+
+struct GNUNET_SENSOR_crypto_pow_context;
+
+/**
+ * Block carrying arbitrary data + its proof-of-work + signature
+ */
+struct GNUNET_SENSOR_crypto_pow_block
+{
+
+ /**
+ * Proof-of-work value
+ */
+ uint64_t pow;
+
+ /**
+ * Data signature
+ */
+ struct GNUNET_CRYPTO_EddsaSignature signature;
+
+ /**
+ * Size of the msg component (allocated after this struct)
+ */
+ size_t msg_size;
+
+ /**
+ * Purpose of signing.
+ * Data is allocated after this (timestamp, public_key, msg).
+ */
+ struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
+
+ /**
+ * First part of data - timestamp
+ */
+ struct GNUNET_TIME_Absolute timestamp;
+
+ /**
+ * Second part of data - Public key
+ */
+ struct GNUNET_CRYPTO_EddsaPublicKey public_key;
+
+};
+
+
+/**
+ * Continuation called with a status result.
+ *
+ * @param cls closure
+ * @param pow Proof-of-work value
+ * @param purpose Signed block (size, purpose, data)
+ * @param signature Signature, NULL on error
+ */
+typedef void (*GNUNET_SENSOR_UTIL_pow_callback) (void *cls,
+ struct
+ GNUNET_SENSOR_crypto_pow_block
+ * block);
+
+
+/**
+ * Cancel an operation started by #GNUNET_SENSOR_crypto_pow_sign().
+ * Call only before callback function passed to #GNUNET_SENSOR_crypto_pow_sign()
+ * is called with the result.
+ */
+void
+GNUNET_SENSOR_crypto_pow_sign_cancel (struct GNUNET_SENSOR_crypto_pow_context
+ *cx);
+
+
+/**
+ * Calculate proof-of-work and sign a message.
+ *
+ * @param msg Message to calculate pow and sign
+ * @param msg_size size of msg
+ * @param timestamp Timestamp to add to the message to protect against replay attacks
+ * @param public_key Public key of the origin peer, to protect against redirect attacks
+ * @param private_key Private key of the origin peer to sign the result
+ * @param matching_bits Number of leading zeros required in the result hash
+ * @param callback Callback function to call with the result
+ * @param callback_cls Closure for callback
+ * @return Operation context
+ */
+struct GNUNET_SENSOR_crypto_pow_context *
+GNUNET_SENSOR_crypto_pow_sign (void *msg, size_t msg_size,
+ struct GNUNET_TIME_Absolute *timestamp,
+ struct GNUNET_CRYPTO_EddsaPublicKey *public_key,
+ struct GNUNET_CRYPTO_EddsaPrivateKey
+ *private_key, int matching_bits,
+ GNUNET_SENSOR_UTIL_pow_callback callback,
+ void *callback_cls);
+
+
+/**
+ * Verify that proof-of-work and signature in the given block are valid.
+ * If all valid, a pointer to the payload within the block is set and the size
+ * of the payload is returned.
+ *
+ * **VERY IMPORTANT** : You will still need to verify the timestamp yourself.
+ *
+ * @param block The block received and needs to be verified
+ * @param matching_bits Number of leading zeros in the hash used to verify pow
+ * @param public_key Public key of the peer that sent this block
+ * @param payload Where to store the pointer to the payload
+ * @return Size of the payload
+ */
+size_t
+GNUNET_SENSOR_crypto_verify_pow_sign (struct GNUNET_SENSOR_crypto_pow_block *
+ block, int matching_bits,
+ struct GNUNET_CRYPTO_EddsaPublicKey *
+ public_key, void **payload);
+
+