add secp256k1 library for schnorr

Author: alfonsobries

build.gradle

@@ -15,12 +15,17 @@ targetCompatibility = 1.8
 repositories {
     mavenLocal()
     mavenCentral()
+    flatDir {
+        dirs 'libs'
+    }
 }
 
 dependencies {
     implementation group: 'org.bitcoinj', name: 'bitcoinj-core', version: '0.15.8'
     implementation group: 'com.google.code.gson', name: 'gson', version: '2.8.6'
     implementation 'com.google.guava:guava:30.1.1-jre'
+    // Compiled from https://gitlab.com/bitcoinj/secp256k1-jdk
+    implementation name: 'secp256k1-api-0.0.1'
 
     testCompileOnly 'org.slf4j:slf4j-api:1.7.32'
     testRuntimeOnly 'org.slf4j:slf4j-simple:1.7.32'