(Excel) Poly1305 MAC

Demonstrates the Poly1305 Message Authentication Code. (Introduced in Chilkat v9.5.0.55) This example duplicates the results of Test Vector #4 for Poly1305 in RFC 7539.

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' 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

' Set the MAC algorithm to poly1305
crypt.MacAlgorithm = "poly1305"

' EncodingMode specifies the encoding of the output for
' encryption, and the input for decryption.
' Valid modes are (case insensitive) "Base64", "modBase64", "Base32", "Base58", "UU", 
' "QP" (for quoted-printable), "URL" (for url-encoding), "Hex", 
' "Q", "B", "url_oauth", "url_rfc1738", "url_rfc2396", and "url_rfc3986".
crypt.EncodingMode = "hex"

' Poly1305 always uses a 32-byte (256-bit) MAC key.

keyHex = "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0"

success = crypt.SetMacKeyEncoded(keyHex,"hex")


plainText = "'Twas brillig, and the slithy toves" & vbLf & "Did gyre and gimble in the wabe:" & vbLf & "All mimsy were the borogoves," & vbLf & "And the mome raths outgrabe."

' The computed tag should match the Tag shown below.
' (Note: hexidecimal encoding is case insensitive.)

encTag = crypt.MacStringENC(plainText)
Debug.Print encTag

' Here is the Test Vector data copied from RFC 7539

'  Test Vector #4:
'  ==============
' 
'  One-time Poly1305 Key:
'  000  1c 92 40 a5 eb 55 d3 8a f3 33 88 86 04 f6 b5 f0  ..@..U...3......
'  016  47 39 17 c1 40 2b 80 09 9d ca 5c bc 20 70 75 c0  G9..@+....\. pu.
' 
'  Text to MAC:
'  000  27 54 77 61 73 20 62 72 69 6c 6c 69 67 2c 20 61  'Twas brillig, a
'  016  6e 64 20 74 68 65 20 73 6c 69 74 68 79 20 74 6f  nd the slithy to
'  032  76 65 73 0a 44 69 64 20 67 79 72 65 20 61 6e 64  ves.Did gyre and
'  048  20 67 69 6d 62 6c 65 20 69 6e 20 74 68 65 20 77   gimble in the w
'  064  61 62 65 3a 0a 41 6c 6c 20 6d 69 6d 73 79 20 77  abe:.All mimsy w
'  080  65 72 65 20 74 68 65 20 62 6f 72 6f 67 6f 76 65  ere the borogove
'  096  73 2c 0a 41 6e 64 20 74 68 65 20 6d 6f 6d 65 20  s,.And the mome
'  112  72 61 74 68 73 20 6f 75 74 67 72 61 62 65 2e     raths outgrabe.
' 
'  Tag:
'  000  45 41 66 9a 7e aa ee 61 e7 08 dc 7c bc c5 eb 62  EAf.~..a...|...