nist_curves.dart reads an uncompressed point as Go's
ecdsa.ParseUncompressedPublicKey does, and computes u1 G + u2 Q in
Jacobian coordinates with Shamir's trick, the infinity included.
ecdsa.dart is VerifyASN1: the encoding as cryptobyte reads it, r and s
in [1, n - 1] and never reduced, s above n/2 accepted, the hash cut to
the bits of the order. rsa.dart is VerifyPKCS1v15, which rebuilds the
encoding and compares it whole, and VerifyPSS with a salt of the length
of the hash, with the bytes before emLen that must be zero; and the
hashes of the table, SHA-256, SHA-384 and SHA-512 of package:crypto.
All on BigInt, exact on the VM and compiled to JavaScript, and not
constant-time: a verification sees public values only. The curve
constants are those that the vectors record from Go.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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