diff --git a/buildSrc/src/main/groovy/verified-download.groovy b/buildSrc/src/main/groovy/verified-download.groovy
new file mode 100644
index 000000000..4ef4e338b
--- /dev/null
+++ b/buildSrc/src/main/groovy/verified-download.groovy
@@ -0,0 +1,46 @@
+import org.gradle.api.tasks.*
+
+
+////////////////////////////////////////////////////////////////////////
+//
+//  download and use checksum to verify that we got what we expected
+//
+
+class VerifiedDownload extends org.gradle.api.DefaultTask {
+
+	// URL of resource to download
+	def @Input src
+
+	// expected checksum of resource as hex digits
+	def @Input checksum
+
+	// algorithm to use for computing checksum
+	def @Input algorithm = 'MD5'
+
+	// whether to use ETag for selective downloading
+	def @Input useETag = true
+
+	// local file into which resource should be saved
+	def @OutputFile dest
+
+	File getDest() {
+		return project.file(dest)
+	}
+
+	@TaskAction
+	downloadAndVerify() {
+		def destFile = getDest()
+		project.download {
+			src this.src
+			dest destFile
+			overwrite true
+			onlyIfModified true
+			useETag this.useETag
+		}
+		project.verifyChecksum {
+			src destFile
+			algorithm this.algorithm
+			checksum this.checksum
+		}
+	}
+}
diff --git a/com.ibm.wala.cast.java.test.data/build.gradle b/com.ibm.wala.cast.java.test.data/build.gradle
index 4686420e6..8c6264a3e 100644
--- a/com.ibm.wala.cast.java.test.data/build.gradle
+++ b/com.ibm.wala.cast.java.test.data/build.gradle
@@ -6,31 +6,10 @@ sourceSets.test.java.srcDirs = ['src']
 //  download JLex
 //
 
-class VerifiedDownload extends org.gradle.api.DefaultTask {
-
-	@Input String src
-	@Input String checksum
-	@OutputFile File dest
-
-	@TaskAction
-	downloadAndVerify() {
-		download {
-			src this.src
-			dest this.dest
-			overwrite true
-			onlyIfModified true
-		}
-		verifyChecksum {
-			src this.dest
-			checksum this.checksum
-		}
-	}
-}
-
 task downloadJLex(type: VerifiedDownload) {
 	src 'http://www.cs.princeton.edu/~appel/modern/java/JLex/current/Main.java'
 	checksum 'fe0cff5db3e2f0f5d67a153cf6c783af'
-	dest file('src/JLex/Main.java')
+	dest 'src/JLex/Main.java'
 }
 
 task cleanDownloadJLex(type: Delete) {
diff --git a/com.ibm.wala.cast.js.nodejs/build.gradle b/com.ibm.wala.cast.js.nodejs/build.gradle
index 24a603a04..c8c9afd87 100644
--- a/com.ibm.wala.cast.js.nodejs/build.gradle
+++ b/com.ibm.wala.cast.js.nodejs/build.gradle
@@ -10,21 +10,10 @@ dependencies {
 		)
 }
 
-task downloadNodeJS {
-	outputs.file "$temporaryDir/nodejs.zip"
-	doLast {
-		download {
-			src 'https://api.github.com/repos/nodejs/node/zipball/0a604e92e258c5ee2752d763e50721e35053f135'
-			dest outputs.files.singleFile
-			overwrite true
-			onlyIfModified true
-			useETag true
-		}
-		verifyChecksum {
-			src outputs.files.singleFile
-			checksum '33c5ba7a5d45644e70d268d8ad3e57df'
-		}
-	}
+task downloadNodeJS(type: VerifiedDownload) {
+	src 'https://api.github.com/repos/nodejs/node/zipball/0a604e92e258c5ee2752d763e50721e35053f135'
+	dest "$temporaryDir/nodejs.zip"
+	checksum '33c5ba7a5d45644e70d268d8ad3e57df'
 }
 
 task unpackNodeJSLib(type: Copy, dependsOn: downloadNodeJS) {
diff --git a/com.ibm.wala.cast.js.test.data/build.gradle b/com.ibm.wala.cast.js.test.data/build.gradle
index acb178841..0bd43a3f3 100644
--- a/com.ibm.wala.cast.js.test.data/build.gradle
+++ b/com.ibm.wala.cast.js.test.data/build.gradle
@@ -1,22 +1,11 @@
 apply plugin: 'base'
 
-task downloadAjaxslt {
+task downloadAjaxslt(type: VerifiedDownload) {
 	def version = '0.8.1'
 	def versionedArchive = "ajaxslt-${version}.tar.gz"
-	outputs.file "$temporaryDir/$versionedArchive"
-	doLast {
-		download {
-			src "https://storage.googleapis.com/google-code-archive-downloads/v2/code.google.com/ajaxslt/$versionedArchive"
-			dest outputs.files.singleFile
-			overwrite true
-			onlyIfModified true
-			useETag true
-		}
-		verifyChecksum {
-			src outputs.files.singleFile
-			checksum 'c995abe3310a401bb4db7f28a6409756'
-		}
-	}
+	src "https://storage.googleapis.com/google-code-archive-downloads/v2/code.google.com/ajaxslt/$versionedArchive"
+	dest "$temporaryDir/$versionedArchive"
+	checksum 'c995abe3310a401bb4db7f28a6409756'
 }
 
 task unpackAjaxslt(type: Sync, dependsOn: downloadAjaxslt) {
diff --git a/com.ibm.wala.core.testdata/build.gradle b/com.ibm.wala.core.testdata/build.gradle
index d8d34ee3d..b77b5e8a9 100644
--- a/com.ibm.wala.core.testdata/build.gradle
+++ b/com.ibm.wala.core.testdata/build.gradle
@@ -10,25 +10,13 @@ sourceSets.test.java.srcDirs = ['src']
 //  download and extract "bcel-5.2.jar"
 //
 
-task downloadBcel {
-	ext {
-		version = '5.2'
-	}
+task downloadBcel(type: VerifiedDownload) {
+	ext.version = '5.2'
 	def archive = "bcel-${version}.tar.gz"
-	outputs.file "$temporaryDir/$archive"
-	doLast {
-		download {
-			src "http://archive.apache.org/dist/jakarta/bcel/binaries/$archive"
-			dest outputs.files.singleFile
-			overwrite true
-			onlyIfModified true
-			useETag false // server does not provide ETags
-		}
-		verifyChecksum {
-			src outputs.files.singleFile
-			checksum '19bffd7f217b0eae415f1ef87af2f0bc'
-		}
-	}
+	src "http://archive.apache.org/dist/jakarta/bcel/binaries/$archive"
+	dest "$temporaryDir/$archive"
+	checksum '19bffd7f217b0eae415f1ef87af2f0bc'
+	useETag false
 }
 
 task extractBcel(type: Copy, dependsOn: downloadBcel) {
@@ -56,22 +44,11 @@ clean.dependsOn cleanExtractBcel
 //  download "java-cup-11a.jar"
 //
 
-task downloadJavaCup {
+task downloadJavaCup(type: VerifiedDownload) {
 	def archive = 'java-cup-11a.jar'
-	outputs.file "$projectDir/$archive"
-	doLast {
-		download {
-			src "http://www2.cs.tum.edu/projects/cup/$archive"
-			dest outputs.files.singleFile
-			overwrite true
-			onlyIfModified true
-			useETag true
-		}
-		verifyChecksum {
-			src outputs.files.singleFile
-			checksum '2bda8c40abd0cbc295d3038643d6e4ec'
-		}
-	}
+	src "http://www2.cs.tum.edu/projects/cup/$archive"
+	dest "$projectDir/$archive"
+	checksum '2bda8c40abd0cbc295d3038643d6e4ec'
 }
 
 task cleanDownloadJavaCup(type: Delete) {
@@ -106,24 +83,13 @@ clean.dependsOn cleanCollectJLex
 //  generate "hello_hash.jar"
 //
 
-task downloadOcamlJava {
+task downloadOcamlJava(type: VerifiedDownload) {
 	def version = '2.0-alpha1'
 	ext.basename = "ocamljava-$version"
 	def archive = "${basename}.tar.gz"
-	outputs.file "$temporaryDir/$archive"
-	doLast {
-		download {
-			src "http://www.ocamljava.org/downloads/download.php?version=$version-bin"
-			dest outputs.files.singleFile
-			overwrite true
-			onlyIfModified true
-			useETag true
-		}
-		verifyChecksum {
-			src outputs.files.singleFile
-			checksum '45feec6e3889f5073a39c2c4c84878d1'
-		}
-	}
+	src "http://www.ocamljava.org/downloads/download.php?version=$version-bin"
+	dest "$temporaryDir/$archive"
+	checksum '45feec6e3889f5073a39c2c4c84878d1'
 }
 
 task unpackOcamlJava(type: Sync, dependsOn: downloadOcamlJava) {
diff --git a/com.ibm.wala.dalvik.test/build.gradle b/com.ibm.wala.dalvik.test/build.gradle
index 682e3f7ef..e3b336267 100644
--- a/com.ibm.wala.dalvik.test/build.gradle
+++ b/com.ibm.wala.dalvik.test/build.gradle
@@ -16,39 +16,26 @@ task cloneDroidBench(type: Exec) {
 	commandLine 'git', 'clone', "--branch=$inputs.properties.branch", '--config=advice.detachedHead=false', '--depth=1', '--quiet', inputs.properties.repository, destDir
 }
 
-task downloadAndroidSdk {
+task downloadAndroidSdk(type: VerifiedDownload) {
 	def sdkOs
-	def sdkChecksum
 	switch (System.getProperty('os.name')) {
 		case ~/Linux/:
 			sdkOs = 'linux'
-			sdkChecksum = '444e22ce8ca0f67353bda4b85175ed3731cae3ffa695ca18119cbacef1c1bea0'
+			checksum '444e22ce8ca0f67353bda4b85175ed3731cae3ffa695ca18119cbacef1c1bea0'
 			break
 		case ~/Mac OS X/:
 			sdkOs = 'darwin'
-			sdkChecksum = '4a81754a760fce88cba74d69c364b05b31c53d57b26f9f82355c61d5fe4b9df9'
+			checksum '4a81754a760fce88cba74d69c364b05b31c53d57b26f9f82355c61d5fe4b9df9'
 			break
 		case ~/Windows.*/:
 			sdkOs = 'windows'
-			sdkChecksum = '7f6037d3a7d6789b4fdc06ee7af041e071e9860c51f66f7a4eb5913df9871fd2'
+			checksum '7f6037d3a7d6789b4fdc06ee7af041e071e9860c51f66f7a4eb5913df9871fd2'
 			break
 	}
 	def archive = "sdk-tools-$sdkOs-3859397.zip"
-	outputs.file "$temporaryDir/$archive"
-	doLast {
-		download {
-			src "https://dl.google.com/android/repository/$archive"
-			dest outputs.files.singleFile
-			overwrite true
-			onlyIfModified true
-			useETag true
-		}
-		verifyChecksum {
-			src outputs.files.singleFile
-			algorithm 'SHA-256'
-			checksum sdkChecksum
-		}
-	}
+	src "https://dl.google.com/android/repository/$archive"
+	dest "$temporaryDir/$archive"
+	algorithm 'SHA-256'
 }
 
 task unpackAndroidSdk(type: Sync, dependsOn: downloadAndroidSdk) {
@@ -86,38 +73,16 @@ task copyAndroidJar(type: Sync, dependsOn: installAndroidPlatforms) {
 	into temporaryDir
 }
 
-task downloadSampleCup {
-	outputs.file 'data/sample.cup'
-	doLast {
-		download {
-			src 'http://www.cc.gatech.edu/gvu/people/faculty/hudson/java_cup/classes.v0.9e/java_cup/parser.cup'
-			dest outputs.files.singleFile
-			overwrite true
-			onlyIfModified true
-			useETag true
-		}
-		verifyChecksum {
-			src outputs.files.singleFile
-			checksum '76b549e7c6e802b811a374248175ecf4'
-		}
-	}
+task downloadSampleCup(type: VerifiedDownload) {
+	src 'http://www.cc.gatech.edu/gvu/people/faculty/hudson/java_cup/classes.v0.9e/java_cup/parser.cup'
+	dest 'data/sample.cup'
+	checksum '76b549e7c6e802b811a374248175ecf4'
 }
 
-task downloadSampleLex {
-	outputs.file 'data/sample.lex'
-	doLast {
-		download {
-			src 'https://www.cs.princeton.edu/~appel/modern/java/JLex/current/sample.lex'
-			dest outputs.files.singleFile
-			overwrite true
-			onlyIfModified true
-			useETag true
-		}
-		verifyChecksum {
-			src outputs.files.singleFile
-			checksum 'ae887758b2657981d023a72a165da830'
-		}
-	}
+task downloadSampleLex(type: VerifiedDownload) {
+	src 'https://www.cs.princeton.edu/~appel/modern/java/JLex/current/sample.lex'
+	dest 'data/sample.lex'
+	checksum 'ae887758b2657981d023a72a165da830'
 }
 
 clean.dependsOn cleanCopyDxJar