There are three types of options in the program. All will affect the way data is encrypted and decrypted. Therefore, if any of these options is changed from their default values/adjustments, the decryption will not work even with the correct key, if not the same changes are done to the options before decryption. Because most people will use the default values, sending encrypted data to someone with non-default options used, are likely to end up with frustration for the receiver, if he or she is not well aware of these adjustments. 
Conclusion: Do not change any options if you don't have any real good reason for doing it. 
Having said this, there may be some benefits in using the options, in special cases: 
To further enhance the level of security, it is possible to insert dependencies between the encrypted bytes, so that, for example having access to the correct key but less than all encrypted data will not be sufficient for decryption of the data accessed. This may be used both to deliver extremely classified information by splitting up the encrypted data and transferring these parts using different media. It is also a major obstacle against advanced attacks to decipher encrypted data using detailed knowledge about earlier encrypted and decrypted data, even with the same key (it is also known as 'confusion' & 'diffusion' in cryptography). 
Note that if a single byte is lost or changed in the encrypted data, using interdependencies will make the decrypted data more or less unusable, because this disturbance affects more decrypted bytes than only the modified one. This is at the same time an enhancement of the protection against unauthorized access of data but also a risk for the authorized owner: if an encrypted byte happens to be changed by any reason, the decrypted data might be completely out of reach, even though the correct key is used. 
Three alternatives (depending on whether text or file is encrypted) are possible: 
  • None 
  • Some 
  • Full 
    None, means no dependencies, that is, every byte is en/de-crypted only from its position in the data stream (and the key used), but is not affected of the values of the other bytes. 
    Some, means that after some bytes have been en/de-crypted, the pseudo-random generator used, is run some steps more, depending of the newly encrypted bytes values and relative positionings, before the en/de-cryption goes on. Thus, the rest of the bytes will be dependent of the previous bytes, but not the other way around. This will make the some-version slightly slower than the none-version, but the enhance the security quite a lot. 
    All, means that changing any single byte (or more) regardless of position in the input data, will affect the encryption of all bytes, both before and after this byte. This is accomplished by applying the some-version twice, one from the beginning of the input and one from the end. Because of this, the time for this is twice of the some-version. 
    To make it impossible to setup any correspondences between any known input and output bytes, the output bytes may be relocated, using permutations. This means that the first input byte will not come out as the first encrypted byte but at another position, and so on. These permutations can be setup at different random levels and also as "Static" or "Dynamic". The input data is read in blocks and "Static" means that the same permutation is used in every block, and "Dynamic" that new permutations are generated for each block. The "Dynamic" alternative is more powerful but also takes more time. Normally, all or most bytes are relocated even with a small degree of randomness, but increasing this level will both give higher security and longer execution time. For short text messages, this extra time is normally insignificant, but for large files, these permutations might double the execution time. 
    Character Sets 
    Instead of encrypting all types of characters in a message, or a file, certain characters may be encrypted and others be left as they are. In total, there are 256 different types of characters (bytes) that all data is built up by. Every time an encryption or decryption is performed, the data is divided into two parts: a set of ENCRYPTED characters and a set of NOT encrypted characters. All characters in the latter set will be left as they are, and all characters in the former set will be encrypted to another (or the same) character in this same set. 
    Example: If the set of encrypted characters are the digits 012...9, "My PIN-code is 1234-5678" might be encrypted to: "My PIN-code is 0756-5104". Note that only the digits were encrypted, not the other characters. 
    No editor, word-processor, e-mail program or similar tools cannot handle all 256 different characters. Some are better than others, but still, there are about 80 characters that at least some of the more famous tools have problems with. Most of these characters are very special, and have no practical use in ordinary messages. To avoid "normal" characters from being encrypted into these special characters, a default set has been created, called All normal characters (default), which normally is the set of encrypted characters that should be used for text messages. Three other sets are also supplied, most for demonstration. You may create new, and modify or delete the existing sets (except for the default one). 
    To enable encrypted text to simply be selected and copied between Power Crypto and most e-mail programs, a small sacrifice had to be paid. By encrypting text this way, most of the characters in the set of encrypted characters will be encrypted, but not all. New lines (CR and LF, 'Carried Return' and 'Line Feed', as new lines are built up by) and spaces are sometimes added or removed in different ways by some e-mail programs. Also, tabs (HT) are sometimes replaced with spaces. Therefore, these characters are always replaced by some uncommon characters and restored after decryption. Space is here replaced by Þ and CR and LF are replaced by ¥, before encryption. Because these special characters are in the set of encrypted characters, these will be changed during the encryption. After decryption, these special characters are replaced by their original characters, that is, spaces and new lines, so that the plain message will be restored. Because of this, no "real" spaces or new lines exist in the encrypted data. Therefore, the program removes all possible spaces and new lines entered in the Encrypted Text window, before decryption, because these should not be there, and they have probably popped up during the copy and paste procedure of the encrypted text within the e-mail program. If this is a problem, please save the message in a file first, and then encrypt the file instead. 
    For files, there are three sets, with Every single byte as the default one. Here, there are normally not necessary to exclude any character from the encrypted set. Also, no mixing with new lines or spaces is done, as described above in the case of texts.