how to compact a char-numeric variable string

[rohitamitpathak]

I am working for encryption and decryption using rsa algorithm ,and adding my own concept in rsa, after rsa and padding i m getting a string like-
100011234A12300A12A231A234A981A
for different input output string is increase... Is there any technique by use of that i can compact this string [ then easy store in database and retrieve and convert into real form when required]

[Narue]

and adding my own concept in rsa

Which, unless you're quite a skilled cryptanalyst, will probably ruin the algorithm's strength.Is there any technique by use of that i can compact this string
A typical way to compact cipher text is converting it to a base-64 string. This has the dual benefit of making the cipher text both smaller and widely portable.

[Momerath]

Does your string only contain the values 0-9 and the letter A? If so, you only need 4 bits to store that, which means you can pack 2 characters in each byte, halving the amount of storage required.

[rohitamitpathak]

Does your string only contain the values 0-9 and the letter A? If so, you only need 4 bits to store that, which means you can pack 2 characters in each byte, halving the amount of storage required.

yes i have only numbers and A, how to implement your logic? give me some hint