Obfuscate android builds using proguard

The new android SDK comes with proguard included in the build system. You can check how to use it at http://developer.android.com/guide/developing/tools/proguard.html

Not all the proguard options can be used, specially those used for optimizations.

You should keep all classes used in xml files. The best way to do it is to keep classes that extend from android.content.Context due to almost everything related to android UI and services belong to the android context.

After some research I give you the best proguard.cfg for almost any application.


-dontpreverify
-dontskipnonpubliclibraryclasses
-dontskipnonpubliclibraryclassmembers
-optimizations !code/simplification/arithmetic
-optimizationpasses 5
-useuniqueclassmembernames
-dontusemixedcaseclassnames
-verbose
-target 1.6
# -repackageclasses mypackage

-keep public class * extends android.content.Context {
  *** (...);
}

-keepclassmembers enum * {
    public static **[] values();
    public static ** valueOf(java.lang.String);
}

-keepattributes Exceptions, InnerClasses, Signature

# Keep names - Native method names. Keep all native class/method names.
-keepclasseswithmembers,allowshrinking class * {
    native ;
}

-assumenosideeffects public class android.util.Log {
  *** *(...);
}

# Remove - System method calls. Remove all invocations of System
# methods without side effects whose return values are not used.
-assumenosideeffects public class java.lang.System {
    public static long currentTimeMillis();
    static java.lang.Class getCallerClass();
    public static int identityHashCode(java.lang.Object);
    public static java.lang.SecurityManager getSecurityManager();
    public static java.util.Properties getProperties();
    public static java.lang.String getProperty(java.lang.String);
    public static java.lang.String getenv(java.lang.String);
    public static java.lang.String mapLibraryName(java.lang.String);
    public static java.lang.String getProperty(java.lang.String,java.lang.String);
}

# Remove - Math method calls. Remove all invocations of Math
# methods without side effects whose return values are not used.
-assumenosideeffects public class java.lang.Math {
    public static double sin(double);
    public static double cos(double);
    public static double tan(double);
    public static double asin(double);
    public static double acos(double);
    public static double atan(double);
    public static double toRadians(double);
    public static double toDegrees(double);
    public static double exp(double);
    public static double log(double);
    public static double log10(double);
    public static double sqrt(double);
    public static double cbrt(double);
    public static double IEEEremainder(double,double);
    public static double ceil(double);
    public static double floor(double);
    public static double rint(double);
    public static double atan2(double,double);
    public static double pow(double,double);
    public static int round(float);
    public static long round(double);
    public static double random();
    public static int abs(int);
    public static long abs(long);
    public static float abs(float);
    public static double abs(double);
    public static int max(int,int);
    public static long max(long,long);
    public static float max(float,float);
    public static double max(double,double);
    public static int min(int,int);
    public static long min(long,long);
    public static float min(float,float);
    public static double min(double,double);
    public static double ulp(double);
    public static float ulp(float);
    public static double signum(double);
    public static float signum(float);
    public static double sinh(double);
    public static double cosh(double);
    public static double tanh(double);
    public static double hypot(double,double);
    public static double expm1(double);
    public static double log1p(double);
}

# Remove - Number method calls. Remove all invocations of Number
# methods without side effects whose return values are not used.
-assumenosideeffects public class java.lang.* extends java.lang.Number {
    public static java.lang.String toString(byte);
    public static java.lang.Byte valueOf(byte);
    public static byte parseByte(java.lang.String);
    public static byte parseByte(java.lang.String,int);
    public static java.lang.Byte valueOf(java.lang.String,int);
    public static java.lang.Byte valueOf(java.lang.String);
    public static java.lang.Byte decode(java.lang.String);
    public int compareTo(java.lang.Byte);
    public static java.lang.String toString(short);
    public static short parseShort(java.lang.String);
    public static short parseShort(java.lang.String,int);
    public static java.lang.Short valueOf(java.lang.String,int);
    public static java.lang.Short valueOf(java.lang.String);
    public static java.lang.Short valueOf(short);
    public static java.lang.Short decode(java.lang.String);
    public static short reverseBytes(short);
    public int compareTo(java.lang.Short);
    public static java.lang.String toString(int,int);
    public static java.lang.String toHexString(int);
    public static java.lang.String toOctalString(int);
    public static java.lang.String toBinaryString(int);
    public static java.lang.String toString(int);
    public static int parseInt(java.lang.String,int);
    public static int parseInt(java.lang.String);
    public static java.lang.Integer valueOf(java.lang.String,int);
    public static java.lang.Integer valueOf(java.lang.String);
    public static java.lang.Integer valueOf(int);
    public static java.lang.Integer getInteger(java.lang.String);
    public static java.lang.Integer getInteger(java.lang.String,int);
    public static java.lang.Integer getInteger(java.lang.String,java.lang.Integer);
    public static java.lang.Integer decode(java.lang.String);
    public static int highestOneBit(int);
    public static int lowestOneBit(int);
    public static int numberOfLeadingZeros(int);
    public static int numberOfTrailingZeros(int);
    public static int bitCount(int);
    public static int rotateLeft(int,int);
    public static int rotateRight(int,int);
    public static int reverse(int);
    public static int signum(int);
    public static int reverseBytes(int);
    public int compareTo(java.lang.Integer);
    public static java.lang.String toString(long,int);
    public static java.lang.String toHexString(long);
    public static java.lang.String toOctalString(long);
    public static java.lang.String toBinaryString(long);
    public static java.lang.String toString(long);
    public static long parseLong(java.lang.String,int);
    public static long parseLong(java.lang.String);
    public static java.lang.Long valueOf(java.lang.String,int);
    public static java.lang.Long valueOf(java.lang.String);
    public static java.lang.Long valueOf(long);
    public static java.lang.Long decode(java.lang.String);
    public static java.lang.Long getLong(java.lang.String);
    public static java.lang.Long getLong(java.lang.String,long);
    public static java.lang.Long getLong(java.lang.String,java.lang.Long);
    public static long highestOneBit(long);
    public static long lowestOneBit(long);
    public static int numberOfLeadingZeros(long);
    public static int numberOfTrailingZeros(long);
    public static int bitCount(long);
    public static long rotateLeft(long,int);
    public static long rotateRight(long,int);
    public static long reverse(long);
    public static int signum(long);
    public static long reverseBytes(long);
    public int compareTo(java.lang.Long);
    public static java.lang.String toString(float);
    public static java.lang.String toHexString(float);
    public static java.lang.Float valueOf(java.lang.String);
    public static java.lang.Float valueOf(float);
    public static float parseFloat(java.lang.String);
    public static boolean isNaN(float);
    public static boolean isInfinite(float);
    public static int floatToIntBits(float);
    public static int floatToRawIntBits(float);
    public static float intBitsToFloat(int);
    public static int compare(float,float);
    public boolean isNaN();
    public boolean isInfinite();
    public int compareTo(java.lang.Float);
    public static java.lang.String toString(double);
    public static java.lang.String toHexString(double);
    public static java.lang.Double valueOf(java.lang.String);
    public static java.lang.Double valueOf(double);
    public static double parseDouble(java.lang.String);
    public static boolean isNaN(double);
    public static boolean isInfinite(double);
    public static long doubleToLongBits(double);
    public static long doubleToRawLongBits(double);
    public static double longBitsToDouble(long);
    public static int compare(double,double);
    public boolean isNaN();
    public boolean isInfinite();
    public int compareTo(java.lang.Double);
    public (byte);
    public (short);
    public (int);
    public (long);
    public (float);
    public (double);
    public (java.lang.String);
    public byte byteValue();
    public short shortValue();
    public int intValue();
    public long longValue();
    public float floatValue();
    public double doubleValue();
    public int compareTo(java.lang.Object);
    public boolean equals(java.lang.Object);
    public int hashCode();
    public java.lang.String toString();
}

# Remove - String method calls. Remove all invocations of String
# methods without side effects whose return values are not used.
-assumenosideeffects public class java.lang.String {
    public ();
    public (byte[]);
    public (byte[],int);
    public (byte[],int,int);
    public (byte[],int,int,int);
    public (byte[],int,int,java.lang.String);
    public (byte[],java.lang.String);
    public (char[]);
    public (char[],int,int);
    public (java.lang.String);
    public (java.lang.StringBuffer);
    public static java.lang.String copyValueOf(char[]);
    public static java.lang.String copyValueOf(char[],int,int);
    public static java.lang.String valueOf(boolean);
    public static java.lang.String valueOf(char);
    public static java.lang.String valueOf(char[]);
    public static java.lang.String valueOf(char[],int,int);
    public static java.lang.String valueOf(double);
    public static java.lang.String valueOf(float);
    public static java.lang.String valueOf(int);
    public static java.lang.String valueOf(java.lang.Object);
    public static java.lang.String valueOf(long);
    public boolean contentEquals(java.lang.StringBuffer);
    public boolean endsWith(java.lang.String);
    public boolean equalsIgnoreCase(java.lang.String);
    public boolean equals(java.lang.Object);
    public boolean matches(java.lang.String);
    public boolean regionMatches(boolean,int,java.lang.String,int,int);
    public boolean regionMatches(int,java.lang.String,int,int);
    public boolean startsWith(java.lang.String);
    public boolean startsWith(java.lang.String,int);
    public byte[] getBytes();
    public byte[] getBytes(java.lang.String);
    public char charAt(int);
    public char[] toCharArray();
    public int compareToIgnoreCase(java.lang.String);
    public int compareTo(java.lang.Object);
    public int compareTo(java.lang.String);
    public int hashCode();
    public int indexOf(int);
    public int indexOf(int,int);
    public int indexOf(java.lang.String);
    public int indexOf(java.lang.String,int);
    public int lastIndexOf(int);
    public int lastIndexOf(int,int);
    public int lastIndexOf(java.lang.String);
    public int lastIndexOf(java.lang.String,int);
    public int length();
    public java.lang.CharSequence subSequence(int,int);
    public java.lang.String concat(java.lang.String);
    public java.lang.String replaceAll(java.lang.String,java.lang.String);
    public java.lang.String replace(char,char);
    public java.lang.String replaceFirst(java.lang.String,java.lang.String);
    public java.lang.String[] split(java.lang.String);
    public java.lang.String[] split(java.lang.String,int);
    public java.lang.String substring(int);
    public java.lang.String substring(int,int);
    public java.lang.String toLowerCase();
    public java.lang.String toLowerCase(java.util.Locale);
    public java.lang.String toString();
    public java.lang.String toUpperCase();
    public java.lang.String toUpperCase(java.util.Locale);
    public java.lang.String trim();
}

# Remove - StringBuffer method calls. Remove all invocations of StringBuffer
# methods without side effects whose return values are not used.
-assumenosideeffects public class java.lang.StringBuffer {
    public ();
    public (int);
    public (java.lang.String);
    public (java.lang.CharSequence);
    public java.lang.String toString();
    public char charAt(int);
    public int capacity();
    public int codePointAt(int);
    public int codePointBefore(int);
    public int indexOf(java.lang.String,int);
    public int lastIndexOf(java.lang.String);
    public int lastIndexOf(java.lang.String,int);
    public int length();
    public java.lang.String substring(int);
    public java.lang.String substring(int,int);
}

# Remove - StringBuilder method calls. Remove all invocations of StringBuilder
# methods without side effects whose return values are not used.
-assumenosideeffects public class java.lang.StringBuilder {
    public ();
    public (int);
    public (java.lang.String);
    public (java.lang.CharSequence);
    public java.lang.String toString();
    public char charAt(int);
    public int capacity();
    public int codePointAt(int);
    public int codePointBefore(int);
    public int indexOf(java.lang.String,int);
    public int lastIndexOf(java.lang.String);
    public int lastIndexOf(java.lang.String,int);
    public int length();
    public java.lang.String substring(int);
    public java.lang.String substring(int,int);
}

BR,

Lula