Today, is it possible to decipher a pseudo-random encryption of text?

That depends on how it was encrypted and how much data is available. If we’re talking about a one-time pad with a series of psuedorandom values as a key, then decryption may be possible if there is a large enough sample to find the pattern in the key. With todays pseudoranom number generators, you would need a very big sample.

On the other hand, if there are multiple samples of ciphertext encrypted with the same pseudorandom key, then the problem becomes much easier.

For best results, use a one-time pad with random bits generated by some natural phenomenon. My favorite is radioactive decay.

Not sure what you mean by “pseudo-random”. Do you mean something like an encrypting function with a flawed random number generator? That’s a flaw in the encrypting, to be sure, but it may or may not be enough to allow a successful ciphertext-only attack.

One case where it would be: a common technique to “seed” a random number generator is to use the current time. If the attacker knows approximately what time you seeded the generator, he may be able to recover that random number–a bad thing, if you used it (say) for a key.

Does that help?

pesudorandom means that the ‘random’ numbers are created by a determanistic math formula that just happens to make numbers that seem random. its what basicly every single personal computer on earth uses to make random numbers.

Decryptiuon of any encrypted text is higly dependent on having sufficient text to analyize, i.e. one very long document or severl shorter docments encryped with the same scheme.

I could give you an infinite number of documents encrypted via nothing more than a single XOR operation with a truly random, non-repeating one-time pad, and you could not decrypt it ever.

The decryptability of something depends on either the weakness of the algorithm, the non-randomness of the key, or the repeat use of a single key, and in all cases, sufficient data to analyze.