!ret)

• 	return 0;
  

• }
• return -EPERM;

+}

int ecdsa_verify(struct image_sign_info *info, const struct image_region region[], int region_count, uint8_t *sig, uint sig_len) {

• return -EOPNOTSUPP;

• const struct checksum_algo *algo = info->checksum;
• uint8_t hash[algo->checksum_len];
• struct udevice *dev;
• int ret;
• ret = uclass_first_device(UCLASS_ECDSA, &dev);
• if (ret) {

• debug("ECDSA: Could not find ECDSA implementation: %d\n", ret);
  

• return ret;
  

• }
• ret = algo->calculate(algo->name, region, region_count, hash);
• if (ret < 0)

• return -EINVAL;
  

• return ecdsa_verify_hash(dev, info, hash, sig, sig_len); }

+/*

• • uclass definition for ECDSA API
• • We don't implement any wrappers around ecdsa_ops->verify() because it's
• • trivial to call ops->verify().
• */

+UCLASS_DRIVER(ecdsa) = {

• .id = UCLASS_ECDSA,
• .name = "ecdsa_verifier",

+};

Regards

Patrick