Package com.chilkatsoft.chilkat2

Class EdDSA

java.lang.Object
com.chilkatsoft.chilkat2.ChilkatObject
com.chilkatsoft.chilkat2.EdDSA
All Implemented Interfaces:
AutoCloseable
public class EdDSA extends ChilkatObject
<section class="eddsa-summary">

Generate Ed25519 keys, sign data, verify signatures, and compute shared secrets.

Chilkat.EdDSA is the Chilkat class for Ed25519-based EdDSA operations. It can generate Ed25519 private keys, sign data contained in BinData, verify encoded signatures with public keys, and compute encoded shared secrets from compatible private/public key pairs. It supports the Ed25519, Ed25519ph, and Ed25519ctx variants, with optional context bytes supplied as a hex string when the selected variant requires them.

Generate Ed25519 keys

Create Ed25519 private keys for signing, verification, and compatible key-agreement workflows.

Sign BinData

Sign binary data directly from a Chilkat.BinData object using an Ed25519 private key.

Verify signatures

Verify encoded EdDSA signatures using the corresponding public key and the original message data.

Ed25519 variants

Use Ed25519, Ed25519ph, or Ed25519ctx depending on the protocol or interoperability requirements.

Context support

Supply optional context bytes as a hex string for workflows that use the Ed25519ctx or related context-aware signing modes.

Shared-secret output

Compute encoded shared secrets from compatible private and public key pairs for protocols that require this operation.

Common pattern: Generate or load an Ed25519 key, choose the required EdDSA variant, provide context bytes when needed, then sign or verify the BinData content. For shared-secret workflows, compute the encoded secret and pass it through the key derivation or formatting step required by the protocol.

For an extended overview, see EdDSA Class Overview.

</section>

Instances hold a native Chilkat object: close them with ChilkatObject.close() (try-with-resources) when done; an unclosed instance is freed when it becomes unreachable.

See Also:
Online reference

  • Constructor Details

    • EdDSA

      public EdDSA()
      Creates a new EdDSA object.

  • Method Details

    • getAlgorithm

      public String getAlgorithm()
      Selects the Ed25519 signature variant used by signBdENC(BinData, String, PrivateKey) and verifyBdENC(BinData, String, String, PublicKey). The default is Ed25519.

      Value Behavior Context

      Ed25519 The standard pure Ed25519 signature scheme. The complete message is signed directly by the Ed25519 algorithm. A context is not part of this variant and should be empty.

      Ed25519ctx Pure Ed25519 with domain separation supplied by a context string. The context should normally be nonempty and must match exactly during verification.

      Ed25519ph Prehash Ed25519. Chilkat first hashes the message with SHA-512 as defined for this variant. May be empty or contain up to 255 context bytes; it must match exactly during verification.

      Interoperability requirement: The signer and verifier must select the same variant. An Ed25519ph signature cannot be verified as ordinary Ed25519, even if the same key and message are used. Scope: This property selects a signing variant; it does not change the type of key generated by genEd25519Key(Prng, PrivateKey) and does not affect sharedSecretENC(PrivateKey, PublicKey, String).

      Returns:
      the value of the Algorithm property

    • setAlgorithm

      public void setAlgorithm​(String value)
      Sets the Algorithm property; see getAlgorithm().
      Parameters:
      value - the new value (not null)

    • getContext

      public String getContext()
      Gets or sets the context bytes used by the Ed25519ctx and Ed25519ph signature variants. Supply the bytes as a hexadecimal string. The default is an empty string.

      A context may contain at most 255 bytes, which corresponds to at most 510 hexadecimal characters. The same context bytes must be supplied byte-for-byte when verifying the signature. An invalid hexadecimal value or an oversized context causes the signing or verification operation to fail.

      Domain separation: A context is a public protocol label that separates signatures created for different purposes, applications, or message types. It is not a password, secret key, salt, or part of the message payload. Algorithm interaction: Use this property only when getAlgorithm() is Ed25519ctx or Ed25519ph. Standard Ed25519 does not include a context.

      Returns:
      the value of the Context property

    • setContext

      public void setContext​(String value)
      Sets the Context property; see getContext().
      Parameters:
      value - the new value (not null)

    • genEd25519Key

      public void genEd25519Key​(Prng prng, PrivateKey privKey)
      Generates a new Ed25519 key pair using prng as the source of cryptographically secure random bytes. On success, the generated private key and its corresponding public key are stored in the existing PrivateKey object passed in privKey.

      Returns true on success and false on failure. If the method fails, inspect LastErrorText for details.

      Ed25519 key size: Ed25519 key generation begins with a 32-byte private-key seed from which the public key is derived. Exported PEM, DER, JWK, or other key formats may contain additional structure and metadata, so their serialized size is not necessarily 32 bytes. Protect the private key: The generated private key can create signatures on behalf of its owner. Store it securely and disclose only the corresponding public key.

      Parameters:
      prng - the prng argument (not null)
      privKey - the privKey argument (not null)
      Throws:
      ChilkatException - if the operation fails; ChilkatException.getLastErrorText() says why

    • sharedSecretENC

      public String sharedSecretENC​(PrivateKey privkey, PublicKey pubkey, String encoding)
      Computes a 32-byte X25519 shared secret from the private key in privkey and the peer's public key in pubkey. The resulting bytes are returned as text using the binary encoding named by encoding, such as hex, hexlower, or base64.

      Each participant supplies its own private key and the other participant's public key. When Alice computes the secret from Alice's private key and Bob's public key, and Bob computes it from Bob's private key and Alice's public key, both obtain the same result.

      X25519, not an EdDSA signature operation: This method performs Curve25519 Diffie-Hellman key agreement. It is separate from the Ed25519, Ed25519ctx, and Ed25519ph signature variants, so the getAlgorithm() and getContext() properties do not apply. Do not normally use the raw secret directly: A protocol should pass the shared secret through its specified key-derivation function and should authenticate the participants' public keys. Key agreement by itself does not establish the peer's identity.

      This is a string-returning method. Check LastMethodSuccess before using the returned value; on failure, inspect LastErrorText.

      Parameters:
      privkey - the privkey argument (not null)
      pubkey - the pubkey argument (not null)
      encoding - the encoding argument (not null)
      Returns:
      the result (never null)
      Throws:
      ChilkatException - if the operation fails; ChilkatException.getLastErrorText() says why

    • signBdENC

      public String signBdENC​(BinData bd, String encoding, PrivateKey privkey)
      Creates an EdDSA signature over the exact byte sequence contained in bd, using the Ed25519 private key in privkey. The 64-byte signature is returned as text using the binary encoding named by encoding, such as hex, hexlower, or base64.

      The selected getAlgorithm() and getContext() properties determine whether the operation uses Ed25519, Ed25519ctx, or Ed25519ph. For Ed25519ph, pass the original message bytes in bd; Chilkat performs the required SHA-512 prehash as part of the Ed25519ph operation.

      Deterministic signatures: Ed25519 signatures do not require a caller-supplied per-message random number. With the same private key, message, algorithm variant, and context, the signature is deterministic. Ed25519ph is a distinct variant: It is not equivalent to hashing the message yourself and then signing that digest with ordinary Ed25519. Ed25519ph includes variant-specific domain separation.

      This is a string-returning method. Check LastMethodSuccess before using the returned value; on failure, inspect LastErrorText.

      Parameters:
      bd - the bd argument (not null)
      encoding - the encoding argument (not null)
      privkey - the privkey argument (not null)
      Returns:
      the result (never null)
      Throws:
      ChilkatException - if the operation fails; ChilkatException.getLastErrorText() says why

    • verifyBdENC

      public void verifyBdENC​(BinData bd, String encodedSig, String enocding, PublicKey pubkey)
      Verifies the encoded EdDSA signature in encodedSig against the exact byte sequence contained in bd, using the Ed25519 public key in pubkey. enocding names the binary encoding of encodedSig, such as hex, hexlower, or base64.

      The verifier must use the same getAlgorithm() and getContext() values that were used to create the signature. Any change to the message, signature, public key, algorithm variant, or context causes verification to fail.

      Returns true only when the signature is valid. Returns false for an invalid signature or an operational error, such as malformed encoded input, an unsupported encoding, or an unsuitable key. Inspect LastErrorText for diagnostic information.

      Trust remains an application decision: A valid signature proves that the message matches the supplied public key. The application must still establish that the public key belongs to the expected signer.

      Parameters:
      bd - the bd argument (not null)
      encodedSig - the encodedSig argument (not null)
      enocding - the enocding argument (not null)
      pubkey - the pubkey argument (not null)
      Throws:
      ChilkatException - if the operation fails; ChilkatException.getLastErrorText() says why