diff --git a/lib/strerror.c b/lib/strerror.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 2004 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 2004 - 2012, 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
@@ -781,3 +781,315 @@ const char *Curl_idn_strerror (struct connectdata *conn, int err)
 #endif
 }
 #endif  /* USE_LIBIDN */
+
+#ifdef USE_WINDOWS_SSPI
+const char *Curl_sspi_strerror (struct connectdata *conn, int err)
+{
+#ifndef CURL_DISABLE_VERBOSE_STRINGS
+  char txtbuf[sizeof("Unknown error (0xffffffff)")];
+  char msgbuf[sizeof(conn->syserr_buf)];
+  int old_errno;
+  char *msg = NULL;
+#endif
+  const char *txt;
+  char *outbuf;
+  size_t outmax;
+
+  DEBUGASSERT(conn);
+
+  outbuf = conn->syserr_buf;
+  outmax = sizeof(conn->syserr_buf)-1;
+  *outbuf = '\0';
+
+#ifndef CURL_DISABLE_VERBOSE_STRINGS
+
+  old_errno = ERRNO;
+
+  switch (err) {
+    case SEC_E_OK:
+      txt = "No error";
+      break;
+    case SEC_E_ALGORITHM_MISMATCH:
+      txt = "SEC_E_ALGORITHM_MISMATCH";
+      break;
+    case SEC_E_BAD_BINDINGS:
+      txt = "SEC_E_BAD_BINDINGS";
+      break;
+    case SEC_E_BAD_PKGID:
+      txt = "SEC_E_BAD_PKGID";
+      break;
+    case SEC_E_BUFFER_TOO_SMALL:
+      txt = "SEC_E_BUFFER_TOO_SMALL";
+      break;
+    case SEC_E_CANNOT_INSTALL:
+      txt = "SEC_E_CANNOT_INSTALL";
+      break;
+    case SEC_E_CANNOT_PACK:
+      txt = "SEC_E_CANNOT_PACK";
+      break;
+    case SEC_E_CERT_EXPIRED:
+      txt = "SEC_E_CERT_EXPIRED";
+      break;
+    case SEC_E_CERT_UNKNOWN:
+      txt = "SEC_E_CERT_UNKNOWN";
+      break;
+    case SEC_E_CERT_WRONG_USAGE:
+      txt = "SEC_E_CERT_WRONG_USAGE";
+      break;
+    case SEC_E_CONTEXT_EXPIRED:
+      txt = "SEC_E_CONTEXT_EXPIRED";
+      break;
+    case SEC_E_CROSSREALM_DELEGATION_FAILURE:
+      txt = "SEC_E_CROSSREALM_DELEGATION_FAILURE";
+      break;
+    case SEC_E_CRYPTO_SYSTEM_INVALID:
+      txt = "SEC_E_CRYPTO_SYSTEM_INVALID";
+      break;
+    case SEC_E_DECRYPT_FAILURE:
+      txt = "SEC_E_DECRYPT_FAILURE";
+      break;
+    case SEC_E_DELEGATION_POLICY:
+      txt = "SEC_E_DELEGATION_POLICY";
+      break;
+    case SEC_E_DELEGATION_REQUIRED:
+      txt = "SEC_E_DELEGATION_REQUIRED";
+      break;
+    case SEC_E_DOWNGRADE_DETECTED:
+      txt = "SEC_E_DOWNGRADE_DETECTED";
+      break;
+    case SEC_E_ENCRYPT_FAILURE:
+      txt = "SEC_E_ENCRYPT_FAILURE";
+      break;
+    case SEC_E_ILLEGAL_MESSAGE:
+      txt = "SEC_E_ILLEGAL_MESSAGE";
+      break;
+    case SEC_E_INCOMPLETE_CREDENTIALS:
+      txt = "SEC_E_INCOMPLETE_CREDENTIALS";
+      break;
+    case SEC_E_INCOMPLETE_MESSAGE:
+      txt = "SEC_E_INCOMPLETE_MESSAGE";
+      break;
+    case SEC_E_INSUFFICIENT_MEMORY:
+      txt = "SEC_E_INSUFFICIENT_MEMORY";
+      break;
+    case SEC_E_INTERNAL_ERROR:
+      txt = "SEC_E_INTERNAL_ERROR";
+      break;
+    case SEC_E_INVALID_HANDLE:
+      txt = "SEC_E_INVALID_HANDLE";
+      break;
+    case SEC_E_INVALID_PARAMETER:
+      txt = "SEC_E_INVALID_PARAMETER";
+      break;
+    case SEC_E_INVALID_TOKEN:
+      txt = "SEC_E_INVALID_TOKEN";
+      break;
+    case SEC_E_ISSUING_CA_UNTRUSTED:
+      txt = "SEC_E_ISSUING_CA_UNTRUSTED";
+      break;
+    case SEC_E_ISSUING_CA_UNTRUSTED_KDC:
+      txt = "SEC_E_ISSUING_CA_UNTRUSTED_KDC";
+      break;
+    case SEC_E_KDC_CERT_EXPIRED:
+      txt = "SEC_E_KDC_CERT_EXPIRED";
+      break;
+    case SEC_E_KDC_CERT_REVOKED:
+      txt = "SEC_E_KDC_CERT_REVOKED";
+      break;
+    case SEC_E_KDC_INVALID_REQUEST:
+      txt = "SEC_E_KDC_INVALID_REQUEST";
+      break;
+    case SEC_E_KDC_UNABLE_TO_REFER:
+      txt = "SEC_E_KDC_UNABLE_TO_REFER";
+      break;
+    case SEC_E_KDC_UNKNOWN_ETYPE:
+      txt = "SEC_E_KDC_UNKNOWN_ETYPE";
+      break;
+    case SEC_E_LOGON_DENIED:
+      txt = "SEC_E_LOGON_DENIED";
+      break;
+    case SEC_E_MAX_REFERRALS_EXCEEDED:
+      txt = "SEC_E_MAX_REFERRALS_EXCEEDED";
+      break;
+    case SEC_E_MESSAGE_ALTERED:
+      txt = "SEC_E_MESSAGE_ALTERED";
+      break;
+    case SEC_E_MULTIPLE_ACCOUNTS:
+      txt = "SEC_E_MULTIPLE_ACCOUNTS";
+      break;
+    case SEC_E_MUST_BE_KDC:
+      txt = "SEC_E_MUST_BE_KDC";
+      break;
+    case SEC_E_NOT_OWNER:
+      txt = "SEC_E_NOT_OWNER";
+      break;
+    case SEC_E_NO_AUTHENTICATING_AUTHORITY:
+      txt = "SEC_E_NO_AUTHENTICATING_AUTHORITY";
+      break;
+    case SEC_E_NO_CREDENTIALS:
+      txt = "SEC_E_NO_CREDENTIALS";
+      break;
+    case SEC_E_NO_IMPERSONATION:
+      txt = "SEC_E_NO_IMPERSONATION";
+      break;
+    case SEC_E_NO_IP_ADDRESSES:
+      txt = "SEC_E_NO_IP_ADDRESSES";
+      break;
+    case SEC_E_NO_KERB_KEY:
+      txt = "SEC_E_NO_KERB_KEY";
+      break;
+    case SEC_E_NO_PA_DATA:
+      txt = "SEC_E_NO_PA_DATA";
+      break;
+    case SEC_E_NO_S4U_PROT_SUPPORT:
+      txt = "SEC_E_NO_S4U_PROT_SUPPORT";
+      break;
+    case SEC_E_NO_TGT_REPLY:
+      txt = "SEC_E_NO_TGT_REPLY";
+      break;
+    case SEC_E_OUT_OF_SEQUENCE:
+      txt = "SEC_E_OUT_OF_SEQUENCE";
+      break;
+    case SEC_E_PKINIT_CLIENT_FAILURE:
+      txt = "SEC_E_PKINIT_CLIENT_FAILURE";
+      break;
+    case SEC_E_PKINIT_NAME_MISMATCH:
+      txt = "SEC_E_PKINIT_NAME_MISMATCH";
+      break;
+    case SEC_E_POLICY_NLTM_ONLY:
+      txt = "SEC_E_POLICY_NLTM_ONLY";
+      break;
+    case SEC_E_QOP_NOT_SUPPORTED:
+      txt = "SEC_E_QOP_NOT_SUPPORTED";
+      break;
+    case SEC_E_REVOCATION_OFFLINE_C:
+      txt = "SEC_E_REVOCATION_OFFLINE_C";
+      break;
+    case SEC_E_REVOCATION_OFFLINE_KDC:
+      txt = "SEC_E_REVOCATION_OFFLINE_KDC";
+      break;
+    case SEC_E_SECPKG_NOT_FOUND:
+      txt = "SEC_E_SECPKG_NOT_FOUND";
+      break;
+    case SEC_E_SECURITY_QOS_FAILED:
+      txt = "SEC_E_SECURITY_QOS_FAILED";
+      break;
+    case SEC_E_SHUTDOWN_IN_PROGRESS:
+      txt = "SEC_E_SHUTDOWN_IN_PROGRESS";
+      break;
+    case SEC_E_SMARTCARD_CERT_EXPIRED:
+      txt = "SEC_E_SMARTCARD_CERT_EXPIRED";
+      break;
+    case SEC_E_SMARTCARD_CERT_REVOKED:
+      txt = "SEC_E_SMARTCARD_CERT_REVOKED";
+      break;
+    case SEC_E_SMARTCARD_LOGON_REQUIRED:
+      txt = "SEC_E_SMARTCARD_LOGON_REQUIRED";
+      break;
+    case SEC_E_STRONG_CRYPTO_NOT_SUPPORTED:
+      txt = "SEC_E_STRONG_CRYPTO_NOT_SUPPORTED";
+      break;
+    case SEC_E_TARGET_UNKNOWN:
+      txt = "SEC_E_TARGET_UNKNOWN";
+      break;
+    case SEC_E_TIME_SKEW:
+      txt = "SEC_E_TIME_SKEW";
+      break;
+    case SEC_E_TOO_MANY_PRINCIPALS:
+      txt = "SEC_E_TOO_MANY_PRINCIPALS";
+      break;
+    case SEC_E_UNFINISHED_CONTEXT_DELETED:
+      txt = "SEC_E_UNFINISHED_CONTEXT_DELETED";
+      break;
+    case SEC_E_UNKNOWN_CREDENTIALS:
+      txt = "SEC_E_UNKNOWN_CREDENTIALS";
+      break;
+    case SEC_E_UNSUPPORTED_FUNCTION:
+      txt = "SEC_E_UNSUPPORTED_FUNCTION";
+      break;
+    case SEC_E_UNSUPPORTED_PREAUTH:
+      txt = "SEC_E_UNSUPPORTED_PREAUTH";
+      break;
+    case SEC_E_UNTRUSTED_ROOT:
+      txt = "SEC_E_UNTRUSTED_ROOT";
+      break;
+    case SEC_E_WRONG_CREDENTIAL_HANDLE:
+      txt = "SEC_E_WRONG_CREDENTIAL_HANDLE";
+      break;
+    case SEC_E_WRONG_PRINCIPAL:
+      txt = "SEC_E_WRONG_PRINCIPAL";
+      break;
+    case SEC_I_COMPLETE_AND_CONTINUE:
+      txt = "SEC_I_COMPLETE_AND_CONTINUE";
+      break;
+    case SEC_I_COMPLETE_NEEDED:
+      txt = "SEC_I_COMPLETE_NEEDED";
+      break;
+    case SEC_I_CONTEXT_EXPIRED:
+      txt = "SEC_I_CONTEXT_EXPIRED";
+      break;
+    case SEC_I_CONTINUE_NEEDED:
+      txt = "SEC_I_CONTINUE_NEEDED";
+      break;
+    case SEC_I_INCOMPLETE_CREDENTIALS:
+      txt = "SEC_I_INCOMPLETE_CREDENTIALS";
+      break;
+    case SEC_I_LOCAL_LOGON:
+      txt = "SEC_I_LOCAL_LOGON";
+      break;
+    case SEC_I_NO_LSA_CONTEXT:
+      txt = "SEC_I_NO_LSA_CONTEXT";
+      break;
+    case SEC_I_RENEGOTIATE:
+      txt = "SEC_I_RENEGOTIATE";
+      break;
+    case SEC_I_SIGNATURE_NEEDED:
+      txt = "SEC_I_SIGNATURE_NEEDED";
+      break;
+    default:
+      snprintf(txtbuf, sizeof(txtbuf), "Unknown error (0x%04X%04X)",
+               (err >> 16) & 0xffff, err & 0xffff);
+      txtbuf[sizeof(txtbuf)-1] = '\0';
+      txt = txtbuf;
+  }
+
+  if(err != SEC_E_OK) {
+    char *p;
+    if(FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM |
+                     FORMAT_MESSAGE_IGNORE_INSERTS,
+                     NULL, err, LANG_NEUTRAL,
+                     msgbuf, sizeof(msgbuf)-1, NULL)) {
+      msgbuf[sizeof(msgbuf)-1] = '\0';
+      /* strip trailing '\r\n' or '\n' */
+      if((p = strrchr(msgbuf,'\n')) != NULL && (p - msgbuf) >= 2)
+         *p = '\0';
+      if((p = strrchr(msgbuf,'\r')) != NULL && (p - msgbuf) >= 1)
+         *p = '\0';
+      msg = msgbuf;
+    }
+  }
+
+  if(msg)
+    snprintf(outbuf, outmax, "%s - %s", txt, msg);
+  else
+    strncpy(outbuf, txt, outmax);
+
+  if(old_errno != ERRNO)
+    SET_ERRNO(old_errno);
+
+#else
+
+  if(err == SEC_E_OK)
+    txt = "No error";
+  else
+    txt = "Error";
+
+  strncpy(outbuf, txt, outmax);
+
+#endif
+
+  outbuf[outmax] = '\0';
+
+  return outbuf;
+}
+#endif /* USE_WINDOWS_SSPI */
diff --git a/lib/strerror.h b/lib/strerror.h
@@ -1,13 +1,13 @@
-#ifndef __CURL_STRERROR_H
-#define __CURL_STRERROR_H
+#ifndef HEADER_CURL_STRERROR_H
+#define HEADER_CURL_STRERROR_H
 /***************************************************************************
  *                                  _   _ ____  _
  *  Project                     ___| | | |  _ \| |
  *                             / __| | | | |_) | |
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2009, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2012, 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
@@ -30,4 +30,8 @@ const char *Curl_strerror (struct connectdata *conn, int err);
 const char *Curl_idn_strerror (struct connectdata *conn, int err);
 #endif
 
+#ifdef USE_WINDOWS_SSPI
+const char *Curl_sspi_strerror (struct connectdata *conn, int err);
 #endif
+
+#endif /* HEADER_CURL_STRERROR_H */