Recently, a British Moslem (Rajib Karim) was sentenced to 30 years for attempting to use his job at British Airways to help plan, coordinate and carry out terrorist attacks. One reason Karim was caught was the refusal of his terrorist cohorts in Yemen and Bangladesh to use modern cryptography for their communications. The reason was that the modern stuff was all invented by infidels (non-Moslems). Instead the group was forced to use ancient (over 2,000 year old) single letter substitution codes. The group's implementation of this was accomplished using a spreadsheet. Unlike modern ciphers, like PGP and AES, the ancient substitution methods are easy to crack with modern decryption techniques.
A major shortcoming of Islamic radicalism is its disdain for modern, particularly non-Moslem (Western) technology. This often causes problems, like the one Karim (a computer specialist with British Airways) had with his less educated fellow terrorists in Yemen and Bangladesh. But what Karim encountered was another major problem for Islamic radicals, the fact that these groups tend to attract a disproportionate number of poorly educated recruits. The Islamic world, in general, is less educated and literate than the West, thus giving Islamic radical groups a poorly educated pool of potential recruits to begin with.
Despite this, Islamic radicals will use modern technology, but often reluctantly, with a sense of guilt, and none too effectively. Often, the Western tech is seen as a guilty pleasure. Cell phones are one example of this. Weapons, on the other hand, are more eagerly embraced. But, overall, technology, and tech knowledge, is not used by terrorists nearly as effectively as it could be.