Cryptography

Cryptography(Rogue, 1)
Ability: Intelligence
Modifier: Special
Possession of this proficiency allows the character to create and break codes and ciphers. Reading/writing is required in order to learn this skill. Multiple picks of this proficiency are often very helpful. Codes and ciphers fall into four levels of difficulty (equivalent to the number of slots of “cryptography” taken by the person that does the encryption). Their specific requirements are as follows:

Level of Difficulty	Breaking time	Check Modifier
1	8 Hours	+1
2	1 Day	0
3	1 Week	-1
4	1 Month	-2

The person encrypting the text can use a difficulty level no higher than the level of cryptography skill they possesses. The base breaking time is the unit of time that a person must spend to have any chance of “breaking” the code. Each day of code‐ breaking must be 8 hours of uninterrupted thought or the period must be begun anew.
  The check modifier is an additional bonus/penalty applied to breaking a code that is dependent on its difficulty only. The DM may choose to add more modifiers because of the length of the text or successive failures. Codes/ciphers can only be broken by a person familiar with the language that the normal text is in.
  If encrypted documents are to be used for general communications, both the encrypter and decrypter must know the key. The impracticality of changing keys frequently is the only thing that tends to keep codes in use for long enough that breaking them becomes worthwhile.