Add ElligatorSwift key creation and ECDH logic

Co-authored-by: Dhruv Mehta <856960+dhruv@users.noreply.github.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/pubkey.cpp b/src/pubkey.cpp
index ae5dccfb5a..4866feed67 100644
--- a/src/pubkey.cpp
+++ b/src/pubkey.cpp
@@ -7,6 +7,7 @@
 
 #include <hash.h>
 #include <secp256k1.h>
+#include <secp256k1_ellswift.h>
 #include <secp256k1_extrakeys.h>
 #include <secp256k1_recovery.h>
 #include <secp256k1_schnorrsig.h>
@@ -335,6 +336,20 @@ bool CPubKey::Derive(CPubKey& pubkeyChild, ChainCode &ccChild, unsigned int nChi
     return true;
 }
 
+CPubKey EllSwiftPubKey::Decode() const
+{
+    secp256k1_pubkey pubkey;
+    secp256k1_ellswift_decode(secp256k1_context_static, &pubkey, UCharCast(m_pubkey.data()));
+
+    size_t sz = CPubKey::COMPRESSED_SIZE;
+    std::array<uint8_t, CPubKey::COMPRESSED_SIZE> vch_bytes;
+
+    secp256k1_ec_pubkey_serialize(secp256k1_context_static, vch_bytes.data(), &sz, &pubkey, SECP256K1_EC_COMPRESSED);
+    assert(sz == vch_bytes.size());
+
+    return CPubKey{vch_bytes.begin(), vch_bytes.end()};
+}
+
 void CExtPubKey::Encode(unsigned char code[BIP32_EXTKEY_SIZE]) const {
     code[0] = nDepth;
     memcpy(code+1, vchFingerprint, 4);