Combining a block cipher with a (pseudo) OTP
There's quite a few things wrong with this. For starters, a block cipher does not imply authentication. Common block cipher modes such as CTR, CBC, and (god forbid) ECB provide nothing but pure encryption. If you want authentication, look into the GCM block cipher. AES-GCM is possibly the better way to go here.

You state that it is built on the idea that every bit is important when deciphering the data, but this is simply not true. It is difficult (to my knowledge) to have a block cipher rely on every bit of the ciphertext for decryption to be successful. The best thing you can get is having a block cipher rely on every previous bit, meaning you can decrypt the first half of the data just fine while ignoring the second half.

If you have a working OTP, why are you bothering with a block cipher? Just digitally sign it or use a MAC and it will be authenticated. Other than that, an OTP provides perfect secrecy. (Don't be fooled, this is for a perfect OTP, which is virtually impossible to do correctly)

If you are dead set on your OTP &amp; block cipher combo, then I suggest using AES in GCM mode as your block cipher, followed by a newly generated OTP (or a removed section of an existing OTP generated for use in encryption).

However, AES-GCM alone will do what you are looking for without the need of a OTP. And considering how difficult it is to pull off using a real OTP, it's probably more secure just sticking with AES.