crypto: ecdsa - Add support for ECDSA signature verification

Add support for parsing the parameters of a NIST P256 or NIST P192 key.
Enable signature verification using these keys. The new module is
enabled with CONFIG_ECDSA:
  Elliptic Curve Digital Signature Algorithm (NIST P192, P256 etc.)
  is A NIST cryptographic standard algorithm. Only signature verification
  is implemented.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 25 insertions, 0 deletions

diff --git a/crypto/ecc.h b/crypto/ecc.h
index d4e546b9ad79..e0e2aed0557a 100644
--- a/crypto/ecc.h
+++ b/crypto/ecc.h
@@ -33,6 +33,8 @@
 
 #define ECC_DIGITS_TO_BYTES_SHIFT 3
 
+#define ECC_MAX_BYTES (ECC_MAX_DIGITS << ECC_DIGITS_TO_BYTES_SHIFT)
+
 /**
  * struct ecc_point - elliptic curve point in affine coordinates
  *
@@ -71,6 +73,29 @@ struct ecc_curve {
 };
 
 /**
+ * ecc_swap_digits() - Copy ndigits from big endian array to native array
+ * @in:       Input array
+ * @out:      Output array
+ * @ndigits:  Number of digits to copy
+ */
+static inline void ecc_swap_digits(const u64 *in, u64 *out, unsigned int ndigits)
+{
+	const __be64 *src = (__force __be64 *)in;
+	int i;
+
+	for (i = 0; i < ndigits; i++)
+		out[i] = be64_to_cpu(src[ndigits - 1 - i]);
+}
+
+/**
+ * ecc_get_curve()  - Get a curve given its curve_id
+ * @curve_id:  Id of the curve
+ *
+ * Returns pointer to the curve data, NULL if curve is not available
+ */
+const struct ecc_curve *ecc_get_curve(unsigned int curve_id);
+
+/**
  * ecc_is_key_valid() - Validate a given ECDH private key
  *
  * @curve_id:		id representing the curve to use