Key Entropy Size

Formula

Total entropy size = (Number of keys) x (Entropy size per key)
Key Size (bytes) Entropy Size Per Key (bytes)
16 20
32 (size of an AES-256 key) 40
64 80
256 290
1,024 (1 KiB) 1,140 (1.11 KiB)
10,240 (10 KiB) 11,380 (11.11 KiB)
102,400 (100 KiB) 113,780 (111.11 KiB)
1,048,576 (1 MiB) 1,165,090 (1.11 MiB)
10,485,760 (10 MiB) 11,650,850 (11.1 MiB)

Example 1:

To generate (or to sync) 100 of AES-256 keys, the entropy size will be

100 keys x 40 bytes/key = 4,000 bytes = 3.91 KiB

Example 2:

To generate (or to sync) 100 of 256-byte OTP keys, the entropy size will be

100 keys x 290 bytes/key = 29,000 bytes = 28.32 KiB

Example 3:

To generate (or to sync) 100 of AES-256 keys and 200 of 256-byte OTP keys, the entropy size will be

( 100 keys x 40 bytes/key ) + ( 200 keys x 290 bytes/key ) = 62,000 bytes = 60.55 KiB

Example 4:

An entropy quota of 25 MiB allows you to generate (or to sync)

( 20 MiB / 40 bytes/key ) = ( 20,971,152 bytes / 40 bytes/key ) = 65,536 keys of 32-bytes