Sort of. There's less entropy per character if you know it will always be alphanumeric versus a string that of random bytes. If you take 32 bytes from /dev/ur

Sort of. There's less entropy per character if you know it will always be alphanumeric versus a string that of random bytes. If you take 32 bytes from /dev/urandom and base64 encode it, it has the same entropy as the original binary string (unless you use it in a way that will result in it being truncated). But the total entropy of the two strings is unchanged. One is just longer. In short: You're correct, but with nuance that bears stating explicitly.