ed25519_sign.dart signs as crypto_sign of TweetNaCl in its JavaScript
port, with the SHA-512 of package:crypto: the field of curve25519.dart,
whose arithmetic is private there, copied with the product as a loop, and
modL over 64 limbs of 8 bits in a Float64List, with floor divisions in
place of the shifts of TweetNaCl, exact on the VM and on the web. The
secret scalar and the nonce never meet a BigInt or a branch; neither
platform promises constant time, and the values are wiped as a best
effort.
authorkey.dart ports package authorkey of datekeys-go: AuthorKey with
generate, fromSeed, publicKey, sign, clear and secret, and a toString
that hides it; authorPublicString, parseAuthorPublic and
parseAuthorSecret, also on the bytes of a Go string; marshalAuthorKey;
encryptAuthorKey, scrypt with logN 16 through ScryptRecipient and
ageEncrypt of stage 6a; and readAuthorKey, through the age reader with a
maximum work factor of 16, whose lines are those of bufio.Scanner and
strings.TrimSpace. Every error has the text of Go, with the sets of
go_unicode.dart for the case of a string and the spaces of a line. A
cleared key refuses every use, where Go would give the values of a key of
zeros.
tool/authorkey_go_vectors.go writes test/vectors/authorkey.json: the
signatures of crypto/ed25519 over lines of sign.input (RFC 8032 tests
1, 2, 3 and 1024), TEST SHA(abc), seeded seeds and messages up to 1 MiB
and other public keys; the scalars of math/big; and Generate, Encrypt,
ParsePublic, ParseSecret and Read of authorkey with each text, while
crypto/rand reads the keystream of SeededRandomSource. Dart writes the
same bytes and gives the same texts in every case; authorkey.g.dart, a
part of it, runs also in Node.js.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
