vauth: Moved the DIGEST authentication code to the new vauth directory

4 files changed, 1479 insertions, 0 deletions

diff --git a/lib/vauth/digest.c b/lib/vauth/digest.c
new file mode 100644
index 000000000..ee8646b86
--- /dev/null
+++ b/lib/vauth/digest.c
@@ -0,0 +1,881 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * RFC2831 DIGEST-MD5 authentication
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#if !defined(CURL_DISABLE_CRYPTO_AUTH)
+
+#include <curl/curl.h>
+
+#include "vauth/vauth.h"
+#include "vauth/digest.h"
+#include "urldata.h"
+#include "curl_base64.h"
+#include "curl_hmac.h"
+#include "curl_md5.h"
+#include "vtls/vtls.h"
+#include "warnless.h"
+#include "strtok.h"
+#include "rawstr.h"
+#include "non-ascii.h" /* included for Curl_convert_... prototypes */
+#include "curl_printf.h"
+
+/* The last #include files should be: */
+#include "curl_memory.h"
+#include "memdebug.h"
+
+#if !defined(USE_WINDOWS_SSPI)
+#define DIGEST_QOP_VALUE_AUTH             (1 << 0)
+#define DIGEST_QOP_VALUE_AUTH_INT         (1 << 1)
+#define DIGEST_QOP_VALUE_AUTH_CONF        (1 << 2)
+
+#define DIGEST_QOP_VALUE_STRING_AUTH      "auth"
+#define DIGEST_QOP_VALUE_STRING_AUTH_INT  "auth-int"
+#define DIGEST_QOP_VALUE_STRING_AUTH_CONF "auth-conf"
+
+/* The CURL_OUTPUT_DIGEST_CONV macro below is for non-ASCII machines.
+   It converts digest text to ASCII so the MD5 will be correct for
+   what ultimately goes over the network.
+*/
+#define CURL_OUTPUT_DIGEST_CONV(a, b) \
+  result = Curl_convert_to_network(a, (char *)b, strlen((const char*)b)); \
+  if(result) { \
+    free(b); \
+    return result; \
+  }
+#endif /* !USE_WINDOWS_SSPI */
+
+bool Curl_sasl_digest_get_pair(const char *str, char *value, char *content,
+                               const char **endptr)
+{
+  int c;
+  bool starts_with_quote = FALSE;
+  bool escape = FALSE;
+
+  for(c = DIGEST_MAX_VALUE_LENGTH - 1; (*str && (*str != '=') && c--); )
+    *value++ = *str++;
+  *value = 0;
+
+  if('=' != *str++)
+    /* eek, no match */
+    return FALSE;
+
+  if('\"' == *str) {
+    /* This starts with a quote so it must end with one as well! */
+    str++;
+    starts_with_quote = TRUE;
+  }
+
+  for(c = DIGEST_MAX_CONTENT_LENGTH - 1; *str && c--; str++) {
+    switch(*str) {
+    case '\\':
+      if(!escape) {
+        /* possibly the start of an escaped quote */
+        escape = TRUE;
+        *content++ = '\\'; /* Even though this is an escape character, we still
+                              store it as-is in the target buffer */
+        continue;
+      }
+      break;
+
+    case ',':
+      if(!starts_with_quote) {
+        /* This signals the end of the content if we didn't get a starting
+           quote and then we do "sloppy" parsing */
+        c = 0; /* the end */
+        continue;
+      }
+      break;
+
+    case '\r':
+    case '\n':
+      /* end of string */
+      c = 0;
+      continue;
+
+    case '\"':
+      if(!escape && starts_with_quote) {
+        /* end of string */
+        c = 0;
+        continue;
+      }
+      break;
+    }
+
+    escape = FALSE;
+    *content++ = *str;
+  }
+
+  *content = 0;
+  *endptr = str;
+
+  return TRUE;
+}
+
+#if !defined(USE_WINDOWS_SSPI)
+/* Convert md5 chunk to RFC2617 (section 3.1.3) -suitable ascii string*/
+static void sasl_digest_md5_to_ascii(unsigned char *source, /* 16 bytes */
+                                     unsigned char *dest) /* 33 bytes */
+{
+  int i;
+  for(i = 0; i < 16; i++)
+    snprintf((char *) &dest[i * 2], 3, "%02x", source[i]);
+}
+
+/* Perform quoted-string escaping as described in RFC2616 and its errata */
+static char *sasl_digest_string_quoted(const char *source)
+{
+  char *dest, *d;
+  const char *s = source;
+  size_t n = 1; /* null terminator */
+
+  /* Calculate size needed */
+  while(*s) {
+    ++n;
+    if(*s == '"' || *s == '\\') {
+      ++n;
+    }
+    ++s;
+  }
+
+  dest = malloc(n);
+  if(dest) {
+    s = source;
+    d = dest;
+    while(*s) {
+      if(*s == '"' || *s == '\\') {
+        *d++ = '\\';
+      }
+      *d++ = *s++;
+    }
+    *d = 0;
+  }
+
+  return dest;
+}
+
+/* Retrieves the value for a corresponding key from the challenge string
+ * returns TRUE if the key could be found, FALSE if it does not exists
+ */
+static bool sasl_digest_get_key_value(const char *chlg,
+                                      const char *key,
+                                      char *value,
+                                      size_t max_val_len,
+                                      char end_char)
+{
+  char *find_pos;
+  size_t i;
+
+  find_pos = strstr(chlg, key);
+  if(!find_pos)
+    return FALSE;
+
+  find_pos += strlen(key);
+
+  for(i = 0; *find_pos && *find_pos != end_char && i < max_val_len - 1; ++i)
+    value[i] = *find_pos++;
+  value[i] = '\0';
+
+  return TRUE;
+}
+
+static CURLcode sasl_digest_get_qop_values(const char *options, int *value)
+{
+  char *tmp;
+  char *token;
+  char *tok_buf;
+
+  /* Initialise the output */
+  *value = 0;
+
+  /* Tokenise the list of qop values. Use a temporary clone of the buffer since
+     strtok_r() ruins it. */
+  tmp = strdup(options);
+  if(!tmp)
+    return CURLE_OUT_OF_MEMORY;
+
+  token = strtok_r(tmp, ",", &tok_buf);
+  while(token != NULL) {
+    if(Curl_raw_equal(token, DIGEST_QOP_VALUE_STRING_AUTH))
+      *value |= DIGEST_QOP_VALUE_AUTH;
+    else if(Curl_raw_equal(token, DIGEST_QOP_VALUE_STRING_AUTH_INT))
+      *value |= DIGEST_QOP_VALUE_AUTH_INT;
+    else if(Curl_raw_equal(token, DIGEST_QOP_VALUE_STRING_AUTH_CONF))
+      *value |= DIGEST_QOP_VALUE_AUTH_CONF;
+
+    token = strtok_r(NULL, ",", &tok_buf);
+  }
+
+  free(tmp);
+
+  return CURLE_OK;
+}
+
+/*
+ * sasl_decode_digest_md5_message()
+ *
+ * This is used internally to decode an already encoded DIGEST-MD5 challenge
+ * message into the seperate attributes.
+ *
+ * Parameters:
+ *
+ * chlg64  [in]     - The base64 encoded challenge message.
+ * nonce   [in/out] - The buffer where the nonce will be stored.
+ * nlen    [in]     - The length of the nonce buffer.
+ * realm   [in/out] - The buffer where the realm will be stored.
+ * rlen    [in]     - The length of the realm buffer.
+ * alg     [in/out] - The buffer where the algorithm will be stored.
+ * alen    [in]     - The length of the algorithm buffer.
+ * qop     [in/out] - The buffer where the qop-options will be stored.
+ * qlen    [in]     - The length of the qop buffer.
+ *
+ * Returns CURLE_OK on success.
+ */
+static CURLcode sasl_decode_digest_md5_message(const char *chlg64,
+                                               char *nonce, size_t nlen,
+                                               char *realm, size_t rlen,
+                                               char *alg, size_t alen,
+                                               char *qop, size_t qlen)
+{
+  CURLcode result = CURLE_OK;
+  unsigned char *chlg = NULL;
+  size_t chlglen = 0;
+  size_t chlg64len = strlen(chlg64);
+
+  /* Decode the base-64 encoded challenge message */
+  if(chlg64len && *chlg64 != '=') {
+    result = Curl_base64_decode(chlg64, &chlg, &chlglen);
+    if(result)
+      return result;
+  }
+
+  /* Ensure we have a valid challenge message */
+  if(!chlg)
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  /* Retrieve nonce string from the challenge */
+  if(!sasl_digest_get_key_value((char *) chlg, "nonce=\"", nonce, nlen, '\"')) {
+    free(chlg);
+    return CURLE_BAD_CONTENT_ENCODING;
+  }
+
+  /* Retrieve realm string from the challenge */
+  if(!sasl_digest_get_key_value((char *) chlg, "realm=\"", realm, rlen, '\"')) {
+    /* Challenge does not have a realm, set empty string [RFC2831] page 6 */
+    strcpy(realm, "");
+  }
+
+  /* Retrieve algorithm string from the challenge */
+  if(!sasl_digest_get_key_value((char *) chlg, "algorithm=", alg, alen, ',')) {
+    free(chlg);
+    return CURLE_BAD_CONTENT_ENCODING;
+  }
+
+  /* Retrieve qop-options string from the challenge */
+  if(!sasl_digest_get_key_value((char *) chlg, "qop=\"", qop, qlen, '\"')) {
+    free(chlg);
+    return CURLE_BAD_CONTENT_ENCODING;
+  }
+
+  free(chlg);
+
+  return CURLE_OK;
+}
+
+/*
+ * Curl_sasl_create_digest_md5_message()
+ *
+ * This is used to generate an already encoded DIGEST-MD5 response message
+ * ready for sending to the recipient.
+ *
+ * Parameters:
+ *
+ * data    [in]     - The session handle.
+ * chlg64  [in]     - The base64 encoded challenge message.
+ * userp   [in]     - The user name.
+ * passdwp [in]     - The user's password.
+ * service [in]     - The service type such as www, smtp, pop or imap.
+ * outptr  [in/out] - The address where a pointer to newly allocated memory
+ *                    holding the result will be stored upon completion.
+ * outlen  [out]    - The length of the output message.
+ *
+ * Returns CURLE_OK on success.
+ */
+CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
+                                             const char *chlg64,
+                                             const char *userp,
+                                             const char *passwdp,
+                                             const char *service,
+                                             char **outptr, size_t *outlen)
+{
+  CURLcode result = CURLE_OK;
+  size_t i;
+  MD5_context *ctxt;
+  char *response = NULL;
+  unsigned char digest[MD5_DIGEST_LEN];
+  char HA1_hex[2 * MD5_DIGEST_LEN + 1];
+  char HA2_hex[2 * MD5_DIGEST_LEN + 1];
+  char resp_hash_hex[2 * MD5_DIGEST_LEN + 1];
+  char nonce[64];
+  char realm[128];
+  char algorithm[64];
+  char qop_options[64];
+  int qop_values;
+  char cnonce[33];
+  unsigned int entropy[4];
+  char nonceCount[] = "00000001";
+  char method[]     = "AUTHENTICATE";
+  char qop[]        = DIGEST_QOP_VALUE_STRING_AUTH;
+  char *spn         = NULL;
+
+  /* Decode the challange message */
+  result = sasl_decode_digest_md5_message(chlg64, nonce, sizeof(nonce),
+                                          realm, sizeof(realm),
+                                          algorithm, sizeof(algorithm),
+                                          qop_options, sizeof(qop_options));
+  if(result)
+    return result;
+
+  /* We only support md5 sessions */
+  if(strcmp(algorithm, "md5-sess") != 0)
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  /* Get the qop-values from the qop-options */
+  result = sasl_digest_get_qop_values(qop_options, &qop_values);
+  if(result)
+    return result;
+
+  /* We only support auth quality-of-protection */
+  if(!(qop_values & DIGEST_QOP_VALUE_AUTH))
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  /* Generate 16 bytes of random data */
+  entropy[0] = Curl_rand(data);
+  entropy[1] = Curl_rand(data);
+  entropy[2] = Curl_rand(data);
+  entropy[3] = Curl_rand(data);
+
+  /* Convert the random data into a 32 byte hex string */
+  snprintf(cnonce, sizeof(cnonce), "%08x%08x%08x%08x",
+           entropy[0], entropy[1], entropy[2], entropy[3]);
+
+  /* So far so good, now calculate A1 and H(A1) according to RFC 2831 */
+  ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
+  if(!ctxt)
+    return CURLE_OUT_OF_MEMORY;
+
+  Curl_MD5_update(ctxt, (const unsigned char *) userp,
+                  curlx_uztoui(strlen(userp)));
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+  Curl_MD5_update(ctxt, (const unsigned char *) realm,
+                  curlx_uztoui(strlen(realm)));
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+  Curl_MD5_update(ctxt, (const unsigned char *) passwdp,
+                  curlx_uztoui(strlen(passwdp)));
+  Curl_MD5_final(ctxt, digest);
+
+  ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
+  if(!ctxt)
+    return CURLE_OUT_OF_MEMORY;
+
+  Curl_MD5_update(ctxt, (const unsigned char *) digest, MD5_DIGEST_LEN);
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+  Curl_MD5_update(ctxt, (const unsigned char *) nonce,
+                  curlx_uztoui(strlen(nonce)));
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+  Curl_MD5_update(ctxt, (const unsigned char *) cnonce,
+                  curlx_uztoui(strlen(cnonce)));
+  Curl_MD5_final(ctxt, digest);
+
+  /* Convert calculated 16 octet hex into 32 bytes string */
+  for(i = 0; i < MD5_DIGEST_LEN; i++)
+    snprintf(&HA1_hex[2 * i], 3, "%02x", digest[i]);
+
+  /* Generate our SPN */
+  spn = Curl_sasl_build_spn(service, realm);
+  if(!spn)
+    return CURLE_OUT_OF_MEMORY;
+
+  /* Calculate H(A2) */
+  ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
+  if(!ctxt) {
+    free(spn);
+
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  Curl_MD5_update(ctxt, (const unsigned char *) method,
+                  curlx_uztoui(strlen(method)));
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+  Curl_MD5_update(ctxt, (const unsigned char *) spn,
+                  curlx_uztoui(strlen(spn)));
+  Curl_MD5_final(ctxt, digest);
+
+  for(i = 0; i < MD5_DIGEST_LEN; i++)
+    snprintf(&HA2_hex[2 * i], 3, "%02x", digest[i]);
+
+  /* Now calculate the response hash */
+  ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
+  if(!ctxt) {
+    free(spn);
+
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  Curl_MD5_update(ctxt, (const unsigned char *) HA1_hex, 2 * MD5_DIGEST_LEN);
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+  Curl_MD5_update(ctxt, (const unsigned char *) nonce,
+                  curlx_uztoui(strlen(nonce)));
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+
+  Curl_MD5_update(ctxt, (const unsigned char *) nonceCount,
+                  curlx_uztoui(strlen(nonceCount)));
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+  Curl_MD5_update(ctxt, (const unsigned char *) cnonce,
+                  curlx_uztoui(strlen(cnonce)));
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+  Curl_MD5_update(ctxt, (const unsigned char *) qop,
+                  curlx_uztoui(strlen(qop)));
+  Curl_MD5_update(ctxt, (const unsigned char *) ":", 1);
+
+  Curl_MD5_update(ctxt, (const unsigned char *) HA2_hex, 2 * MD5_DIGEST_LEN);
+  Curl_MD5_final(ctxt, digest);
+
+  for(i = 0; i < MD5_DIGEST_LEN; i++)
+    snprintf(&resp_hash_hex[2 * i], 3, "%02x", digest[i]);
+
+  /* Generate the response */
+  response = aprintf("username=\"%s\",realm=\"%s\",nonce=\"%s\","
+                     "cnonce=\"%s\",nc=\"%s\",digest-uri=\"%s\",response=%s,"
+                     "qop=%s",
+                     userp, realm, nonce,
+                     cnonce, nonceCount, spn, resp_hash_hex, qop);
+  free(spn);
+  if(!response)
+    return CURLE_OUT_OF_MEMORY;
+
+  /* Base64 encode the response */
+  result = Curl_base64_encode(data, response, 0, outptr, outlen);
+
+  free(response);
+
+  return result;
+}
+
+/*
+ * Curl_sasl_decode_digest_http_message()
+ *
+ * This is used to decode a HTTP DIGEST challenge message into the seperate
+ * attributes.
+ *
+ * Parameters:
+ *
+ * chlg    [in]     - The challenge message.
+ * digest  [in/out] - The digest data struct being used and modified.
+ *
+ * Returns CURLE_OK on success.
+ */
+CURLcode Curl_sasl_decode_digest_http_message(const char *chlg,
+                                              struct digestdata *digest)
+{
+  bool before = FALSE; /* got a nonce before */
+  bool foundAuth = FALSE;
+  bool foundAuthInt = FALSE;
+  char *token = NULL;
+  char *tmp = NULL;
+
+  /* If we already have received a nonce, keep that in mind */
+  if(digest->nonce)
+    before = TRUE;
+
+  /* Clean up any former leftovers and initialise to defaults */
+  Curl_sasl_digest_cleanup(digest);
+
+  for(;;) {
+    char value[DIGEST_MAX_VALUE_LENGTH];
+    char content[DIGEST_MAX_CONTENT_LENGTH];
+
+    /* Pass all additional spaces here */
+    while(*chlg && ISSPACE(*chlg))
+      chlg++;
+
+    /* Extract a value=content pair */
+    if(Curl_sasl_digest_get_pair(chlg, value, content, &chlg)) {
+      if(Curl_raw_equal(value, "nonce")) {
+        free(digest->nonce);
+        digest->nonce = strdup(content);
+        if(!digest->nonce)
+          return CURLE_OUT_OF_MEMORY;
+      }
+      else if(Curl_raw_equal(value, "stale")) {
+        if(Curl_raw_equal(content, "true")) {
+          digest->stale = TRUE;
+          digest->nc = 1; /* we make a new nonce now */
+        }
+      }
+      else if(Curl_raw_equal(value, "realm")) {
+        free(digest->realm);
+        digest->realm = strdup(content);
+        if(!digest->realm)
+          return CURLE_OUT_OF_MEMORY;
+      }
+      else if(Curl_raw_equal(value, "opaque")) {
+        free(digest->opaque);
+        digest->opaque = strdup(content);
+        if(!digest->opaque)
+          return CURLE_OUT_OF_MEMORY;
+      }
+      else if(Curl_raw_equal(value, "qop")) {
+        char *tok_buf;
+        /* Tokenize the list and choose auth if possible, use a temporary
+           clone of the buffer since strtok_r() ruins it */
+        tmp = strdup(content);
+        if(!tmp)
+          return CURLE_OUT_OF_MEMORY;
+
+        token = strtok_r(tmp, ",", &tok_buf);
+        while(token != NULL) {
+          if(Curl_raw_equal(token, DIGEST_QOP_VALUE_STRING_AUTH)) {
+            foundAuth = TRUE;
+          }
+          else if(Curl_raw_equal(token, DIGEST_QOP_VALUE_STRING_AUTH_INT)) {
+            foundAuthInt = TRUE;
+          }
+          token = strtok_r(NULL, ",", &tok_buf);
+        }
+
+        free(tmp);
+
+        /* Select only auth or auth-int. Otherwise, ignore */
+        if(foundAuth) {
+          free(digest->qop);
+          digest->qop = strdup(DIGEST_QOP_VALUE_STRING_AUTH);
+          if(!digest->qop)
+            return CURLE_OUT_OF_MEMORY;
+        }
+        else if(foundAuthInt) {
+          free(digest->qop);
+          digest->qop = strdup(DIGEST_QOP_VALUE_STRING_AUTH_INT);
+          if(!digest->qop)
+            return CURLE_OUT_OF_MEMORY;
+        }
+      }
+      else if(Curl_raw_equal(value, "algorithm")) {
+        free(digest->algorithm);
+        digest->algorithm = strdup(content);
+        if(!digest->algorithm)
+          return CURLE_OUT_OF_MEMORY;
+
+        if(Curl_raw_equal(content, "MD5-sess"))
+          digest->algo = CURLDIGESTALGO_MD5SESS;
+        else if(Curl_raw_equal(content, "MD5"))
+          digest->algo = CURLDIGESTALGO_MD5;
+        else
+          return CURLE_BAD_CONTENT_ENCODING;
+      }
+      else {
+        /* Unknown specifier, ignore it! */
+      }
+    }
+    else
+      break; /* We're done here */
+
+    /* Pass all additional spaces here */
+    while(*chlg && ISSPACE(*chlg))
+      chlg++;
+
+    /* Allow the list to be comma-separated */
+    if(',' == *chlg)
+      chlg++;
+  }
+
+  /* We had a nonce since before, and we got another one now without
+     'stale=true'. This means we provided bad credentials in the previous
+     request */
+  if(before && !digest->stale)
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  /* We got this header without a nonce, that's a bad Digest line! */
+  if(!digest->nonce)
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  return CURLE_OK;
+}
+
+/*
+ * Curl_sasl_create_digest_http_message()
+ *
+ * This is used to generate a HTTP DIGEST response message ready for sending
+ * to the recipient.
+ *
+ * Parameters:
+ *
+ * data    [in]     - The session handle.
+ * userp   [in]     - The user name.
+ * passdwp [in]     - The user's password.
+ * request [in]     - The HTTP request.
+ * uripath [in]     - The path of the HTTP uri.
+ * digest  [in/out] - The digest data struct being used and modified.
+ * outptr  [in/out] - The address where a pointer to newly allocated memory
+ *                    holding the result will be stored upon completion.
+ * outlen  [out]    - The length of the output message.
+ *
+ * Returns CURLE_OK on success.
+ */
+CURLcode Curl_sasl_create_digest_http_message(struct SessionHandle *data,
+                                              const char *userp,
+                                              const char *passwdp,
+                                              const unsigned char *request,
+                                              const unsigned char *uripath,
+                                              struct digestdata *digest,
+                                              char **outptr, size_t *outlen)
+{
+  CURLcode result;
+  unsigned char md5buf[16]; /* 16 bytes/128 bits */
+  unsigned char request_digest[33];
+  unsigned char *md5this;
+  unsigned char ha1[33];    /* 32 digits and 1 zero byte */
+  unsigned char ha2[33];    /* 32 digits and 1 zero byte */
+  char cnoncebuf[33];
+  char *cnonce = NULL;
+  size_t cnonce_sz = 0;
+  char *userp_quoted;
+  char *response = NULL;
+  char *tmp = NULL;
+
+  if(!digest->nc)
+    digest->nc = 1;
+
+  if(!digest->cnonce) {
+    snprintf(cnoncebuf, sizeof(cnoncebuf), "%08x%08x%08x%08x",
+             Curl_rand(data), Curl_rand(data),
+             Curl_rand(data), Curl_rand(data));
+
+    result = Curl_base64_encode(data, cnoncebuf, strlen(cnoncebuf),
+                                &cnonce, &cnonce_sz);
+    if(result)
+      return result;
+
+    digest->cnonce = cnonce;
+  }
+
+  /*
+    If the algorithm is "MD5" or unspecified (which then defaults to MD5):
+
+      A1 = unq(username-value) ":" unq(realm-value) ":" passwd
+
+    If the algorithm is "MD5-sess" then:
+
+      A1 = H( unq(username-value) ":" unq(realm-value) ":" passwd ) ":"
+           unq(nonce-value) ":" unq(cnonce-value)
+  */
+
+  md5this = (unsigned char *)
+    aprintf("%s:%s:%s", userp, digest->realm, passwdp);
+  if(!md5this)
+    return CURLE_OUT_OF_MEMORY;
+
+  CURL_OUTPUT_DIGEST_CONV(data, md5this); /* convert on non-ASCII machines */
+  Curl_md5it(md5buf, md5this);
+  free(md5this);
+  sasl_digest_md5_to_ascii(md5buf, ha1);
+
+  if(digest->algo == CURLDIGESTALGO_MD5SESS) {
+    /* nonce and cnonce are OUTSIDE the hash */
+    tmp = aprintf("%s:%s:%s", ha1, digest->nonce, digest->cnonce);
+    if(!tmp)
+      return CURLE_OUT_OF_MEMORY;
+
+    CURL_OUTPUT_DIGEST_CONV(data, tmp); /* Convert on non-ASCII machines */
+    Curl_md5it(md5buf, (unsigned char *) tmp);
+    free(tmp);
+    sasl_digest_md5_to_ascii(md5buf, ha1);
+  }
+
+  /*
+    If the "qop" directive's value is "auth" or is unspecified, then A2 is:
+
+      A2 = Method ":" digest-uri-value
+
+    If the "qop" value is "auth-int", then A2 is:
+
+      A2 = Method ":" digest-uri-value ":" H(entity-body)
+
+    (The "Method" value is the HTTP request method as specified in section
+    5.1.1 of RFC 2616)
+  */
+
+  md5this = (unsigned char *) aprintf("%s:%s", request, uripath);
+
+  if(digest->qop && Curl_raw_equal(digest->qop, "auth-int")) {
+    /* We don't support auth-int for PUT or POST at the moment.
+       TODO: replace md5 of empty string with entity-body for PUT/POST */
+    unsigned char *md5this2 = (unsigned char *)
+      aprintf("%s:%s", md5this, "d41d8cd98f00b204e9800998ecf8427e");
+    free(md5this);
+    md5this = md5this2;
+  }
+
+  if(!md5this)
+    return CURLE_OUT_OF_MEMORY;
+
+  CURL_OUTPUT_DIGEST_CONV(data, md5this); /* convert on non-ASCII machines */
+  Curl_md5it(md5buf, md5this);
+  free(md5this);
+  sasl_digest_md5_to_ascii(md5buf, ha2);
+
+  if(digest->qop) {
+    md5this = (unsigned char *) aprintf("%s:%s:%08x:%s:%s:%s",
+                                        ha1,
+                                        digest->nonce,
+                                        digest->nc,
+                                        digest->cnonce,
+                                        digest->qop,
+                                        ha2);
+  }
+  else {
+    md5this = (unsigned char *) aprintf("%s:%s:%s",
+                                        ha1,
+                                        digest->nonce,
+                                        ha2);
+  }
+
+  if(!md5this)
+    return CURLE_OUT_OF_MEMORY;
+
+  CURL_OUTPUT_DIGEST_CONV(data, md5this); /* convert on non-ASCII machines */
+  Curl_md5it(md5buf, md5this);
+  free(md5this);
+  sasl_digest_md5_to_ascii(md5buf, request_digest);
+
+  /* For test case 64 (snooped from a Mozilla 1.3a request)
+
+     Authorization: Digest username="testuser", realm="testrealm", \
+     nonce="1053604145", uri="/64", response="c55f7f30d83d774a3d2dcacf725abaca"
+
+     Digest parameters are all quoted strings.  Username which is provided by
+     the user will need double quotes and backslashes within it escaped.  For
+     the other fields, this shouldn't be an issue.  realm, nonce, and opaque
+     are copied as is from the server, escapes and all.  cnonce is generated
+     with web-safe characters.  uri is already percent encoded.  nc is 8 hex
+     characters.  algorithm and qop with standard values only contain web-safe
+     characters.
+  */
+  userp_quoted = sasl_digest_string_quoted(userp);
+  if(!userp_quoted)
+    return CURLE_OUT_OF_MEMORY;
+
+  if(digest->qop) {
+    response = aprintf("username=\"%s\", "
+                       "realm=\"%s\", "
+                       "nonce=\"%s\", "
+                       "uri=\"%s\", "
+                       "cnonce=\"%s\", "
+                       "nc=%08x, "
+                       "qop=%s, "
+                       "response=\"%s\"",
+                       userp_quoted,
+                       digest->realm,
+                       digest->nonce,
+                       uripath,
+                       digest->cnonce,
+                       digest->nc,
+                       digest->qop,
+                       request_digest);
+
+    if(Curl_raw_equal(digest->qop, "auth"))
+      digest->nc++; /* The nc (from RFC) has to be a 8 hex digit number 0
+                       padded which tells to the server how many times you are
+                       using the same nonce in the qop=auth mode */
+  }
+  else {
+    response = aprintf("username=\"%s\", "
+                       "realm=\"%s\", "
+                       "nonce=\"%s\", "
+                       "uri=\"%s\", "
+                       "response=\"%s\"",
+                       userp_quoted,
+                       digest->realm,
+                       digest->nonce,
+                       uripath,
+                       request_digest);
+  }
+  free(userp_quoted);
+  if(!response)
+    return CURLE_OUT_OF_MEMORY;
+
+  /* Add the optional fields */
+  if(digest->opaque) {
+    /* Append the opaque */
+    tmp = aprintf("%s, opaque=\"%s\"", response, digest->opaque);
+    free(response);
+    if(!tmp)
+      return CURLE_OUT_OF_MEMORY;
+
+    response = tmp;
+  }
+
+  if(digest->algorithm) {
+    /* Append the algorithm */
+    tmp = aprintf("%s, algorithm=\"%s\"", response, digest->algorithm);
+    free(response);
+    if(!tmp)
+      return CURLE_OUT_OF_MEMORY;
+
+    response = tmp;
+  }
+
+  /* Return the output */
+  *outptr = response;
+  *outlen = strlen(response);
+
+  return CURLE_OK;
+}
+
+/*
+ * Curl_sasl_digest_cleanup()
+ *
+ * This is used to clean up the digest specific data.
+ *
+ * Parameters:
+ *
+ * digest    [in/out] - The digest data struct being cleaned up.
+ *
+ */
+void Curl_sasl_digest_cleanup(struct digestdata *digest)
+{
+  Curl_safefree(digest->nonce);
+  Curl_safefree(digest->cnonce);
+  Curl_safefree(digest->realm);
+  Curl_safefree(digest->opaque);
+  Curl_safefree(digest->qop);
+  Curl_safefree(digest->algorithm);
+
+  digest->nc = 0;
+  digest->algo = CURLDIGESTALGO_MD5; /* default algorithm */
+  digest->stale = FALSE; /* default means normal, not stale */
+}
+#endif  /* !USE_WINDOWS_SSPI */
+
+#endif  /* CURL_DISABLE_CRYPTO_AUTH */
diff --git a/lib/vauth/digest.h b/lib/vauth/digest.h
new file mode 100644
index 000000000..4c58f002c
--- /dev/null
+++ b/lib/vauth/digest.h
@@ -0,0 +1,43 @@
+#ifndef HEADER_CURL_DIGEST_H
+#define HEADER_CURL_DIGEST_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+#include <curl/curl.h>
+
+#if !defined(CURL_DISABLE_CRYPTO_AUTH)
+
+#define DIGEST_MAX_VALUE_LENGTH           256
+#define DIGEST_MAX_CONTENT_LENGTH         1024
+
+enum {
+  CURLDIGESTALGO_MD5,
+  CURLDIGESTALGO_MD5SESS
+};
+
+/* This is used to extract the realm from a challenge message */
+bool Curl_sasl_digest_get_pair(const char *str, char *value, char *content,
+                               const char **endptr);
+
+#endif
+
+#endif /* HEADER_CURL_DIGEST_H */
diff --git a/lib/vauth/digest_sspi.c b/lib/vauth/digest_sspi.c
new file mode 100644
index 000000000..802c02b54
--- /dev/null
+++ b/lib/vauth/digest_sspi.c
@@ -0,0 +1,527 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 2014 - 2015, Steve Holme, <steve_holme@hotmail.com>.
+ * Copyright (C) 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * RFC2831 DIGEST-MD5 authentication
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#if defined(USE_WINDOWS_SSPI) && !defined(CURL_DISABLE_CRYPTO_AUTH)
+
+#include <curl/curl.h>
+
+#include "vauth/vauth.h"
+#include "vauth/digest.h"
+#include "urldata.h"
+#include "curl_base64.h"
+#include "warnless.h"
+#include "curl_multibyte.h"
+#include "sendf.h"
+#include "strdup.h"
+#include "rawstr.h"
+
+/* The last #include files should be: */
+#include "curl_memory.h"
+#include "memdebug.h"
+
+/*
+ * Curl_sasl_create_digest_md5_message()
+ *
+ * This is used to generate an already encoded DIGEST-MD5 response message
+ * ready for sending to the recipient.
+ *
+ * Parameters:
+ *
+ * data    [in]     - The session handle.
+ * chlg64  [in]     - The base64 encoded challenge message.
+ * userp   [in]     - The user name in the format User or Domain\User.
+ * passdwp [in]     - The user's password.
+ * service [in]     - The service type such as www, smtp, pop or imap.
+ * outptr  [in/out] - The address where a pointer to newly allocated memory
+ *                    holding the result will be stored upon completion.
+ * outlen  [out]    - The length of the output message.
+ *
+ * Returns CURLE_OK on success.
+ */
+CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
+                                             const char *chlg64,
+                                             const char *userp,
+                                             const char *passwdp,
+                                             const char *service,
+                                             char **outptr, size_t *outlen)
+{
+  CURLcode result = CURLE_OK;
+  TCHAR *spn = NULL;
+  size_t chlglen = 0;
+  size_t token_max = 0;
+  unsigned char *input_token = NULL;
+  unsigned char *output_token = NULL;
+  CredHandle credentials;
+  CtxtHandle context;
+  PSecPkgInfo SecurityPackage;
+  SEC_WINNT_AUTH_IDENTITY identity;
+  SEC_WINNT_AUTH_IDENTITY *p_identity;
+  SecBuffer chlg_buf;
+  SecBuffer resp_buf;
+  SecBufferDesc chlg_desc;
+  SecBufferDesc resp_desc;
+  SECURITY_STATUS status;
+  unsigned long attrs;
+  TimeStamp expiry; /* For Windows 9x compatibility of SSPI calls */
+
+  /* Decode the base-64 encoded challenge message */
+  if(strlen(chlg64) && *chlg64 != '=') {
+    result = Curl_base64_decode(chlg64, &input_token, &chlglen);
+    if(result)
+      return result;
+  }
+
+  /* Ensure we have a valid challenge message */
+  if(!input_token) {
+    infof(data, "DIGEST-MD5 handshake failure (empty challenge message)\n");
+
+    return CURLE_BAD_CONTENT_ENCODING;
+  }
+
+  /* Query the security package for DigestSSP */
+  status = s_pSecFn->QuerySecurityPackageInfo((TCHAR *) TEXT(SP_NAME_DIGEST),
+                                              &SecurityPackage);
+  if(status != SEC_E_OK) {
+    free(input_token);
+
+    return CURLE_NOT_BUILT_IN;
+  }
+
+  token_max = SecurityPackage->cbMaxToken;
+
+  /* Release the package buffer as it is not required anymore */
+  s_pSecFn->FreeContextBuffer(SecurityPackage);
+
+  /* Allocate our response buffer */
+  output_token = malloc(token_max);
+  if(!output_token) {
+    free(input_token);
+
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  /* Generate our SPN */
+  spn = Curl_sasl_build_spn(service, data->easy_conn->host.name);
+  if(!spn) {
+    free(output_token);
+    free(input_token);
+
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  if(userp && *userp) {
+    /* Populate our identity structure */
+    result = Curl_create_sspi_identity(userp, passwdp, &identity);
+    if(result) {
+      free(spn);
+      free(output_token);
+      free(input_token);
+
+      return result;
+    }
+
+    /* Allow proper cleanup of the identity structure */
+    p_identity = &identity;
+  }
+  else
+    /* Use the current Windows user */
+    p_identity = NULL;
+
+  /* Acquire our credentials handle */
+  status = s_pSecFn->AcquireCredentialsHandle(NULL,
+                                              (TCHAR *) TEXT(SP_NAME_DIGEST),
+                                              SECPKG_CRED_OUTBOUND, NULL,
+                                              p_identity, NULL, NULL,
+                                              &credentials, &expiry);
+
+  if(status != SEC_E_OK) {
+    Curl_sspi_free_identity(p_identity);
+    free(spn);
+    free(output_token);
+    free(input_token);
+
+    return CURLE_LOGIN_DENIED;
+  }
+
+  /* Setup the challenge "input" security buffer */
+  chlg_desc.ulVersion = SECBUFFER_VERSION;
+  chlg_desc.cBuffers  = 1;
+  chlg_desc.pBuffers  = &chlg_buf;
+  chlg_buf.BufferType = SECBUFFER_TOKEN;
+  chlg_buf.pvBuffer   = input_token;
+  chlg_buf.cbBuffer   = curlx_uztoul(chlglen);
+
+  /* Setup the response "output" security buffer */
+  resp_desc.ulVersion = SECBUFFER_VERSION;
+  resp_desc.cBuffers  = 1;
+  resp_desc.pBuffers  = &resp_buf;
+  resp_buf.BufferType = SECBUFFER_TOKEN;
+  resp_buf.pvBuffer   = output_token;
+  resp_buf.cbBuffer   = curlx_uztoul(token_max);
+
+  /* Generate our response message */
+  status = s_pSecFn->InitializeSecurityContext(&credentials, NULL, spn,
+                                               0, 0, 0, &chlg_desc, 0,
+                                               &context, &resp_desc, &attrs,
+                                               &expiry);
+
+  if(status == SEC_I_COMPLETE_NEEDED ||
+     status == SEC_I_COMPLETE_AND_CONTINUE)
+    s_pSecFn->CompleteAuthToken(&credentials, &resp_desc);
+  else if(status != SEC_E_OK && status != SEC_I_CONTINUE_NEEDED) {
+    s_pSecFn->FreeCredentialsHandle(&credentials);
+    Curl_sspi_free_identity(p_identity);
+    free(spn);
+    free(output_token);
+    free(input_token);
+
+    return CURLE_RECV_ERROR;
+  }
+
+  /* Base64 encode the response */
+  result = Curl_base64_encode(data, (char *) output_token, resp_buf.cbBuffer,
+                              outptr, outlen);
+
+  /* Free our handles */
+  s_pSecFn->DeleteSecurityContext(&context);
+  s_pSecFn->FreeCredentialsHandle(&credentials);
+
+  /* Free the identity structure */
+  Curl_sspi_free_identity(p_identity);
+
+  /* Free the SPN */
+  free(spn);
+
+  /* Free the response buffer */
+  free(output_token);
+
+  /* Free the decoded challenge message */
+  free(input_token);
+
+  return result;
+}
+
+/*
+ * Curl_override_sspi_http_realm()
+ *
+ * This is used to populate the domain in a SSPI identity structure
+ * The realm is extracted from the challenge message and used as the
+ * domain if it is not already explicitly set.
+ *
+ * Parameters:
+ *
+ * chlg     [in]     - The challenge message.
+ * identity [in/out] - The identity structure.
+ *
+ * Returns CURLE_OK on success.
+ */
+CURLcode Curl_override_sspi_http_realm(const char *chlg,
+                                       SEC_WINNT_AUTH_IDENTITY *identity)
+{
+  xcharp_u domain, dup_domain;
+
+  /* If domain is blank or unset, check challenge message for realm */
+  if(!identity->Domain || !identity->DomainLength) {
+    for(;;) {
+      char value[DIGEST_MAX_VALUE_LENGTH];
+      char content[DIGEST_MAX_CONTENT_LENGTH];
+
+      /* Pass all additional spaces here */
+      while(*chlg && ISSPACE(*chlg))
+        chlg++;
+
+      /* Extract a value=content pair */
+      if(Curl_sasl_digest_get_pair(chlg, value, content, &chlg)) {
+        if(Curl_raw_equal(value, "realm")) {
+
+          /* Setup identity's domain and length */
+          domain.tchar_ptr = Curl_convert_UTF8_to_tchar((char *) content);
+          if(!domain.tchar_ptr)
+            return CURLE_OUT_OF_MEMORY;
+
+          dup_domain.tchar_ptr = _tcsdup(domain.tchar_ptr);
+          if(!dup_domain.tchar_ptr) {
+            Curl_unicodefree(domain.tchar_ptr);
+            return CURLE_OUT_OF_MEMORY;
+          }
+
+          free(identity->Domain);
+          identity->Domain = dup_domain.tbyte_ptr;
+          identity->DomainLength = curlx_uztoul(_tcslen(dup_domain.tchar_ptr));
+          dup_domain.tchar_ptr = NULL;
+
+          Curl_unicodefree(domain.tchar_ptr);
+        }
+        else {
+          /* Unknown specifier, ignore it! */
+        }
+      }
+      else
+        break; /* We're done here */
+
+      /* Pass all additional spaces here */
+      while(*chlg && ISSPACE(*chlg))
+        chlg++;
+
+      /* Allow the list to be comma-separated */
+      if(',' == *chlg)
+        chlg++;
+    }
+  }
+
+  return CURLE_OK;
+}
+
+/*
+ * Curl_sasl_decode_digest_http_message()
+ *
+ * This is used to decode a HTTP DIGEST challenge message into the seperate
+ * attributes.
+ *
+ * Parameters:
+ *
+ * chlg    [in]     - The challenge message.
+ * digest  [in/out] - The digest data struct being used and modified.
+ *
+ * Returns CURLE_OK on success.
+ */
+CURLcode Curl_sasl_decode_digest_http_message(const char *chlg,
+                                              struct digestdata *digest)
+{
+  size_t chlglen = strlen(chlg);
+
+  /* We had an input token before and we got another one now. This means we
+     provided bad credentials in the previous request. */
+  if(digest->input_token)
+    return CURLE_BAD_CONTENT_ENCODING;
+
+  /* Simply store the challenge for use later */
+  digest->input_token = (BYTE *) Curl_memdup(chlg, chlglen);
+  if(!digest->input_token)
+    return CURLE_OUT_OF_MEMORY;
+
+  digest->input_token_len = chlglen;
+
+  return CURLE_OK;
+}
+
+/*
+ * Curl_sasl_create_digest_http_message()
+ *
+ * This is used to generate a HTTP DIGEST response message ready for sending
+ * to the recipient.
+ *
+ * Parameters:
+ *
+ * data    [in]     - The session handle.
+ * userp   [in]     - The user name in the format User or Domain\User.
+ * passdwp [in]     - The user's password.
+ * request [in]     - The HTTP request.
+ * uripath [in]     - The path of the HTTP uri.
+ * digest  [in/out] - The digest data struct being used and modified.
+ * outptr  [in/out] - The address where a pointer to newly allocated memory
+ *                    holding the result will be stored upon completion.
+ * outlen  [out]    - The length of the output message.
+ *
+ * Returns CURLE_OK on success.
+ */
+CURLcode Curl_sasl_create_digest_http_message(struct SessionHandle *data,
+                                              const char *userp,
+                                              const char *passwdp,
+                                              const unsigned char *request,
+                                              const unsigned char *uripath,
+                                              struct digestdata *digest,
+                                              char **outptr, size_t *outlen)
+{
+  size_t token_max;
+  CredHandle credentials;
+  CtxtHandle context;
+  char *resp;
+  BYTE *output_token;
+  PSecPkgInfo SecurityPackage;
+  SEC_WINNT_AUTH_IDENTITY identity;
+  SEC_WINNT_AUTH_IDENTITY *p_identity;
+  SecBuffer chlg_buf[3];
+  SecBuffer resp_buf;
+  SecBufferDesc chlg_desc;
+  SecBufferDesc resp_desc;
+  SECURITY_STATUS status;
+  unsigned long attrs;
+  TimeStamp expiry; /* For Windows 9x compatibility of SSPI calls */
+  TCHAR *spn;
+
+  (void) data;
+
+  /* Query the security package for DigestSSP */
+  status = s_pSecFn->QuerySecurityPackageInfo((TCHAR *) TEXT(SP_NAME_DIGEST),
+                                              &SecurityPackage);
+  if(status != SEC_E_OK)
+    return CURLE_NOT_BUILT_IN;
+
+  token_max = SecurityPackage->cbMaxToken;
+
+  /* Release the package buffer as it is not required anymore */
+  s_pSecFn->FreeContextBuffer(SecurityPackage);
+
+  /* Allocate the output buffer according to the max token size as indicated
+     by the security package */
+  output_token = malloc(token_max);
+  if(!output_token)
+    return CURLE_OUT_OF_MEMORY;
+
+  if(userp && *userp) {
+    /* Populate our identity structure */
+    if(Curl_create_sspi_identity(userp, passwdp, &identity))
+      return CURLE_OUT_OF_MEMORY;
+
+    /* Populate our identity domain */
+    if(Curl_override_sspi_http_realm((const char*) digest->input_token,
+                                     &identity))
+      return CURLE_OUT_OF_MEMORY;
+
+    /* Allow proper cleanup of the identity structure */
+    p_identity = &identity;
+  }
+  else
+    /* Use the current Windows user */
+    p_identity = NULL;
+
+  /* Acquire our credentials handle */
+  status = s_pSecFn->AcquireCredentialsHandle(NULL,
+                                              (TCHAR *) TEXT(SP_NAME_DIGEST),
+                                              SECPKG_CRED_OUTBOUND, NULL,
+                                              p_identity, NULL, NULL,
+                                              &credentials, &expiry);
+  if(status != SEC_E_OK) {
+    Curl_sspi_free_identity(p_identity);
+    free(output_token);
+
+    return CURLE_LOGIN_DENIED;
+  }
+
+  /* Setup the challenge "input" security buffer if present */
+  chlg_desc.ulVersion    = SECBUFFER_VERSION;
+  chlg_desc.cBuffers     = 3;
+  chlg_desc.pBuffers     = chlg_buf;
+  chlg_buf[0].BufferType = SECBUFFER_TOKEN;
+  chlg_buf[0].pvBuffer   = digest->input_token;
+  chlg_buf[0].cbBuffer   = curlx_uztoul(digest->input_token_len);
+  chlg_buf[1].BufferType = SECBUFFER_PKG_PARAMS;
+  chlg_buf[1].pvBuffer   = (void *) request;
+  chlg_buf[1].cbBuffer   = curlx_uztoul(strlen((const char *) request));
+  chlg_buf[2].BufferType = SECBUFFER_PKG_PARAMS;
+  chlg_buf[2].pvBuffer   = NULL;
+  chlg_buf[2].cbBuffer   = 0;
+
+  /* Setup the response "output" security buffer */
+  resp_desc.ulVersion = SECBUFFER_VERSION;
+  resp_desc.cBuffers  = 1;
+  resp_desc.pBuffers  = &resp_buf;
+  resp_buf.BufferType = SECBUFFER_TOKEN;
+  resp_buf.pvBuffer   = output_token;
+  resp_buf.cbBuffer   = curlx_uztoul(token_max);
+
+  spn = Curl_convert_UTF8_to_tchar((char *) uripath);
+  if(!spn) {
+    Curl_sspi_free_identity(p_identity);
+    free(output_token);
+
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  /* Generate our reponse message */
+  status = s_pSecFn->InitializeSecurityContext(&credentials, NULL,
+                                               spn,
+                                               ISC_REQ_USE_HTTP_STYLE, 0, 0,
+                                               &chlg_desc, 0, &context,
+                                               &resp_desc, &attrs, &expiry);
+  Curl_unicodefree(spn);
+
+  if(status == SEC_I_COMPLETE_NEEDED ||
+     status == SEC_I_COMPLETE_AND_CONTINUE)
+    s_pSecFn->CompleteAuthToken(&credentials, &resp_desc);
+  else if(status != SEC_E_OK && status != SEC_I_CONTINUE_NEEDED) {
+    s_pSecFn->FreeCredentialsHandle(&credentials);
+
+    Curl_sspi_free_identity(p_identity);
+    free(output_token);
+
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  resp = malloc(resp_buf.cbBuffer + 1);
+  if(!resp) {
+    s_pSecFn->DeleteSecurityContext(&context);
+    s_pSecFn->FreeCredentialsHandle(&credentials);
+
+    Curl_sspi_free_identity(p_identity);
+    free(output_token);
+
+    return CURLE_OUT_OF_MEMORY;
+  }
+
+  /* Copy the generated reponse */
+  memcpy(resp, resp_buf.pvBuffer, resp_buf.cbBuffer);
+  resp[resp_buf.cbBuffer] = 0x00;
+
+  /* Return the response */
+  *outptr = resp;
+  *outlen = resp_buf.cbBuffer;
+
+  /* Free our handles */
+  s_pSecFn->DeleteSecurityContext(&context);
+  s_pSecFn->FreeCredentialsHandle(&credentials);
+
+  /* Free the identity structure */
+  Curl_sspi_free_identity(p_identity);
+
+  /* Free the response buffer */
+  free(output_token);
+
+  return CURLE_OK;
+}
+
+/*
+ * Curl_sasl_digest_cleanup()
+ *
+ * This is used to clean up the digest specific data.
+ *
+ * Parameters:
+ *
+ * digest    [in/out] - The digest data struct being cleaned up.
+ *
+ */
+void Curl_sasl_digest_cleanup(struct digestdata *digest)
+{
+  /* Free the input token */
+  Curl_safefree(digest->input_token);
+
+  /* Reset any variables */
+  digest->input_token_len = 0;
+}
+
+#endif /* USE_WINDOWS_SSPI && !CURL_DISABLE_CRYPTO_AUTH */
diff --git a/lib/vauth/vauth.h b/lib/vauth/vauth.h
index 7469ccd8b..71afc40b9 100644
--- a/lib/vauth/vauth.h
+++ b/lib/vauth/vauth.h
@@ -26,6 +26,10 @@
 
 struct SessionHandle;
 
+#if !defined(CURL_DISABLE_CRYPTO_AUTH)
+struct digestdata;
+#endif
+
 /* This is used to build a SPN string */
 #if !defined(USE_WINDOWS_SSPI)
 char *Curl_sasl_build_spn(const char *service, const char *instance);
@@ -64,6 +68,30 @@ CURLcode sasl_create_cram_md5_message(struct SessionHandle *data,
                                       const char *userp,
                                       const char *passwdp,
                                       char **outptr, size_t *outlen);
+
+/* This is used to generate a base64 encoded DIGEST-MD5 response message */
+CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data,
+                                             const char *chlg64,
+                                             const char *userp,
+                                             const char *passwdp,
+                                             const char *service,
+                                             char **outptr, size_t *outlen);
+
+/* This is used to decode a HTTP DIGEST challenge message */
+CURLcode Curl_sasl_decode_digest_http_message(const char *chlg,
+                                              struct digestdata *digest);
+
+/* This is used to generate a HTTP DIGEST response message */
+CURLcode Curl_sasl_create_digest_http_message(struct SessionHandle *data,
+                                              const char *userp,
+                                              const char *passwdp,
+                                              const unsigned char *request,
+                                              const unsigned char *uri,
+                                              struct digestdata *digest,
+                                              char **outptr, size_t *outlen);
+
+/* This is used to clean up the digest specific data */
+void Curl_sasl_digest_cleanup(struct digestdata *digest);
 #endif /* !CURL_DISABLE_CRYPTO_AUTH */
 
 #endif /* HEADER_CURL_VAUTH_H */