It's not an uncommon scenario to require some content to pass through multiple rounds of encryption or decryption. The current, asynchronous nature of all the encrypt, decrypt, key generation functions limits this use case.

For example, if a key is required to go through 50,000 rounds of encryption before use, it would be next to impossible to perform this task with the current API without exceeding the call stack limit. Furthermore, cutting the call stack by using window.setTimeout, even with a delay of 0, dramatically increases the amount of time taken to run the same number of rounds compared to the equivalent transformation performed with an unlimited call stack, or as a series of synchronous operations.