diff --git a/index.js b/index.js
index 797e52e..b3e98f0 100644
--- a/index.js
+++ b/index.js
@@ -330,10 +330,10 @@ class Pass {
 								return bundleCallback(null);
 							});
 						}
-					], function _composeStream() {
+					], () => {
 						archive.append(JSON.stringify(manifest), { name: "manifest.json" });
 
-						let signatureBuffer = createSignature(manifest);
+						let signatureBuffer = this._sign(manifest);
 						archive.append(signatureBuffer, { name: "signature" });
 
 						let passStream = new stream.PassThrough();
@@ -349,6 +349,67 @@ class Pass {
 			});
 		});
 	}
+
+	/**
+		Generates the PKCS #7 cryptografic signature for the manifest file.
+
+		@method _sign
+		@params {String|Object} manifest - Manifest content.
+		@returns {Object} Promise
+	*/
+
+	_sign(manifest) {
+		let signature = forge.pkcs7.createSignedData();
+
+		if (typeof manifest === "object") {
+			signature.content = forge.util.createBuffer(JSON.stringify(manifest), "utf8")
+		} else if (typeof manifest === "string") {
+			signature.content = manifest;
+		} else {
+			throw new Error(`Manifest content must be a string or an object. Unable to accept manifest of type ${typeof manifest}`);
+		}
+
+		signature.addCertificate(Certificates.wwdr);
+		signature.addCertificate(Certificates.signerCert);
+
+		signature.addSigner({
+			key: Certificates.signerKey,
+			certificate: Certificates.signerCert,
+			digestAlgorithm: forge.pki.oids.sha1,
+			authenticatedAttributes: [{
+				type: forge.pki.oids.contentType,
+				value: forge.pki.oids.data
+			}, {
+				type: forge.pki.oids.messageDigest,
+			}, {
+				// the value is autogenerated
+				type: forge.pki.oids.signingTime,
+			}]
+		});
+
+		signature.sign();
+
+		/*
+		 * Signing creates in contentInfo a JSON object nested BER/TLV (X.690 standard) structure.
+		 * Each object represents a component of ASN.1 (Abstract Syntax Notation)
+		 * For a more complete reference, refer to: https://en.wikipedia.org/wiki/X.690#BER_encoding
+		 *
+		 * signature.contentInfo.type => SEQUENCE OF (16)
+		 * signature.contentInfo.value[0].type => OBJECT IDENTIFIER (6)
+		 * signature.contantInfo.value[1].type => END OF CONTENT (EOC - 0)
+		 *
+		 * EOC are only present only in constructed indefinite-length methods
+		 * Since `signature.contentInfo.value[1].value` contains an object whose value contains the content we passed,
+		 * we have to pop the whole object away to avoid signature content invalidation.
+		 *
+		 */
+		signature.contentInfo.value.pop();
+
+		// Converting the JSON Structure into a DER (which is a subset of BER), ASN.1 valid structure
+		// Returning the buffer of the signature
+
+		return Buffer.from(forge.asn1.toDer(signature.toAsn1()).getBytes(), 'binary');
+	}
 }
 
 
@@ -404,68 +465,6 @@ function loadConfiguration(setup) {
 	});
 }
 
-/**
-	Generates the PKCS #7 cryptografic signature for the manifest file.
-
-	@function createSignature
-	@params {String} manifestPath - temp dir path created to keep the manifest file.
-	@returns {Object} Promise
-*/
-
-
-function createSignature(manifest) {
-	let signature = forge.pkcs7.createSignedData();
-
-	if (typeof manifest === "object") {
-		signature.content = forge.util.createBuffer(JSON.stringify(manifest), "utf8")
-	} else if (typeof manifest === "string") {
-		signature.content = manifest;
-	} else {
-		throw new Error(`Manifest content must be a string or an object. Unable to accept manifest of type ${typeof manifest}`);
-	}
-
-	signature.addCertificate(Certificates.wwdr);
-	signature.addCertificate(Certificates.signerCert);
-
-	signature.addSigner({
-		key: Certificates.signerKey,
-		certificate: Certificates.signerCert,
-		digestAlgorithm: forge.pki.oids.sha1,
-		authenticatedAttributes: [{
-			type: forge.pki.oids.contentType,
-			value: forge.pki.oids.data
-		}, {
-			type: forge.pki.oids.messageDigest,
-		}, {
-			// the value is autogenerated
-			type: forge.pki.oids.signingTime,
-		}]
-	});
-
-	signature.sign();
-
-	/*
-	 * Signing creates in contentInfo a JSON object nested BER/TLV (X.690 standard) structure.
-	 * Each object represents a component of ASN.1 (Abstract Syntax Notation)
-	 * For a more complete reference, refer to: https://en.wikipedia.org/wiki/X.690#BER_encoding
-	 *
-	 * signature.contentInfo.type => SEQUENCE OF (16)
-	 * signature.contentInfo.value[0].type => OBJECT IDENTIFIER (6)
-	 * signature.contantInfo.value[1].type => END OF CONTENT (EOC - 0)
-	 *
-	 * EOC are only present only in constructed indefinite-length methods
-	 * Since `signature.contentInfo.value[1].value` contains an object whose value contains the content we passed,
-	 * we have to pop the whole object away to avoid signature content invalidation.
-	 *
-	 */
-	signature.contentInfo.value.pop();
-
-	// Converting the JSON Structure into a DER (which is a subset of BER), ASN.1 valid structure
-	// Returning the buffer of the signature
-
-	return Buffer.from(forge.asn1.toDer(signature.toAsn1()).getBytes(), 'binary');
-}
-
 /**
 	Filters the options received in the query from http request into supported options
 	by Apple and this application, based on the functions that can be provided to keys