Merge branch 'beta' into mergemaster

# Conflicts:
#	src/main.cpp

src/secp256k1/include/secp256k1_ecdh.h

@@ -0,0 +1,31 @@
+#ifndef SECP256K1_ECDH_H
+#define SECP256K1_ECDH_H
+
+#include "secp256k1.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Compute an EC Diffie-Hellman secret in constant time
+ *  Returns: 1: exponentiation was successful
+ *           0: scalar was invalid (zero or overflow)
+ *  Args:    ctx:        pointer to a context object (cannot be NULL)
+ *  Out:     result:     a 32-byte array which will be populated by an ECDH
+ *                       secret computed from the point and scalar
+ *  In:      pubkey:     a pointer to a secp256k1_pubkey containing an
+ *                       initialized public key
+ *           privkey:    a 32-byte scalar with which to multiply the point
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdh(
+  const secp256k1_context* ctx,
+  unsigned char *result,
+  const secp256k1_pubkey *pubkey,
+  const unsigned char *privkey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SECP256K1_ECDH_H */