Package org.bouncycastle.crypto.signers

## Class ECNRSigner

- java.lang.Object
- - org.bouncycastle.crypto.signers.ECNRSigner

- All Implemented Interfaces:
    `DSA`, `DSAExt`

      public class ECNRSigner
      extends java.lang.Object
      implements DSAExt

  EC-NR as described in IEEE 1363-2000 - a signature algorithm for Elliptic Curve which also offers message recovery.

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `ECNRSigner()` |

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `java.math.BigInteger[]` | `generateSignature​(byte[] digest)` | generate a signature for the given message using the key we were initialised with.
    `java.math.BigInteger` | `getOrder()` | Get the order of the group that the r, s values in signatures belong to.
    `byte[]` | `getRecoveredMessage​(java.math.BigInteger r, java.math.BigInteger s)` | Returns the data used for the signature generation, assuming the public key passed to init() is correct.
    `void` | `init​(boolean forSigning, CipherParameters param)` | Initialise the signer.
    `boolean` | `verifySignature​(byte[] digest, java.math.BigInteger r, java.math.BigInteger s)` | return true if the value r and s represent a signature for the message passed in.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### ECNRSigner

          public ECNRSigner()

  - ### Method Detail

    - #### init

          public void init​(boolean forSigning,
                           CipherParameters param)

      Initialise the signer.
      Specified by:
        `init` in interface `DSA`
      Parameters:
        `forSigning` - true if we are generating a signature, false for verification or if we want to use the signer for message recovery.
        `param` - key parameters for signature generation.

    - #### getOrder

          public java.math.BigInteger getOrder()

      Description copied from interface: `DSAExt`
      Get the order of the group that the r, s values in signatures belong to.
      Specified by:
        `getOrder` in interface `DSAExt`

    - #### generateSignature

          public java.math.BigInteger[] generateSignature​(byte[] digest)

      generate a signature for the given message using the key we were initialised with. Generally, the order of the curve should be at least as long as the hash of the message of interest, and with ECNR it *must* be at least as long.
      Specified by:
        `generateSignature` in interface `DSA`
      Parameters:
        `digest` - the digest to be signed.
      Returns:
        two big integers representing the r and s values respectively.
      Throws:
        `DataLengthException` - if the digest is longer than the key allows

    - #### verifySignature

          public boolean verifySignature​(byte[] digest,
                                         java.math.BigInteger r,
                                         java.math.BigInteger s)

      return true if the value r and s represent a signature for the message passed in. Generally, the order of the curve should be at least as long as the hash of the message of interest, and with ECNR, it *must* be at least as long. But just in case the signer applied mod(n) to the longer digest, this implementation will apply mod(n) during verification.
      Specified by:
        `verifySignature` in interface `DSA`
      Parameters:
        `digest` - the digest to be verified.
        `r` - the r value of the signature.
        `s` - the s value of the signature.
      Throws:
        `DataLengthException` - if the digest is longer than the key allows

    - #### getRecoveredMessage

          public byte[] getRecoveredMessage​(java.math.BigInteger r,
                                            java.math.BigInteger s)

      Returns the data used for the signature generation, assuming the public key passed to init() is correct.
      Returns:
        null if r and s are not valid.