spring-cloud-config: Encrypt/Decrypt Endpoints not working for Symmetric Key

I have setup a simple project using Spring Cloud Config Server and I’m trying to simply encrypt and decrypt some values. I create the project as a Spring Starter Project using the following pom.xml with Spring Boot.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.oreilly.cloud</groupId>
    <artifactId>spring-microservices-config-server6</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>spring-microservices-config-server6</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-config-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Camden.SR2</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

From there I modify the main Spring Boot Application class to add the @EnableConfigServer annotation as follows:

@SpringBootApplication
@EnableConfigServer
public class SpringMicroservicesConfigServer6Application {

    public static void main(String[] args) {
        SpringApplication.run(SpringMicroservicesConfigServer6Application.class, args);
    }
}

Within my application.properties file, I point to a git repository, setup the server port and enable symmetric key encryption using encrypt.key as follows:

server.port=8888
spring.cloud.config.server.git.uri=C:/Users/training/Desktop/sts-workspace/configuration
encrypt.key=secret

Next I open a bash shell and encrypt some data:

$ curl http://localhost:8888/encrypt -d Kevin

Which produces the value:

315ca5592635e4f65e0a0278cd08f74b5cef27e8379bd0e0d81d08c9ed8fbac161d

If I attempt to decrypt the value using:

curl localhost:8888/decrypt --data-urlencode 315ca5592635e4f65e0a0278cd08f74b5cef27e8379bd0e0d81d08c9ed8fbac161d

I receive the following error:

276{"description":"Text not encrypted with this key","status":"INVALID"}

I do not understand why this simple example does not work. I have confirmed my JCE extension is in place using some simple code to test the .jar files are in place. Is this an issue or am I missing something?