poly1305-mac ( message key -- tag )
Poly1305 message authentication code

Next:

poly1305-verify ( message key expected-tag -- ? )

Vocabulary
crypto.poly1305

Inputs

message	a byte-array
key	32-byte one-time key

Outputs

tag	16-byte authentication tag

Word description
Computes a Poly1305 authentication tag for the given message using a 32-byte one-time key. The key is split into two 16-byte parts: 'r' (clamped per RFC 8439) and 's'.

Warning
The key MUST be unique for each message. Never reuse a Poly1305 key.

Examples

USING: byte-arrays crypto.poly1305 ; "Hello" >byte-array B{ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 } poly1305-mac
! => B{ 205 107 36 196 87 50 35 27 200 16 3 251 167 240 226 90 }

Definition

USING: crypto.poly1305.private math ;

IN: crypto.poly1305

:: poly1305-mac ( message key -- tag )
    key split-key :> s :> r poly1305-prime :> p message r p
    poly1305-process s + num>tag ;