I am new to cryptography and have a question about a use of Vigenere cipher in the case of small strings. I'd like to encrypt keywords that are smaller than 10 characters.
If I use Vigenere separately for each keyword I can have a key longer than 10 characters, and making each string impossible to break (if I use a different key each time).
But I would also like to be able to sort the encrypted keywords to avoid processing them in the clear (sorting is necessary which made me think about a polyalphabetic cipher. I have hundreds of keywords).
For this, I would need all the keywords to be encrypted with the same key. And now I have an issue with the length of the key. Because I will never use more than 10 characters of my key. And somebody could concatenate all the keywords.
I have read that encrypting a vigenere several times doesn't provide more security. That the only way to make vigenere more secure is to extend the key. In this case extending the key is of no use, as I have small strings (so only the first chars of the key will be used).
Do you see any technique that could be used to improve the security, while still providing sorting capabilities?