diff --git a/quartz/src/androidMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.android.kt b/quartz/src/androidMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.android.kt
new file mode 100644
index 0000000000..789fe2404a
--- /dev/null
+++ b/quartz/src/androidMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.android.kt
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.utils
+
+import fr.acinq.secp256k1.Secp256k1
+
+actual object Secp256k1Instance {
+    private val h02 = Hex.decode("02")
+    private val secp256k1 = Secp256k1.get()
+
+    actual fun compressedPubKeyFor(privKey: ByteArray) = secp256k1.pubKeyCompress(secp256k1.pubkeyCreate(privKey))
+
+    actual fun isPrivateKeyValid(il: ByteArray): Boolean = secp256k1.secKeyVerify(il)
+
+    actual fun signSchnorr(
+        data: ByteArray,
+        privKey: ByteArray,
+        nonce: ByteArray?,
+    ): ByteArray = secp256k1.signSchnorr(data, privKey, nonce)
+
+    actual fun signSchnorr(
+        data: ByteArray,
+        privKey: ByteArray,
+    ): ByteArray = secp256k1.signSchnorr(data, privKey, null)
+
+    actual fun verifySchnorr(
+        signature: ByteArray,
+        hash: ByteArray,
+        pubKey: ByteArray,
+    ): Boolean = secp256k1.verifySchnorr(signature, hash, pubKey)
+
+    actual fun privateKeyAdd(
+        first: ByteArray,
+        second: ByteArray,
+    ): ByteArray = secp256k1.privKeyTweakAdd(first, second)
+
+    actual fun pubKeyTweakMulCompact(
+        pubKey: ByteArray,
+        privateKey: ByteArray,
+    ): ByteArray = secp256k1.pubKeyTweakMul(h02 + pubKey, privateKey).copyOfRange(1, 33)
+}
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.kt
index c99652f366..594b025f94 100644
--- a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.kt
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.kt
@@ -20,47 +20,35 @@
  */
 package com.vitorpamplona.quartz.utils
 
-import com.vitorpamplona.quartz.utils.secp256k1.Secp256k1
+expect object Secp256k1Instance {
+    fun compressedPubKeyFor(privKey: ByteArray): ByteArray
 
-object Secp256k1Instance {
-    private val h02 = Hex.decode("02")
-
-    fun compressedPubKeyFor(privKey: ByteArray) = Secp256k1.pubKeyCompress(Secp256k1.pubkeyCreate(privKey))
-
-    fun isPrivateKeyValid(il: ByteArray): Boolean = Secp256k1.secKeyVerify(il)
+    fun isPrivateKeyValid(il: ByteArray): Boolean
 
     fun signSchnorr(
         data: ByteArray,
         privKey: ByteArray,
         nonce: ByteArray? = RandomInstance.bytes(32),
-    ): ByteArray = Secp256k1.signSchnorr(data, privKey, nonce)
+    ): ByteArray
 
     fun signSchnorr(
         data: ByteArray,
         privKey: ByteArray,
-    ): ByteArray = Secp256k1.signSchnorr(data, privKey, null)
-
-    /** Fast signing with pre-computed compressed public key (skips G multiplication). */
-    fun signSchnorrWithPubKey(
-        data: ByteArray,
-        privKey: ByteArray,
-        compressedPubKey: ByteArray,
-        nonce: ByteArray? = RandomInstance.bytes(32),
-    ): ByteArray = Secp256k1.signSchnorrWithPubKey(data, privKey, compressedPubKey, nonce)
+    ): ByteArray
 
     fun verifySchnorr(
         signature: ByteArray,
         hash: ByteArray,
         pubKey: ByteArray,
-    ): Boolean = Secp256k1.verifySchnorr(signature, hash, pubKey)
+    ): Boolean
 
     fun privateKeyAdd(
         first: ByteArray,
         second: ByteArray,
-    ): ByteArray = Secp256k1.privKeyTweakAdd(first, second)
+    ): ByteArray
 
     fun pubKeyTweakMulCompact(
         pubKey: ByteArray,
         privateKey: ByteArray,
-    ): ByteArray = Secp256k1.ecdhXOnly(pubKey, privateKey)
+    ): ByteArray
 }
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1InstanceOurs.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1InstanceOurs.kt
new file mode 100644
index 0000000000..145de46756
--- /dev/null
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1InstanceOurs.kt
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.utils
+
+import com.vitorpamplona.quartz.utils.secp256k1.Secp256k1
+
+object Secp256k1InstanceOurs {
+    private val h02 = Hex.decode("02")
+
+    fun compressedPubKeyFor(privKey: ByteArray) = Secp256k1.pubKeyCompress(Secp256k1.pubkeyCreate(privKey))
+
+    fun isPrivateKeyValid(il: ByteArray): Boolean = Secp256k1.secKeyVerify(il)
+
+    fun signSchnorr(
+        data: ByteArray,
+        privKey: ByteArray,
+        nonce: ByteArray? = RandomInstance.bytes(32),
+    ): ByteArray = Secp256k1.signSchnorr(data, privKey, nonce)
+
+    fun signSchnorr(
+        data: ByteArray,
+        privKey: ByteArray,
+    ): ByteArray = Secp256k1.signSchnorr(data, privKey, null)
+
+    /** Fast signing with pre-computed compressed public key (skips G multiplication). */
+    fun signSchnorrWithPubKey(
+        data: ByteArray,
+        privKey: ByteArray,
+        compressedPubKey: ByteArray,
+        nonce: ByteArray? = RandomInstance.bytes(32),
+    ): ByteArray = Secp256k1.signSchnorrWithPubKey(data, privKey, compressedPubKey, nonce)
+
+    fun verifySchnorr(
+        signature: ByteArray,
+        hash: ByteArray,
+        pubKey: ByteArray,
+    ): Boolean = Secp256k1.verifySchnorr(signature, hash, pubKey)
+
+    fun privateKeyAdd(
+        first: ByteArray,
+        second: ByteArray,
+    ): ByteArray = Secp256k1.privKeyTweakAdd(first, second)
+
+    fun pubKeyTweakMulCompact(
+        pubKey: ByteArray,
+        privateKey: ByteArray,
+    ): ByteArray = Secp256k1.ecdhXOnly(pubKey, privateKey)
+}
diff --git a/quartz/src/jvmMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.jvm.kt b/quartz/src/jvmMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.jvm.kt
new file mode 100644
index 0000000000..789fe2404a
--- /dev/null
+++ b/quartz/src/jvmMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.jvm.kt
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.utils
+
+import fr.acinq.secp256k1.Secp256k1
+
+actual object Secp256k1Instance {
+    private val h02 = Hex.decode("02")
+    private val secp256k1 = Secp256k1.get()
+
+    actual fun compressedPubKeyFor(privKey: ByteArray) = secp256k1.pubKeyCompress(secp256k1.pubkeyCreate(privKey))
+
+    actual fun isPrivateKeyValid(il: ByteArray): Boolean = secp256k1.secKeyVerify(il)
+
+    actual fun signSchnorr(
+        data: ByteArray,
+        privKey: ByteArray,
+        nonce: ByteArray?,
+    ): ByteArray = secp256k1.signSchnorr(data, privKey, nonce)
+
+    actual fun signSchnorr(
+        data: ByteArray,
+        privKey: ByteArray,
+    ): ByteArray = secp256k1.signSchnorr(data, privKey, null)
+
+    actual fun verifySchnorr(
+        signature: ByteArray,
+        hash: ByteArray,
+        pubKey: ByteArray,
+    ): Boolean = secp256k1.verifySchnorr(signature, hash, pubKey)
+
+    actual fun privateKeyAdd(
+        first: ByteArray,
+        second: ByteArray,
+    ): ByteArray = secp256k1.privKeyTweakAdd(first, second)
+
+    actual fun pubKeyTweakMulCompact(
+        pubKey: ByteArray,
+        privateKey: ByteArray,
+    ): ByteArray = secp256k1.pubKeyTweakMul(h02 + pubKey, privateKey).copyOfRange(1, 33)
+}
diff --git a/quartz/src/nativeMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.native.kt b/quartz/src/nativeMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.native.kt
new file mode 100644
index 0000000000..771c359161
--- /dev/null
+++ b/quartz/src/nativeMain/kotlin/com/vitorpamplona/quartz/utils/Secp256k1Instance.native.kt
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.utils
+
+import fr.acinq.secp256k1.Secp256k1
+
+actual object Secp256k1Instance {
+    private val h02 = Hex.decode("02")
+    private val secp256k1Ref = Secp256k1.get()
+
+    actual fun compressedPubKeyFor(privKey: ByteArray): ByteArray = secp256k1Ref.pubKeyCompress(secp256k1Ref.pubkeyCreate(privKey))
+
+    actual fun isPrivateKeyValid(il: ByteArray): Boolean = secp256k1Ref.secKeyVerify(il)
+
+    actual fun signSchnorr(
+        data: ByteArray,
+        privKey: ByteArray,
+        nonce: ByteArray?,
+    ): ByteArray = secp256k1Ref.signSchnorr(data, privKey, nonce)
+
+    actual fun signSchnorr(
+        data: ByteArray,
+        privKey: ByteArray,
+    ): ByteArray = secp256k1Ref.signSchnorr(data, privKey, null)
+
+    actual fun verifySchnorr(
+        signature: ByteArray,
+        hash: ByteArray,
+        pubKey: ByteArray,
+    ): Boolean = secp256k1Ref.verifySchnorr(signature, hash, pubKey)
+
+    actual fun privateKeyAdd(
+        first: ByteArray,
+        second: ByteArray,
+    ): ByteArray = secp256k1Ref.privKeyTweakAdd(first, second)
+
+    actual fun pubKeyTweakMulCompact(
+        pubKey: ByteArray,
+        privateKey: ByteArray,
+    ): ByteArray = secp256k1Ref.pubKeyTweakMul(h02 + pubKey, privateKey).copyOfRange(1, 33)
+}