first version credential provider

crypto/build.gradle

@@ -9,7 +9,7 @@ android {
     ndkVersion "21.4.7075529"
 
     defaultConfig {
-        minSdkVersion 15
+        minSdkVersion 19
         targetSdkVersion 34
         multiDexEnabled true
 
@@ -40,7 +40,7 @@ android {
 
 dependencies {
     // Crypto
-    implementation 'org.bouncycastle:bcprov-jdk15on:1.70'
+    implementation 'org.bouncycastle:bcpkix-jdk18on:1.78.1'
 
     testImplementation "androidx.test:runner:$android_test_version"
 }

crypto/src/main/java/com/kunzisoft/signature/Signature.kt

@@ -0,0 +1,43 @@
+package com.kunzisoft.signature
+
+import android.util.Log
+import org.bouncycastle.asn1.pkcs.PrivateKeyInfo
+import org.bouncycastle.jce.provider.BouncyCastleProvider
+import java.io.StringReader
+import java.security.PrivateKey
+import java.security.Security
+import java.security.Signature
+
+import org.bouncycastle.openssl.PEMParser
+import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter
+
+object Signature {
+
+    init {
+        Security.removeProvider(BouncyCastleProvider.PROVIDER_NAME)
+        Security.addProvider(BouncyCastleProvider())
+    }
+    fun sign(privateKeyPem: String, message: ByteArray): ByteArray {
+        val privateKey = createPrivateKey(privateKeyPem)
+        val algorithmKey = privateKey.algorithm
+        val algorithmSignature = when (algorithmKey) {
+            "EC" -> "SHA256withECDSA"
+            "ECDSA" -> "SHA256withECDSA"
+            "RSA" -> "SHA256withRSA"
+            else -> "no signature algorithms known"
+        }
+        val sig = Signature.getInstance(algorithmSignature, BouncyCastleProvider.PROVIDER_NAME)
+        sig.initSign(privateKey)
+        sig.update(message)
+        return sig.sign()
+    }
+
+    private fun createPrivateKey(privateKeyPem: String): PrivateKey {
+        val targetReader = StringReader(privateKeyPem);
+        val a = PEMParser(targetReader)
+        val privateKeyInfo = a.readObject() as PrivateKeyInfo
+        val privateKey = JcaPEMKeyConverter().getPrivateKey(privateKeyInfo)
+        return privateKey
+    }
+
+}