Implementation of Sapling in-band secret distribution.

src/zcash/NoteEncryption.hpp

@@ -10,12 +10,70 @@ https://github.com/zcash/zips/blob/master/protocol/protocol.pdf
 #include "uint252.h"
 
 #include "zcash/Zcash.h"
+#include "zcash/Address.hpp"
 
 #include <array>
 
 namespace libzcash {
 
-#define NOTEENCRYPTION_AUTH_BYTES 16
+// Ciphertext for the recipient to decrypt
+typedef std::array<unsigned char, ZC_SAPLING_ENCCIPHERTEXT_SIZE> SaplingEncCiphertext;
+typedef std::array<unsigned char, ZC_SAPLING_ENCPLAINTEXT_SIZE> SaplingEncPlaintext;
+
+// Ciphertext for outgoing viewing key to decrypt
+typedef std::array<unsigned char, ZC_SAPLING_OUTCIPHERTEXT_SIZE> SaplingOutCiphertext;
+typedef std::array<unsigned char, ZC_SAPLING_OUTPLAINTEXT_SIZE> SaplingOutPlaintext;
+
+class SaplingNoteEncryption {
+protected:
+    // Ephemeral public key
+    uint256 epk;
+
+    // Ephemeral secret key
+    uint256 esk;
+
+    SaplingNoteEncryption(uint256 epk, uint256 esk) : epk(epk), esk(esk) {
+
+    }
+
+public:
+
+    static boost::optional<SaplingNoteEncryption> FromDiversifier(diversifier_t d);
+
+    boost::optional<SaplingEncCiphertext> encrypt_to_recipient(
+        const uint256 &pk_d,
+        const SaplingEncPlaintext &message
+    );
+
+    SaplingOutCiphertext encrypt_to_ourselves(
+        const uint256 &ovk,
+        const uint256 &cv,
+        const uint256 &cm,
+        const SaplingOutPlaintext &message
+    );
+
+    uint256 get_epk() const {
+        return epk;
+    }
+};
+
+// Attempts to decrypt a Sapling note. This will not check that the contents
+// of the ciphertext are correct.
+boost::optional<SaplingEncPlaintext> AttemptSaplingEncDecryption(
+    const SaplingEncCiphertext &ciphertext,
+    const uint256 &ivk,
+    const uint256 &epk
+);
+
+// Attempts to decrypt a Sapling note. This will not check that the contents
+// of the ciphertext are correct.
+boost::optional<SaplingOutPlaintext> AttemptSaplingOutDecryption(
+    const SaplingOutCiphertext &ciphertext,
+    const uint256 &ovk,
+    const uint256 &cv,
+    const uint256 &cm,
+    const uint256 &epk
+);
 
 template<size_t MLEN>
 class NoteEncryption {