A, B, C, ......... Z represent the numbers from 1, 2, 3,...... 26. There is an encryption technique which uses a key. Key can be any number less than 26 and greater than 0. For a message ABCD, if key is 1, encrypted message becomes BCDE. Similarly, if the key is 5, and message is XYZA, the encrypted message becomes CDEF. If you get an encrypted message from a friend as 'FCJN'. This was encrypted using key = 24. The original message is ___ .
A, B, C, ......... Z represent the numbers from 1, 2, 3,...... 26. There is an encryption technique which uses a key. Key can be any number less than 26 and greater than 0. For a message ABCD, if key is 1, encrypted message becomes BCDE. Similarly, if the key is 5, and message is XYZA, the encrypted message becomes CDEF. If you get an encrypted message from a friend as 'FCJN'. This was encrypted using key = 24. The original message is
FCJN is encrypted message using key 24. Let αϒβθ be the original message. Suppose AB is encrypted to CD by using key 2. How do we decrypt it? We can't use the same key of course because using a key equal to 2 on CD will give EF. Actually if key used to encrypt message is φ, then the key used to decrypt message is (26 - φ). So, to decrypt the message FCJN, we have to use key (26 - 24) = 2.
FCJN with key = 2 becomes HELP
FCJN is encrypted message using key 24. Let αϒβθ be the original message. Suppose AB is encrypted to CD by using key 2. How do we decrypt it? We can't use the same key of course because using a key equal to 2 on CD will give EF. Actually if key used to encrypt message is φ, then the key used to decrypt message is (26 - φ). So, to decrypt the message FCJN, we have to use key (26 - 24) = 2.
FCJN with key = 2 becomes HELP
