B4X

Poly1305 MAC

See more Encryption Examples

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. B4X

Dim success As Boolean = False

'  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")

'  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.
Dim keyHex As String = "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0"
success = crypt.SetMacKeyEncoded(keyHex, "hex")

Dim plainText As String = "'Twas brillig, and the slithy toves" & Chr(10) & "Did gyre and gimble in the wabe:" & Chr(10) & "All mimsy were the borogoves," & Chr(10) & "And the mome raths outgrabe."

'  The computed tag should match the Tag shown below.
'  (Note: hexidecimal encoding is case insensitive.)
Dim encTag As String = crypt.MacStringENC(plainText)
Log(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...|...b