Class RSABlindSignatureParameters

java.lang.Object
org.bouncycastle.crypto.params.RSABlindSignatureParameters
public final class RSABlindSignatureParameters extends Object
Variant parameters for the RSA Blind Signature Scheme with Appendix (RSABSSA) defined in RFC 9474. Each variant fixes a content digest, an EMSA-PSS salt length, and whether the message-preparation step is identity or randomised (32-byte prefix per RFC 9474 sec. 4.1). The four named variants from RFC 9474 sec. 5 are exposed as constants; SHA-384 with MGF1(SHA-384) is the only hash profile named by the RFC.

The randomised variants are RECOMMENDED by RFC 9474 sec. 5; the deterministic variants are useful for interop with callers that must derive the prepared message from msg alone.

  • Field Details

    • RANDOMIZED_PREFIX_LEN

      public static final int RANDOMIZED_PREFIX_LEN
      Length in bytes of the random prefix prepended to msg by PrepareRandomize (RFC 9474 sec. 4.1).
      See Also:

    • RSABSSA_SHA384_PSS_RANDOMIZED

      public static final RSABlindSignatureParameters RSABSSA_SHA384_PSS_RANDOMIZED
      RSABSSA-SHA384-PSS-Randomized — SHA-384, 48-byte salt, 32-byte random prefix. RECOMMENDED by RFC 9474 sec. 5.

    • RSABSSA_SHA384_PSSZERO_RANDOMIZED

      public static final RSABlindSignatureParameters RSABSSA_SHA384_PSSZERO_RANDOMIZED
      RSABSSA-SHA384-PSSZERO-Randomized — SHA-384, empty salt, 32-byte random prefix. RECOMMENDED by RFC 9474 sec. 5; the empty salt makes the signature deterministic given a fixed prepared message, while the prefix preserves blindness.

    • RSABSSA_SHA384_PSS_DETERMINISTIC

      public static final RSABlindSignatureParameters RSABSSA_SHA384_PSS_DETERMINISTIC
      RSABSSA-SHA384-PSS-Deterministic — SHA-384, 48-byte salt, identity preparation. Use only when the caller has another source of message unlinkability; see RFC 9474 sec. 7.3.

    • RSABSSA_SHA384_PSSZERO_DETERMINISTIC

      public static final RSABlindSignatureParameters RSABSSA_SHA384_PSSZERO_DETERMINISTIC
      RSABSSA-SHA384-PSSZERO-Deterministic — SHA-384, empty salt, identity preparation. RFC 9474 sec. 5 warns this combination yields fully deterministic signatures; use only when the caller actively wants that.

  • Method Details

    • getName

      public String getName()
      Return the RFC 9474 sec. 5 variant name (e.g. RSABSSA-SHA384-PSS-Randomized).

    • getSaltLength

      public int getSaltLength()
      Return the EMSA-PSS salt length, in bytes.

    • isRandomized

      public boolean isRandomized()
      Return true if the Prepare step prepends a fresh 32-byte random prefix (RFC 9474 sec. 4.1 — PrepareRandomize); false if Prepare is the identity (RFC 9474 sec. 4.1 — PrepareIdentity).

    • createDigest

      public Digest createDigest()
      Return a fresh Digest instance for the variant's content hash (SHA-384 for every variant defined in RFC 9474 sec. 5).