I read the technical overview of Boxcryptor but somethings is not mentioned in the description. As I know PBKDF2 hash function is as below:
DK=PBKDF2(PRF, Password, Salt, C, dklen)
DK: Derived Key
PRF: Pseudo Random Function Like SHA512
C: Number of Iterations
dklen: Length of Output or Length of DK
According to the description, for calculating the password key, Boxcryptor uses 10,000 for "C", 24 byte random data for "Salt" and HMACSHA512 for PRF. but there is no information for length of password key or the length of DK in byte. Thus, I have these questions:
1- what is the length of password key in byte?
2- what is the length of password hash in byte?
3- is the length of Salt for calculating the "password hash" 24 byte?
4- in calculating the "password key" and "password hash", Boxcryptor uses the default iterations ( 10,000 for password key & 5000 for password hash). is it possible for us to change the number of these default iterations? ( for example increase the number of iterations)
5- what is the length of "hash of password hash" which is saved in Boxcryptor's servers in byte?
Thanks in advance for answering my questions