Gradle obfuscate string

build.gradle

apply from: "$rootDir/utils.gradle"

android {
    defaultConfig {
        buildConfigField 'String', 'SECRET_KEY', toJavaCodeString(SECRET_KEY)
    }
}

gradle.properties

SECRET_KEY=ab76239ef64454356754239ef6210898

utils.gradle

class Utils {
    static def r = new Random(System.currentTimeMillis())
}

def String toJavaCodeString(String string) {
    byte[] b = string.getBytes();
    int c = b.length;
    StringBuilder sb = new StringBuilder();

    sb.append("(new Object() {");
    sb.append("int t;");
    sb.append("public String toString() {");
    sb.append("byte[] buf = new byte[");
    sb.append(c);
    sb.append("];");

    for (int i = 0; i < c; ++i) {
        int t = Utils.r.nextInt();
        int f = Utils.r.nextInt(24) + 1;

        t = (t & ~(0xff << f)) | (b[i] << f);

        sb.append("t = ");
        sb.append(t);
        sb.append(";");
        sb.append("buf[");
        sb.append(i);
        sb.append("] = (byte) (t >>> ");
        sb.append(f);
        sb.append(");");
    }

    sb.append("return new String(buf);");
    sb.append("}}.toString())");

    return sb.toString();
}

ext.toJavaCodeString = this.&toJavaCodeString