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Crate p256

Crate p256 

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§RustCrypto: NIST P-256 (secp256r1) elliptic curve

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Pure Rust implementation of the NIST P-256 (a.k.a. secp256r1, prime256v1) elliptic curve with support for ECDH, ECDSA signing/verification, and general purpose curve arithmetic support implemented in terms of traits from the elliptic-curve crate.

Documentation

§⚠️ Security Warning

The elliptic curve arithmetic contained in this crate has never been independently audited!

This crate has been designed with the goal of ensuring that secret-dependent operations are performed in constant time (using the subtle crate and constant-time formulas). However, it has not been thoroughly assessed to ensure that generated assembly is constant time on common CPU architectures.

USE AT YOUR OWN RISK!

§Supported Algorithms

§PKCS#8 Key Encoding

PKCS#8 is a private key format with support for multiple algorithms. It can be encoded as binary DER or text PEM.

You can recognize PEM encoded PKCS#8 private keys because they do not have an algorithm name in the type label, e.g.:

-----BEGIN PRIVATE KEY-----

PKCS#8 support is gated under the pkcs8 feature. The pem feature, which is enabled by default, adds PEM decoding and also enables pkcs8.

The same pattern is used by the other curve crates in this repository which re-export pkcs8.

The following traits can be used to decode/encode secret and public keys as PKCS#8/SPKI. Note that pkcs8 is re-exported from p256 when the pkcs8 feature is enabled:

For private keys, SecretKey::from_der and SecretKey::from_pem provide convenience methods which can decode PKCS#8 keys. Use the trait methods above when the input is expected to be specifically PKCS#8.

§Example

use p256::SecretKey;

// WARNING: Do not hardcode private keys in your source code. This is for demonstration purposes only.
let pem = r#"-----BEGIN PRIVATE KEY-----
MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgaWJBcVYaYzQN4OfY
afKgVJJVjhoEhotqn4VKhmeIGI2hRANCAAQcrP+1Xy8s79idies3SyaBFSRSgC3u
oJkWBoE32DnPf8SBpESSME1+9mrBF77+g6jQjxVfK1L59hjdRHApBI4P
-----END PRIVATE KEY-----"#;
let secret_key = SecretKey::from_pem(pem)?;

§About NIST P-256

NIST P-256 is a Weierstrass curve specified in SP 800-186: Recommendations for Discrete Logarithm-based Cryptography: Elliptic Curve Domain Parameters.

Also known as prime256v1 (ANSI X9.62) and secp256r1 (SECG), it’s included in the US National Security Agency’s “Suite B” and is widely used in protocols like TLS and the associated X.509 PKI.

§License

All crates licensed under either of

at your option.

§Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

§serde support

When the serde feature of this crate is enabled, Serialize and Deserialize are impl’d for the following types:

Please see type-specific documentation for more information.

Re-exports§

pub use elliptic_curve;
pub use elliptic_curve::pkcs8;pkcs8
pub use hash2curve;hash2curve

Modules§

ecdhecdh
Elliptic Curve Diffie-Hellman (Ephemeral) Support.
ecdsaecdsa-core
Elliptic Curve Digital Signature Algorithm (ECDSA)
test_vectorstest-vectors
secp256r1 test vectors.

Structs§

NistP256
NIST P-256 elliptic curve.
Scalararithmetic
Scalars are elements in the finite field modulo n.

Type Aliases§

AffinePointarithmetic
Elliptic curve point in affine coordinates.
BlindedScalararithmetic
Blinded scalar.
CompressedPoint
Compressed SEC1-encoded NIST P-256 curve point.
FieldBytes
NIST P-256 field element serialized as bytes.
NonZeroScalararithmetic
Non-zero NIST P-256 scalar field element.
ProjectivePointarithmetic
Elliptic curve point in projective coordinates.
PublicKeyarithmetic
NIST P-256 public key.
Sec1Point
NIST P-256 SEC1 encoded point.
SecretKey
NIST P-256 secret key.
U32
U256
256-bit unsigned big integer.