code: function RSASHA512() {
  
    /**
    * Sign the given string using the given key
    *
    */
    this.getSignature = function(signedInfo, signingKey) {
      var signer = crypto.createSign("RSA-SHA512")
      signer.update(signedInfo)
      var res = signer.sign(signingKey, 'base64')
      return res
    }
  
    /**
    * Verify the given signature of the given string using key
    *
    */
    this.verifySignature = function(str, key, signatureValue) {
      var verifier = crypto.createVerify("RSA-SHA512")
      verifier.update(str)
      var res = verifier.verify(key, signatureValue, 'base64')
      return res
    }
  
    this.getAlgorithmName = function() {
      return "http://www.w3.org/2001/04/xmldsig-more#rsa-sha512"
    }
  }
docs: Signature algorithm implementation