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The title of the question says it all. I have been researching SHA-1 and most places I see it being 40 Hex Characters long which to me is 640bit. Could it not be represented just as well with only 10 hex characters 160bit = 20byte. And one hex character can represent 2 byte right? Why is it twice as long as it needs to be? What am I missing in my understanding.
And couldn't an SHA-1 be even just 5 or less characters if using Base32 or Base36 ?
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In cryptography, SHA-1 (Secure Hash Algorithm 1) is a cryptographically broken but still widely used hash function which takes an input and produces a 160-bit (20-byte) hash value known as a message digest – typically rendered as 40 hexadecimal digits.
The hash size for the SHA1 algorithm is 160 bits.
The length of a SHA1 hash is 160 bits or 20 bytes. In this application it is represented by 40 characters in hexadecimal form.
SHA-1 produces a 160-bit (20-byte) hash value known as a message digest. A SHA-1 hash value is typically rendered as a hexadecimal number, 40 digits long.
One hex character can only represent 16 different values, i.e. 4 bits. (16 = 24)
40 × 4 = 160.
And no, you need much more than 5 characters in base-36.
There are totally 2160 different SHA-1 hashes.
2160 = 1640, so this is another reason why we need 40 hex digits.
But 2160 = 36160 log362 = 3630.9482..., so you still need 31 characters using base-36.
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