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(Excel) Hash a Hex StringDemonstrates common pitfalls in hashing a hex string.. Note: This example requires Chilkat v9.5.0.70 or greater.
' This example assumes the Chilkat API to have been previously unlocked. ' See Global Unlock Sample for sample code. Dim crypt As Chilkat.Crypt2 Set crypt = Chilkat.NewCrypt2 ' We have a hex string to be SHA-256 hashed: "b08538d832bf" ' The result we expect to receive is "8a9f04cb1adfbd7f59c5918635f92f6c847e5b15f9828519d2fdbd6ead0918fc" strToHash = "b08538d832bf" ' How do we get this result? ' The 1st question to be answered is: What bytes are getting hashed? ' There are two possibilities: ' 1) Hash 12 bytes, namely the us-ascii values for 'b', '0', '8', '5', .... 'b', 'f' ' or ' 2) Hash 6 bytes: 0xb0, 0x85, ... 0xbf ' ' This is how to hash the 12 us-ascii byte values: ' The Charset property defines the byte representation of the string passed to the hash algorithm: crypt.Charset = "us-ascii" ' The EncodingMode property defines the binary encoding (hex, base64, etc.) of the hash returned as an encoded string. crypt.EncodingMode = "hex" crypt.HashAlgorithm = "sha256" hashValue = crypt.HashStringENC(strToHash) Debug.Print crypt.LastErrorText Debug.Print "hash of 12 us-ascii bytes: "; hashValue ' The result is: 327F2B33A0F0580D09840B0D7CEE54514CA33E9A (not what we were hoping). ' ------------------------------------------- ' This is how to hash the 6 bytes ' ' "hex" is not an actual character encoding. It's a special value to be used to tell Chilkat to hex decode ' the string and pass the decoded bytes to the hash algorithm... ' Note: This example requires Chilkat v9.5.0.70 or greater for the "hex" Charset to work properly. crypt.Charset = "hex" ' The EncodingMode and HashAlgorithm remain the same.. hashValue = crypt.HashStringENC(strToHash) Debug.Print crypt.LastErrorText Debug.Print "hash of 6 hex bytes: "; hashValue ' The result is 8A9F04CB1ADFBD7F59C5918635F92F6C847E5B15F9828519D2FDBD6EAD0918FC (which equals the hash we were expecting) |
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