73 lines
3.4 KiB
Markdown
73 lines
3.4 KiB
Markdown
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secp256k1
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=========
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[](https://github.com/decred/dcrd/actions)
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[](http://copyfree.org)
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[](https://pkg.go.dev/github.com/decred/dcrd/dcrec/secp256k1/v4)
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Package secp256k1 implements optimized secp256k1 elliptic curve operations.
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This package provides an optimized pure Go implementation of elliptic curve
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cryptography operations over the secp256k1 curve as well as data structures and
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functions for working with public and private secp256k1 keys. See
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https://www.secg.org/sec2-v2.pdf for details on the standard.
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In addition, sub packages are provided to produce, verify, parse, and serialize
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ECDSA signatures and EC-Schnorr-DCRv0 (a custom Schnorr-based signature scheme
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specific to Decred) signatures. See the README.md files in the relevant sub
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packages for more details about those aspects.
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An overview of the features provided by this package are as follows:
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- Private key generation, serialization, and parsing
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- Public key generation, serialization and parsing per ANSI X9.62-1998
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- Parses uncompressed, compressed, and hybrid public keys
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- Serializes uncompressed and compressed public keys
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- Specialized types for performing optimized and constant time field operations
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- `FieldVal` type for working modulo the secp256k1 field prime
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- `ModNScalar` type for working modulo the secp256k1 group order
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- Elliptic curve operations in Jacobian projective coordinates
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- Point addition
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- Point doubling
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- Scalar multiplication with an arbitrary point
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- Scalar multiplication with the base point (group generator)
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- Point decompression from a given x coordinate
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- Nonce generation via RFC6979 with support for extra data and version
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information that can be used to prevent nonce reuse between signing algorithms
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It also provides an implementation of the Go standard library `crypto/elliptic`
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`Curve` interface via the `S256` function so that it may be used with other
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packages in the standard library such as `crypto/tls`, `crypto/x509`, and
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`crypto/ecdsa`. However, in the case of ECDSA, it is highly recommended to use
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the `ecdsa` sub package of this package instead since it is optimized
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specifically for secp256k1 and is significantly faster as a result.
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Although this package was primarily written for dcrd, it has intentionally been
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designed so it can be used as a standalone package for any projects needing to
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use optimized secp256k1 elliptic curve cryptography.
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Finally, a comprehensive suite of tests is provided to provide a high level of
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quality assurance.
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## secp256k1 use in Decred
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At the time of this writing, the primary public key cryptography in widespread
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use on the Decred network used to secure coins is based on elliptic curves
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defined by the secp256k1 domain parameters.
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## Installation and Updating
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This package is part of the `github.com/decred/dcrd/dcrec/secp256k1/v3` module.
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Use the standard go tooling for working with modules to incorporate it.
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## Examples
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* [Encryption](https://pkg.go.dev/github.com/decred/dcrd/dcrec/secp256k1/v4#example-package-EncryptDecryptMessage)
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Demonstrates encrypting and decrypting a message using a shared key derived
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through ECDHE.
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## License
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Package secp256k1 is licensed under the [copyfree](http://copyfree.org) ISC
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License.
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