Package org.bouncycastle.crypto.kems

Class SAKKEKEMExtractor

java.lang.Object
org.bouncycastle.crypto.kems.SAKKEKEMExtractor
All Implemented Interfaces:
EncapsulatedSecretExtractor
public class SAKKEKEMExtractor extends Object implements EncapsulatedSecretExtractor
Implements the receiver side of the SAKKE (Sakai-Kasahara Key Encryption) protocol as defined in RFC 6508. This class extracts the shared secret value (SSV) from encapsulated data using the receiver's private key.

The extraction process follows these steps (RFC 6508, Section 6.2.2):

  1. Parse encapsulated data into R_(b,S) and H
  2. Compute pairing result w = <R_(b,S), K_(b,S)>
  3. Recover SSV via SSV = H XOR HashToIntegerRange(w, 2^n)
  4. Validate R_(b,S) by recomputing it with derived parameters

See Also:

  • Constructor Details

    • SAKKEKEMExtractor

      public SAKKEKEMExtractor(SAKKEPrivateKeyParameters privateKey)
      Initializes the extractor with cryptographic parameters from the receiver's private key.
      Parameters:
      privateKey - The receiver's private key containing public parameters (curve, prime, generator, etc.) and the Receiver Secret Key (RSK). Must not be null.

  • Method Details

    • extractSecret

      public byte[] extractSecret(byte[] encapsulation)
      Extracts the shared secret value (SSV) from encapsulated data as per RFC 6508.
      Specified by:
      extractSecret in interface EncapsulatedSecretExtractor
      Parameters:
      encapsulation - The encapsulated data containing:
      • R_(b,S): Elliptic curve point (uncompressed format, 257 bytes)
      • H: Integer value (n/8 bytes)
      Returns:
      The extracted SSV as a byte array.
      Throws:
      IllegalStateException - If: Validation of R_(b,S) fails

    • getEncapsulationLength

      public int getEncapsulationLength()
      Description copied from interface: EncapsulatedSecretExtractor
      Return the length in bytes of the encapsulation.
      Specified by:
      getEncapsulationLength in interface EncapsulatedSecretExtractor
      Returns:
      length in bytes of an encapsulation for this parameter set.