Elliptic Curve Cryptography

This module offer cryptographic primitives based on Elliptic Curves. In particular it provides key generation and validation, signing, and verifying, for the following curves:

  • secp160r1
  • secp192r1 (NISTP192)
  • secp224r1 (NISTP224)
  • secp256r1 (NISTP256)
  • secp256k1 (used by Bitcoin)

For an awesome introduction to ECC check here. For an online ECC calculator check here

The module is based on MicroECC patched with functions to enable public key recovery (mainly for blockchain applications).

The module defines the following constants defining curves:

  • SECP160R1
  • SECP192R1
  • SECP224R1
  • SECP256R1
  • SECP256K1

Return a tuple of two elements. The first element is a byte object containing the uncompressed representation of the generated public key. The second element is a byte object containing the representation of the generated public key. curve specifies the curve to use

This function uses the random number generator provided by the VM. For real world usage and enhanced security the random number generator must be of cryptographic quality (generally implemented in hardware).

check_public_key(curve, pbkey)

Return True if pbkey (in uncompressed format) is a valid public key for curve.

derive_public_key(curve, pvkey)

Return a byte object containing the uncompressed representation of the public key matching pvkey for curve curve.

Raise ValueError if derivation is not possible.

compress_key(curve, key)

Return a compressed representation of key.

decompress_key(curve, key)

Return a uncompressed representation of key.

verify(curve, message, signature, pbkey)

Return True if signature is a valid signature for message message given curve and a public key pbkey.

sign(curve, message, pvkey, deterministic = False, recoverable = False)

Return the signature of message with pvkey for curve curve. Usually the message to sign is not the entire message but a hash of it. The deterministic parameter, if given, creates a deterministic signature according to RFC6979 . If given, the deterministic parameter must be an instance of a hash class from module crypto.hash. Deterministic signatures are not dependent on a good random number generator for their security and can therefore be used in hardware without such capabilities. If recoverable is given and True, the returned object is a tuple such that the first element is the recovery id and the second element is the signature. The recovery id is a parameter that can be used to derive the public key from a just a valid signature. For more info refer to this paper.