class Matter::Crypto::Spake2p

Overview

SPAKE2+ implementation for Matter protocol Based on https://datatracker.ietf.org/doc/html/draft-bar-cfrg-spake2plus

SPAKE2+ is a password-authenticated key exchange protocol used during Matter commissioning This is a wrapper around the spake2_plus library configured for Matter's requirements

Defined in:

matter/crypto/spake2p.cr

Constant Summary

CRYPTO_GROUP_SIZE_BYTES = 32
CRYPTO_W_SIZE_BYTES = CRYPTO_GROUP_SIZE_BYTES + 8
Log = ::Log.for("matter.spake2p")
M_HEX = "02886e2f97ace46e55ba9dd7242579f2993b64e16ef3dcab95afd497333d8fa12f"

M and N constants for P-256 curve From SPAKE2+ specification

N_HEX = "03d8bbd6c639c62937b04d997f38c3770719c629d7014d49a24b4f98baa1292b49"

Constructors

Class Method Summary

Instance Method Summary

Constructor Detail

def self.create(crypto : CryptoBase, context : Bytes, w0 : BigInt) : Spake2p #

Create SPAKE2+ instance with context and w0


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def self.new(crypto : CryptoBase, context : Bytes, random : BigInt, w0 : BigInt) #

Alternative constructor for testing with specific random values This allows test vectors to specify exact random values for reproducibility


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def self.new(protocol : SPAKE2Plus::Protocol) #

Constructor for integration with SPAKE2Plus library


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Class Method Detail

def self.compute_passcode_verifier(crypto : CryptoBase, params : PbkdfParameters, pin : UInt32) : Bytes #

Compute the passcode verifier used by AdministratorCommissioning OpenCommissioningWindow.

This is 97 bytes: w0 (32-byte big-endian) || L (65-byte uncompressed EC point).


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def self.compute_w0_l(crypto : CryptoBase, params : PbkdfParameters, pin : UInt32) : W0L #

Compute w0 and L from PIN L = w1 * G (where G is the generator point)


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def self.compute_w0_w1(crypto : CryptoBase, params : PbkdfParameters, pin : UInt32) : W0W1 #

Compute w0 and w1 from PIN using PBKDF2


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Instance Method Detail

def compute_secret_and_verifiers_from_x(l : Bytes, x : Bytes, y : Bytes) : SecretAndVerifiers #

Compute shared secret and verifiers from X (verifier side)


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def compute_secret_and_verifiers_from_y(w1 : BigInt, x : Bytes, y : Bytes) : SecretAndVerifiers #

Compute shared secret and verifiers from Y (prover side)


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def compute_x : Bytes #

Compute X = xG + w0M (prover computes this)


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def compute_y : Bytes #

Compute Y = yG + w0N (verifier computes this)


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def context : Bytes #

Expose protocol properties


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def random : BigInt #

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def w0 : BigInt #

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