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      1 package gov.nist.javax.sip.clientauthutils;
      2 
      3 import gov.nist.core.StackLogger;
      4 
      5 import java.security.MessageDigest;
      6 import java.security.NoSuchAlgorithmException;
      7 
      8 /**
      9  * The class takes standard Http Authentication details and returns a response according to the
     10  * MD5 algorithm
     11  *
     12  * @author Emil Ivov
     13  */
     14 
     15 public class MessageDigestAlgorithm {
     16     /**
     17      * Calculates an http authentication response in accordance with rfc2617.
     18      * <p>
     19      *
     20      * @param algorithm a string indicating a pair of algorithms (MD5 (default), or MD5-sess) used
     21      *        to produce the digest and a checksum.
     22      * @param hashUserNameRealmPasswd MD5 hash of (username:realm:password)
     23      * @param nonce_value A server-specified data string provided in the challenge.
     24      * @param cnonce_value an optional client-chosen value whose purpose is to foil chosen
     25      *        plaintext attacks.
     26      * @param method the SIP method of the request being challenged.
     27      * @param digest_uri_value the value of the "uri" directive on the Authorization header in the
     28      *        request.
     29      * @param entity_body the entity-body
     30      * @param qop_value Indicates what "quality of protection" the client has applied to the
     31      *        message.
     32      * @param nc_value the hexadecimal count of the number of requests (including the current
     33      *        request) that the client has sent with the nonce value in this request.
     34      * @return a digest response as defined in rfc2617
     35      * @throws NullPointerException in case of incorrectly null parameters.
     36      */
     37 
     38     static String calculateResponse(String algorithm, String hashUserNameRealmPasswd,
     39             String nonce_value, String nc_value, String cnonce_value,
     40             String method, String digest_uri_value, String entity_body, String qop_value,
     41             StackLogger stackLogger)  {
     42         if (stackLogger.isLoggingEnabled()) {
     43             stackLogger.logDebug("trying to authenticate using : " + algorithm + ", "+
     44                     hashUserNameRealmPasswd + ", " + nonce_value + ", "
     45                     + nc_value + ", " + cnonce_value + ", " + method + ", " + digest_uri_value
     46                     + ", " + entity_body + ", " + qop_value);
     47         }
     48 
     49         if (hashUserNameRealmPasswd == null || method == null
     50                 || digest_uri_value == null || nonce_value == null)
     51             throw new NullPointerException(
     52                     "Null parameter to MessageDigestAlgorithm.calculateResponse()");
     53 
     54         // The following follows closely the algorithm for generating a response
     55         // digest as specified by rfc2617
     56 
     57         if (cnonce_value == null || cnonce_value.length() == 0)
     58                 throw new NullPointerException(
     59                         "cnonce_value may not be absent for MD5-Sess algorithm.");
     60 
     61 
     62         String A2 = null;
     63         if (qop_value == null || qop_value.trim().length() == 0
     64                 || qop_value.trim().equalsIgnoreCase("auth")) {
     65             A2 = method + ":" + digest_uri_value;
     66         } else {
     67             if (entity_body == null)
     68                 entity_body = "";
     69             A2 = method + ":" + digest_uri_value + ":" + H(entity_body);
     70         }
     71 
     72         String request_digest = null;
     73 
     74         if (cnonce_value != null && qop_value != null && nc_value != null
     75                 && (qop_value.equalsIgnoreCase("auth") || qop_value.equalsIgnoreCase("auth-int")))
     76 
     77         {
     78             request_digest = KD(hashUserNameRealmPasswd, nonce_value + ":" + nc_value + ":" + cnonce_value + ":"
     79                     + qop_value + ":" + H(A2));
     80 
     81         } else {
     82             request_digest = KD(hashUserNameRealmPasswd, nonce_value + ":" + H(A2));
     83         }
     84 
     85         return request_digest;
     86 
     87 
     88     }
     89 
     90     /**
     91      * Calculates an http authentication response in accordance with rfc2617.
     92      * <p>
     93      *
     94      * @param algorithm a string indicating a pair of algorithms (MD5 (default), or MD5-sess) used
     95      *        to produce the digest and a checksum.
     96      * @param username_value username_value (see rfc2617)
     97      * @param realm_value A string that has been displayed to the user in order to determine the
     98      *        context of the username and password to use.
     99      * @param passwd the password to encode in the challenge response.
    100      * @param nonce_value A server-specified data string provided in the challenge.
    101      * @param cnonce_value an optional client-chosen value whose purpose is to foil chosen
    102      *        plaintext attacks.
    103      * @param method the SIP method of the request being challenged.
    104      * @param digest_uri_value the value of the "uri" directive on the Authorization header in the
    105      *        request.
    106      * @param entity_body the entity-body
    107      * @param qop_value Indicates what "quality of protection" the client has applied to the
    108      *        message.
    109      * @param nc_value the hexadecimal count of the number of requests (including the current
    110      *        request) that the client has sent with the nonce value in this request.
    111      * @return a digest response as defined in rfc2617
    112      * @throws NullPointerException in case of incorrectly null parameters.
    113      */
    114     static String calculateResponse(String algorithm, String username_value, String realm_value,
    115             String passwd, String nonce_value, String nc_value, String cnonce_value,
    116             String method, String digest_uri_value, String entity_body, String qop_value,
    117             StackLogger stackLogger) {
    118         if (stackLogger.isLoggingEnabled()) {
    119             stackLogger.logDebug("trying to authenticate using : " + algorithm + ", "
    120                     + username_value + ", " + realm_value + ", "
    121                     + (passwd != null && passwd.trim().length() > 0) + ", " + nonce_value + ", "
    122                     + nc_value + ", " + cnonce_value + ", " + method + ", " + digest_uri_value
    123                     + ", " + entity_body + ", " + qop_value);
    124         }
    125 
    126         if (username_value == null || realm_value == null || passwd == null || method == null
    127                 || digest_uri_value == null || nonce_value == null)
    128             throw new NullPointerException(
    129                     "Null parameter to MessageDigestAlgorithm.calculateResponse()");
    130 
    131         // The following follows closely the algorithm for generating a response
    132         // digest as specified by rfc2617
    133         String A1 = null;
    134 
    135         if (algorithm == null || algorithm.trim().length() == 0
    136                 || algorithm.trim().equalsIgnoreCase("MD5")) {
    137             A1 = username_value + ":" + realm_value + ":" + passwd;
    138         } else {
    139             if (cnonce_value == null || cnonce_value.length() == 0)
    140                 throw new NullPointerException(
    141                         "cnonce_value may not be absent for MD5-Sess algorithm.");
    142 
    143             A1 = H(username_value + ":" + realm_value + ":" + passwd) + ":" + nonce_value + ":"
    144                     + cnonce_value;
    145         }
    146 
    147         String A2 = null;
    148         if (qop_value == null || qop_value.trim().length() == 0
    149                 || qop_value.trim().equalsIgnoreCase("auth")) {
    150             A2 = method + ":" + digest_uri_value;
    151         } else {
    152             if (entity_body == null)
    153                 entity_body = "";
    154             A2 = method + ":" + digest_uri_value + ":" + H(entity_body);
    155         }
    156 
    157         String request_digest = null;
    158 
    159         if (cnonce_value != null && qop_value != null && nc_value != null
    160                 && (qop_value.equalsIgnoreCase("auth") || qop_value.equalsIgnoreCase("auth-int")))
    161 
    162         {
    163             request_digest = KD(H(A1), nonce_value + ":" + nc_value + ":" + cnonce_value + ":"
    164                     + qop_value + ":" + H(A2));
    165 
    166         } else {
    167             request_digest = KD(H(A1), nonce_value + ":" + H(A2));
    168         }
    169 
    170         return request_digest;
    171     }
    172 
    173     /**
    174      * Defined in rfc 2617 as H(data) = MD5(data);
    175      *
    176      * @param data data
    177      * @return MD5(data)
    178      */
    179     private static String H(String data) {
    180         try {
    181             MessageDigest digest = MessageDigest.getInstance("MD5");
    182 
    183             return toHexString(digest.digest(data.getBytes()));
    184         } catch (NoSuchAlgorithmException ex) {
    185             // shouldn't happen
    186             throw new RuntimeException("Failed to instantiate an MD5 algorithm", ex);
    187         }
    188     }
    189 
    190     /**
    191      * Defined in rfc 2617 as KD(secret, data) = H(concat(secret, ":", data))
    192      *
    193      * @param data data
    194      * @param secret secret
    195      * @return H(concat(secret, ":", data));
    196      */
    197     private static String KD(String secret, String data) {
    198         return H(secret + ":" + data);
    199     }
    200 
    201     // the following code was copied from the NIST-SIP instant
    202     // messenger (its author is Olivier Deruelle). Thanks for making it public!
    203     /**
    204      * to hex converter
    205      */
    206     private static final char[] toHex = {
    207         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
    208     };
    209 
    210     /**
    211      * Converts b[] to hex string.
    212      *
    213      * @param b the bte array to convert
    214      * @return a Hex representation of b.
    215      */
    216     private static String toHexString(byte b[]) {
    217         int pos = 0;
    218         char[] c = new char[b.length * 2];
    219         for (int i = 0; i < b.length; i++) {
    220             c[pos++] = toHex[(b[i] >> 4) & 0x0F];
    221             c[pos++] = toHex[b[i] & 0x0f];
    222         }
    223         return new String(c);
    224     }
    225 }
    226