[PATCH 1/5] dm: crypto: Define UCLASS API for ECDSA signature verification

[Alexandru Gagniuc <mr.nuke.me@gmail.com>]

Define a UCLASS API for verifying ECDSA signatures. Unlike
UCLASS_MOD_EXP, which focuses strictly on modular exponentiation,
the ECDSA class focuses on verification. This is done so that it
better aligns with mach-specific implementations, such as stm32mp.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
---
 include/crypto/ecdsa-uclass.h | 39 +++++++++++++++++++++++++++++++++++
 include/dm/uclass-id.h        |  1 +
 2 files changed, 40 insertions(+)
 create mode 100644 include/crypto/ecdsa-uclass.h

diff --git a/include/crypto/ecdsa-uclass.h b/include/crypto/ecdsa-uclass.h
new file mode 100644
index 0000000000..189843820a
--- /dev/null
+++ b/include/crypto/ecdsa-uclass.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2020, Alexandru Gagniuc <mr.nuke.me@gmail.com>
+ */
+
+#include <dm/device.h>
+
+/**
+ * struct ecdsa_public_key - ECDSA public key properties
+ *
+ * The struct has pointers to the (x, y) curve coordinates to an ECDSA public
+ * key, as well as the name of the ECDSA curve. The size of the key is inferred
+ * from the 'curve_name'
+ */
+struct ecdsa_public_key {
+	const char *curve_name;	/* Name of curve, e.g. "prime256v1" */
+	const void *x;		/* x coordinate of public key */
+	const void *y;		/* y coordinate of public key */
+	unsigned int size_bits;	/* key size in bits, derived from curve name */
+};
+
+struct ecdsa_ops {
+	/**
+	 * Verify signature of hash against given public key
+	 *
+	 * @dev:	ECDSA Device
+	 * @pubkey:	ECDSA public key
+	 * @hash:	Hash of binary image
+	 * @hash_len:	Length of hash in bytes
+	 * @signature:	Signature in a raw (R, S) point pair
+	 * @sig_len:	Length of signature in bytes
+	 *
+	 * This function verifies that the 'signature' of the given 'hash' was
+	 * signed by the private key corresponding to 'pubkey'.
+	 */
+	int (*verify)(struct udevice *dev, const struct ecdsa_public_key *pubkey,
+		      const void *hash, size_t hash_len,
+		      const void *signature, size_t sig_len);
+};
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index e952a9967c..de4f5db086 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -45,6 +45,7 @@ enum uclass_id {
 	UCLASS_DISPLAY,		/* Display (e.g. DisplayPort, HDMI) */
 	UCLASS_DSI_HOST,	/* Display Serial Interface host */
 	UCLASS_DMA,		/* Direct Memory Access */
+	UCLASS_ECDSA,		/* Elliptic curve cryptographic device */
 	UCLASS_EFI,		/* EFI managed devices */
 	UCLASS_ETH,		/* Ethernet device */
 	UCLASS_ETH_PHY,		/* Ethernet PHY device */
-- 
2.26.2