github.com/zmap/zlint@v1.1.0/lints/lint_dsa_unique_correct_representation.go (about)

     1  package lints
     2  
     3  /*
     4   * ZLint Copyright 2018 Regents of the University of Michigan
     5   *
     6   * Licensed under the Apache License, Version 2.0 (the "License"); you may not
     7   * use this file except in compliance with the License. You may obtain a copy
     8   * of the License at http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
    13   * implied. See the License for the specific language governing
    14   * permissions and limitations under the License.
    15   */
    16  
    17  import (
    18  	"crypto/dsa"
    19  	"math/big"
    20  
    21  	"github.com/zmap/zcrypto/x509"
    22  	"github.com/zmap/zlint/util"
    23  )
    24  
    25  type dsaUniqueCorrectRepresentation struct{}
    26  
    27  func (l *dsaUniqueCorrectRepresentation) Initialize() error {
    28  	return nil
    29  }
    30  
    31  func (l *dsaUniqueCorrectRepresentation) CheckApplies(c *x509.Certificate) bool {
    32  	return c.PublicKeyAlgorithm == x509.DSA
    33  }
    34  
    35  func (l *dsaUniqueCorrectRepresentation) Execute(c *x509.Certificate) *LintResult {
    36  	dsaKey, ok := c.PublicKey.(*dsa.PublicKey)
    37  	if !ok {
    38  		return &LintResult{Status: NA}
    39  	}
    40  	// Verify that 2 ≤ y ≤ p-2.
    41  	two := big.NewInt(2)
    42  	pMinusTwo := big.NewInt(0)
    43  	pMinusTwo.Sub(dsaKey.P, two)
    44  	if two.Cmp(dsaKey.Y) > 0 || dsaKey.Y.Cmp(pMinusTwo) > 0 {
    45  		return &LintResult{Status: Error}
    46  	}
    47  	return &LintResult{Status: Pass}
    48  }
    49  
    50  func init() {
    51  	RegisterLint(&Lint{
    52  		Name:          "e_dsa_unique_correct_representation",
    53  		Description:   "DSA: Public key value has the unique correct representation in the field, and that the key has the correct order in the subgroup",
    54  		Citation:      "BRs: 6.1.6",
    55  		Source:        CABFBaselineRequirements,
    56  		EffectiveDate: util.CABEffectiveDate,
    57  		Lint:          &dsaUniqueCorrectRepresentation{},
    58  	})
    59  }