initial addition of essential crypto, encoders, workflows and LLM instructions

pkg/crypto/ec/ecdsa/doc.go

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+// Copyright (c) 2020-2023 The Decred developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+// Package ecdsa provides secp256k1-optimized ECDSA signing and verification.
+//
+// This package provides data structures and functions necessary to produce and
+// verify deterministic canonical signatures in accordance with RFC6979 and
+// BIP0062, optimized specifically for the secp256k1 curve using the Elliptic Curve
+// Digital Signature Algorithm (ECDSA), as defined in FIPS 186-3.  See
+// https://www.secg.org/sec2-v2.pdf for details on the secp256k1 standard.
+//
+// It also provides functions to parse and serialize the ECDSA signatures with the
+// more strict Distinguished Encoding Rules (DER) of ISO/IEC 8825-1 and some
+// additional restrictions specific to secp256k1.
+//
+// In addition, it supports a custom "compact" signature format which allows
+// efficient recovery of the public key from a given valid signature and message
+// hash combination.
+//
+// A comprehensive suite of tests is provided to ensure proper functionality.
+//
+// # ECDSA use in Decred
+//
+// At the time of this writing, ECDSA signatures are heavily used for proving coin
+// ownership in Decred as the vast majority of transactions consist of what is
+// effectively transferring ownership of coins to a public key associated with a
+// secret key only known to the recipient of the coins along with an encumbrance
+// that requires an ECDSA signature that proves the new owner possesses the secret
+// key without actually revealing it.
+//
+// # Errors
+//
+// The errors returned by this package are of type ecdsa.Error and fully support
+// the standard library errors.Is and errors.As functions.  This allows the caller
+// to programmatically determine the specific error by examining the ErrorKind
+// field of the type asserted ecdsa.Error while still providing rich error messages
+// with contextual information.  See ErrorKind in the package documentation for a
+// full list.
+package ecdsa