feat: add webhook validation

src/main/kotlin/Validate.kt

@@ -0,0 +1,63 @@
+@file:JvmName("OpenSSL")
+
+package br.com.openpix.sdk
+
+import io.ktor.util.*
+import java.security.KeyFactory
+import java.security.PublicKey
+import java.security.Signature
+import java.security.spec.X509EncodedKeySpec
+
+/**
+ * The public key used to verify the signature of the webhook.
+ *
+ * @see verify
+ */
+@Suppress("MaxLineLength", "ktlint")
+public const val PUBLIC_KEY: String =
+  "LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUlHZk1BMEdDU3FHU0liM0RRRUJBUVVBQTRHTkFEQ0JpUUtCZ1FDLytOdElranpldnZxRCtJM01NdjNiTFhEdApwdnhCalk0QnNSclNkY2EzcnRBd01jUllZdnhTbmQ3amFnVkxwY3RNaU94UU84aWVVQ0tMU1dIcHNNQWpPL3paCldNS2Jxb0c4TU5waS91M2ZwNnp6MG1jSENPU3FZc1BVVUcxOWJ1VzhiaXM1WloySVpnQk9iV1NwVHZKMGNuajYKSEtCQUE4MkpsbitsR3dTMU13SURBUUFCCi0tLS0tRU5EIFBVQkxJQyBLRVktLS0tLQo=" // ktlint-disable
+
+/**
+ * The certificate used to verify the signature of the webhook.
+ *
+ * @see verify
+ */
+private val publicKey: PublicKey = run {
+  val base64 = PUBLIC_KEY.decodeBase64String()
+    .replace("-----BEGIN PUBLIC KEY-----", "")
+    .replace("\\n", "")
+    .replace("\n", "")
+    .replace("-----END PUBLIC KEY-----", "")
+    .decodeBase64Bytes()
+
+  KeyFactory
+    .getInstance("RSA")
+    .generatePublic(X509EncodedKeySpec(base64))
+}
+
+/**
+ * Verifies the signature of the webhook.
+ *
+ * ```java
+ * String payload;
+ * String signature;
+ *
+ * OpenSSL.verify(payload, signature);
+ * ```
+ *
+ * @param payload The payload of the webhook.
+ * @param signature The signature of the webhook.
+ * @return `true` if the signature is valid, `false` otherwise.
+ */
+public fun verify(payload: String, signature: String): Boolean {
+  runCatching {
+    return Signature.getInstance("SHA256withRSA").run {
+      initVerify(publicKey)
+      update(payload.toByteArray())
+
+      verify(signature.decodeBase64Bytes())
+    }
+  }.getOrElse {
+    return false
+  }
+}

src/test/kotlin/ValidateTests.kt

@@ -0,0 +1,31 @@
+package br.com.openpix.sdk
+
+import org.assertj.core.api.Assertions.*
+import org.junit.jupiter.api.Test
+
+class ValidateTests {
+  companion object {
+    @Suppress("MaxLineLength", "ktlint")
+    const val PAYLOAD: String =
+      """{ "pixQrCode": null, "charge": { "status": "COMPLETED", "customer": { "name": "Antonio Victor", "taxID": { "taxID": "12345678976", "type": "BR:CPF" }, "email": "antoniocliente@example.com", "correlationID": "4979ceba-2132-4292-bd90-bee7fb2125e4" }, "value": 1000, "comment": "Pagamento OpenPix", "transactionID": "ea83401ed4834b3ea6f1f283b389af29", "correlationID": "417bae21-3d08-4cdb-9c2d-fee63c89e9e4", "paymentLinkID": "34697ed2-3790-4b60-8512-e7465b142d84", "createdAt": "2021-03-12T12:43:54.528Z", "updatedAt": "2021-03-12T12:44:09.360Z", "brCode": "https://api.openpix.com.br/openpix/openpix/testing?transactionID=ea83401ed4834b3ea6f1f283b389af29" }, "pix": { "charge": { "status": "COMPLETED", "customer": { "name": "Antonio Victor", "taxID": { "taxID": "12345678976", "type": "BR:CPF" }, "email": "antoniocliente@example.com", "correlationID": "4979ceba-2132-4292-bd90-bee7fb2125e4" }, "value": 1000, "comment": "Pagamento OpenPix", "transactionID": "ea83401ed4834b3ea6f1f283b389af29", "correlationID": "417bae21-3d08-4cdb-9c2d-fee63c89e9e4", "paymentLinkID": "34697ed2-3790-4b60-8512-e7465b142d84", "createdAt": "2021-03-12T12:43:54.528Z", "updatedAt": "2021-03-12T12:44:09.360Z" }, "customer": { "correlationID": "9134e286-6f71-427a-bf00-241681624586", "email": "email1@example.com", "name": "Loma", "phone": "+5511999999999", "taxID": { "taxID": "47043622050", "type": "BR:CPF" } }, "payer": { "correlationID": "9134e286-6f71-427a-bf00-241681624586", "email": "email1@example.com", "name": "Loma", "phone": "+5511999999999", "taxID": { "taxID": "47043622050", "type": "BR:CPF" } }, "time": "2021-03-12T12:44:09.269Z", "value": 1, "transactionID": "ea83401ed4834b3ea6f1f283b389af29", "infoPagador": "OpenPix testing" }, "company": { "id": "624f46f9e93f9f521c8308d7", "name": "Pizzaria do José", "taxID": "4722767300014" }, "account": { "clientId": "ZOJ64B9B-ZM1W-89MI-4UCI-OP2LVIU6NY75" } }""" // ktlint-disable
+
+    @Suppress("MaxLineLength", "ktlint")
+    const val SIGNATURE: String =
+      "lL2nnXgmLFGgxJ8+jCDguqouU4ucrIxYJcU5SPrJFaNcJajTJHYVldqc/z4YFIjAjtPEALe699WosgPY08W7CLpidvtm06Qwa4YMB0l/DcTS93O91NdSH/adjugEKiOb76Zj/0jB8mqOmWCFYbweOBa17bssuEkd5Lw7Q5L314Y=" // ktlint-disable
+  }
+
+  @Test
+  fun `verify true`() {
+    assertThat(verify(PAYLOAD, SIGNATURE)).isTrue()
+  }
+
+  @Test
+  fun `verify false with payload`() {
+    assertThat(verify("{ \"payload\": \"invalid\" }", SIGNATURE)).isFalse()
+  }
+
+  @Test
+  fun `verify false with signature`() {
+    assertThat(verify(PAYLOAD, "no")).isFalse()
+  }
+}