Encrypt 4 digit codes using cypher (based on BIP-39)

I want to convert my 24 word BIP 39 pass phrase into 4 digit codes. Then encrypt those 4 digits using a cypher.

Does anyone know or recommend any cyphers for encrypting a 4 digit number?

I think a shift cypher would be easiest

Basically you take the alphabet and match a number to it. Then you pick a random number and shift it over all the letters.number-substitution-cypher ![number-substitution-cypher|600x365]

So if you wanted to encode the word


The BIP 39 is 139

So we could just add a random number to each digit like 4

so 1 becomes 5
3 becomes 7
9 becomes 4

574 = element (on bip 39)

then to decrypt subtract 4 from each number 574


Zoo is 2048
so you may want to add the 10th digit

6 4 8 2