B4X

Hash a Hex String

See more Encryption Examples

Demonstrates common pitfalls in hashing a hex string..

Note: This example requires Chilkat v9.5.0.70 or greater.

B4X

'  This example assumes the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim crypt As ChilkatCrypt2
crypt.Initialize("crypt")

'  We have a hex string to be SHA-256 hashed:  "b08538d832bf"
'  The result we expect to receive is "8a9f04cb1adfbd7f59c5918635f92f6c847e5b15f9828519d2fdbd6ead0918fc"

Dim strToHash As String = "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"

Dim hashValue As String = crypt.HashStringENC(strToHash)
Log(crypt.LastErrorText)
Log("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)
Log(crypt.LastErrorText)
Log("hash of 6 hex bytes: " & hashValue)

'  The result is 8A9F04CB1ADFBD7F59C5918635F92F6C847E5B15F9828519D2FDBD6EAD0918FC (which equals the hash we were expecting)