Both B4XEncryption and Encryption libraries can encrypt files.
If you can switch from PHP to B4J then you can use B4XEncryption as it is compatible with B4A, B4J and B4i.
Both B4XEncryption and Encryption libraries can encrypt files.
If you can switch from PHP to B4J then you can use B4XEncryption as it is compatible with B4A, B4J and B4i.