cannot locate symbol "EVP_cast5_cbc" on Android

Question

I recently built libssh2 for Android using OpenSSL as a crypto backend, I also built libcrypto.so and libssl.so myself using the NDK. In my build process I generate a final libcustom.so linked with libssh2.a.

Google said "If you tried to use your own copy of OpenSSL but forgot to bundle it with your app's APK, the app may run normally on versions of Android platform that includes libcrypto.so. However, the app could crash on later versions of Android that do not include this library (such as, Android 6.0 and later)." that's why I package libcrypto.so, libssl.so and libcustom.so into my APK.

When running an Android app that loads the libcustom.so, my app crashes with the following error: failed: dlopen failed: cannot locate symbol "EVP_cast5_cbc" referenced by "libcustom.so"... ONLY ON ANDROID 5. It works well on Android 6 and above.

The symbol EVP_cast5_cbc is undefined but referenced in libssh2.a, but well defined in libcrypto.so.

I don't understand why it runs correctly on Android 6 and above and not on Android 5.

I thought that on Android 5, the libcrypto.so used was not the one I embed in the APK but the one from /system/lib ; so I tried to rename the libcrypto.so and build libssh2.a using the libcrypto renamed, but I am facing the same issue.

Does anybody have an idea ?

Thank's in advance.

GensaGames GensaGames · Accepted Answer · 2019-11-06T17:42:29

Google has changed the use of private libraries for Marshmallow and above; this may be the case that you are experiencing.

Starting in Android 6.0, the system prevents apps from dynamically linking against non-NDK libraries, which may cause your app to crash.

According to this table: https://developer.android.com/about/versions/nougat/android-7.0-changes.html#ndk. You should be able to see logcat warnings when you are running Lollipop with private libraries. For example:

03-21 17:07:51.502 31234 31234 W linker  : library "libandroid_runtime.so"
("/system/lib/libandroid_runtime.so") needed or dlopened by
"/data/app/com.popular-app.android-2/lib/arm/libapplib.so" is not accessible
for the namespace "classloader-namespace" - the access is temporarily granted
as a workaround for http://b/26394120

cannot locate symbol "EVP_cast5_cbc" on Android

1 Answers