# Class DigestCredentialHandlerBase

java.lang.Object
org.apache.catalina.realm.DigestCredentialHandlerBase

All Implemented Interfaces:
  `CredentialHandler`

Direct Known Subclasses:
  `MessageDigestCredentialHandler`, `SecretKeyCredentialHandler`

public abstract class DigestCredentialHandlerBase extends Object implements CredentialHandler
Base implementation for the Tomcat provided `CredentialHandler`s.

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final int`
  `DEFAULT_SALT_LENGTH`
  `protected static final StringManager`
  `sm`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `DigestCredentialHandlerBase()`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static boolean`
  `equals(byte[] b1, byte[] b2)`
  Implements byte-array equality which always compares all bytes in the array, without stopping early if any bytes do not match.
  `static boolean`
  `equals(String s1, String s2, boolean ignoreCase)`
  Implements String equality which always compares all characters in the string, without stopping early if any characters do not match.
  `abstract String`
  `getAlgorithm()`
  `protected abstract int`
  `getDefaultIterations()`
  `protected int`
  `getDefaultSaltLength()`
  `int`
  `getIterations()`
  `protected abstract Log`
  `getLog()`
  `boolean`
  `getLogInvalidStoredCredentials()`
  When checking input credentials against stored credentials will a warning message be logged if invalid stored credentials are discovered?
  `int`
  `getSaltLength()`
  `protected boolean`
  `matchesSaltIterationsEncoded(String inputCredentials, String storedCredentials)`
  Checks whether the provided credential matches the stored credential when the stored credential is in the form salt$iteration-count$credential
  `String`
  `mutate(String userCredential)`
  Generates the equivalent stored credentials for the given input credentials.
  `protected abstract String`
  `mutate(String inputCredentials, byte[] salt, int iterations)`
  Generates the equivalent stored credentials for the given input credentials, salt and iterations.
  `protected String`
  `mutate(String inputCredentials, byte[] salt, int iterations, int keyLength)`
  Generates the equivalent stored credentials for the given input credentials, salt, iterations and key length.
  `abstract void`
  `setAlgorithm(String algorithm)`
  Set the algorithm used to convert input credentials to stored credentials.
  `void`
  `setIterations(int iterations)`
  Set the number of iterations of the associated algorithm that will be used when creating a new stored credential for a given input credential.
  `void`
  `setLogInvalidStoredCredentials(boolean logInvalidStoredCredentials)`
  Set whether a warning message will be logged if invalid stored credentials are discovered while checking input credentials against stored credentials?
  `void`
  `setSaltLength(int saltLength)`
  Set the salt length that will be used when creating a new stored credential for a given input credential.

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

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

  ### Methods inherited from interface org.apache.catalina.CredentialHandler

  `matches`

- ## Field Details

  - ### sm

    protected static final StringManager sm

  - ### DEFAULT_SALT_LENGTH

    public static final int DEFAULT_SALT_LENGTH
    See Also:
      - Constant Field Values

- ## Constructor Details

  - ### DigestCredentialHandlerBase

    public DigestCredentialHandlerBase()

- ## Method Details

  - ### getIterations

    public int getIterations()
    Returns:
      the number of iterations of the associated algorithm that will be used when creating a new stored credential for a given input credential.

  - ### setIterations

    public void setIterations(int iterations)
    Set the number of iterations of the associated algorithm that will be used when creating a new stored credential for a given input credential.
    Parameters:
      `iterations` - the iterations count

  - ### getSaltLength

    public int getSaltLength()
    Returns:
      the salt length that will be used when creating a new stored credential for a given input credential.

  - ### setSaltLength

    public void setSaltLength(int saltLength)
    Set the salt length that will be used when creating a new stored credential for a given input credential.
    Parameters:
      `saltLength` - the salt length

  - ### getLogInvalidStoredCredentials

    public boolean getLogInvalidStoredCredentials()
    When checking input credentials against stored credentials will a warning message be logged if invalid stored credentials are discovered?
    Returns:
      `true` if logging will occur

  - ### setLogInvalidStoredCredentials

    public void setLogInvalidStoredCredentials(boolean logInvalidStoredCredentials)
    Set whether a warning message will be logged if invalid stored credentials are discovered while checking input credentials against stored credentials?
    Parameters:
      `logInvalidStoredCredentials` - `true` to log, the default value is `false`

  - ### mutate

    public String mutate(String userCredential)
    Description copied from interface: `CredentialHandler`
    Generates the equivalent stored credentials for the given input credentials.
    Specified by:
      `mutate` in interface `CredentialHandler`
    Parameters:
      `userCredential` - User provided credentials
    Returns:
      The equivalent stored credentials for the given input credentials

  - ### matchesSaltIterationsEncoded

    protected boolean matchesSaltIterationsEncoded(String inputCredentials, String storedCredentials)
    Checks whether the provided credential matches the stored credential when the stored credential is in the form salt$iteration-count$credential
    Parameters:
      `inputCredentials` - The input credential
      `storedCredentials` - The stored credential
    Returns:
      `true` if they match, otherwise `false`

  - ### getDefaultSaltLength

    protected int getDefaultSaltLength()
    Returns:
      the default salt length used by the `CredentialHandler`.

  - ### mutate

    protected abstract String mutate(String inputCredentials, byte[] salt, int iterations)
    Generates the equivalent stored credentials for the given input credentials, salt and iterations. If the algorithm requires a key length, the default will be used.
    Parameters:
      `inputCredentials` - User provided credentials
      `salt` - Salt, if any
      `iterations` - Number of iterations of the algorithm associated with this CredentialHandler applied to the inputCredentials to generate the equivalent stored credentials
    Returns:
      The equivalent stored credentials for the given input credentials or `null` if the generation fails

  - ### mutate

    protected String mutate(String inputCredentials, byte[] salt, int iterations, int keyLength)
    Generates the equivalent stored credentials for the given input credentials, salt, iterations and key length. The default implementation calls ignores the key length and calls `mutate(String, byte[], int)`. Subclasses that use the key length should override this method.
    Parameters:
      `inputCredentials` - User provided credentials
      `salt` - Salt, if any
      `iterations` - Number of iterations of the algorithm associated with this CredentialHandler applied to the inputCredentials to generate the equivalent stored credentials
      `keyLength` - Length of the produced digest in bits for implementations where it's applicable
    Returns:
      The equivalent stored credentials for the given input credentials or `null` if the generation fails

  - ### setAlgorithm

    public abstract void setAlgorithm(String algorithm) throws NoSuchAlgorithmException
    Set the algorithm used to convert input credentials to stored credentials.
    Parameters:
      `algorithm` - the algorithm
    Throws:
      `NoSuchAlgorithmException` - if the specified algorithm is not supported

  - ### getAlgorithm

    public abstract String getAlgorithm()
    Returns:
      the algorithm used to convert input credentials to stored credentials.

  - ### getDefaultIterations

    protected abstract int getDefaultIterations()
    Returns:
      the default number of iterations used by the `CredentialHandler`.

  - ### getLog

    protected abstract Log getLog()
    Returns:
      the logger for the CredentialHandler instance.

  - ### equals

    public static boolean equals(String s1, String s2, boolean ignoreCase)
    Implements String equality which always compares all characters in the string, without stopping early if any characters do not match.

    Note: This implementation was adapted from `MessageDigest.isEqual(byte[], byte[])` which we assume is as optimizer-defeating as possible.

    Parameters:
      `s1` - The first string to compare.
      `s2` - The second string to compare.
      `ignoreCase` - `true` if the strings should be compared without regard to case. Note that "true" here is only guaranteed to work with plain ASCII characters.
    Returns:
      `true` if the strings are equal to each other, `false` otherwise.

  - ### equals

    public static boolean equals(byte[] b1, byte[] b2)
    Implements byte-array equality which always compares all bytes in the array, without stopping early if any bytes do not match.

    Note: Implementation note: this method delegates to `MessageDigest.isEqual(byte[], byte[])` under the assumption that it provides a constant-time comparison of the bytes in the arrays. Java 7+ has such an implementation, but neither the Javadoc nor any specification requires it. Therefore, Tomcat should continue to use this method internally in case the JDK implementation changes so this method can be re-implemented properly.

    Parameters:
      `b1` - The first array to compare.
      `b2` - The second array to compare.
    Returns:
      `true` if the arrays are equal to each other, `false` otherwise.