Hi, lovely app. Good job attaching apk files to your releases. However, this is neither OTP encryption nor secure in a cryptographic context. The One Time Pad creates a randomly generated pad on its own and uses the XOR function to combine the pad and plaintext together.

Instead, this app forces you to create the pad yourself, and only allows the pad to contain the ASCII characters 0-9. This means you cannot get the full 8 bit entropy for each byte. Because of this, if the character in the ciphertext is “q”, for example, you have only 10 options for the plaintext:

q xor 0 = A

q xor 1 = @

q xor 2 = C

q xor 3 = B

q xor 4 = E

q xor 5 = D

q xor 6 = G

q xor 7 = F

q xor 8 = I

q xor 9 = H