Which One Time Pad Cipher Would Be "Most Unbreakable" ?

[Point Conception]

Which of the two One Time Pad formats would be most secure ? This one ; https://en.wikipedia.org/wiki/One-time_pad With modular addition or following double key format . Message --> Key -->Key --> Cipher Text
For the same message HELLO. ( Each letter in alphabet is randomly keyed to A --> Z Then again randomly keyed to cipher text. ( repeating message letters are given numbers in first key)
HELLO ------------ message
KWB9J-------------key₁
PXNVG------------ key₂/cipher text

 

[jedishrfu]

Since you're using a one-time pad, then it seems that they would be equivalent. One-time pads can't be broken by cryptographic methods since the base values are generated randomly.

However, should someone steal a copy of the one-time pad then the extra encryption would marginally protect the message but over time it would be susceptible to cryptographics methods.

 

[nsaspook]

For pure cryptographic strength they would be equivalent but for communications channel security an extra level of stream cipher encryption generated from another random key is usually added (superencipherment) to prevent message traffic analysis so there is a random data stream at all times when no OTP cipher text is sent.