2 * Copyright (C) 1999-2000 Brendan Cully <brendan@kublai.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
19 /* IMAP login/authentication code */
26 #include "imap_private.h"
30 #define MD5_BLOCK_LEN 64
31 #define MD5_DIGEST_LEN 16
33 /* forward declarations */
34 static void hmac_md5 (const char *password, char *challenge,
35 unsigned char *response);
37 /* imap_auth_cram_md5: AUTH=CRAM-MD5 support. */
38 imap_auth_res_t imap_auth_cram_md5 (IMAP_DATA * idata, const char *method)
40 char ibuf[LONG_STRING * 2], obuf[LONG_STRING];
41 unsigned char hmac_response[MD5_DIGEST_LEN];
45 if (!mutt_bit_isset (idata->capabilities, ACRAM_MD5))
46 return IMAP_AUTH_UNAVAIL;
48 mutt_message _("Authenticating (CRAM-MD5)...");
51 if (mutt_account_getuser (&idata->conn->account))
52 return IMAP_AUTH_FAILURE;
53 if (mutt_account_getpass (&idata->conn->account))
54 return IMAP_AUTH_FAILURE;
56 imap_cmd_start (idata, "AUTHENTICATE CRAM-MD5");
59 * The data encoded in the first ready response contains a presumptively
60 * arbitrary string of random digits, a timestamp, and the fully-qualified
61 * primary host name of the server. The syntax of the unencoded form must
62 * correspond to that of an RFC 822 'msg-id' [RFC822] as described in [POP3].
65 rc = imap_cmd_step (idata);
66 while (rc == IMAP_CMD_CONTINUE);
68 if (rc != IMAP_CMD_RESPOND) {
69 dprint (1, (debugfile, "Invalid response from server: %s\n", ibuf));
73 if ((len = mutt_from_base64 (obuf, idata->cmd.buf + 2)) == -1) {
74 dprint (1, (debugfile, "Error decoding base64 response.\n"));
79 dprint (2, (debugfile, "CRAM challenge: %s\n", obuf));
81 /* The client makes note of the data and then responds with a string
82 * consisting of the user name, a space, and a 'digest'. The latter is
83 * computed by applying the keyed MD5 algorithm from [KEYED-MD5] where the
84 * key is a shared secret and the digested text is the timestamp (including
87 * Note: The user name shouldn't be quoted. Since the digest can't contain
88 * spaces, there is no ambiguity. Some servers get this wrong, we'll work
89 * around them when the bug report comes in. Until then, we'll remain
90 * blissfully RFC-compliant.
92 hmac_md5 (idata->conn->account.pass, obuf, hmac_response);
93 /* dubious optimisation I saw elsewhere: make the whole string in one call */
94 snprintf (obuf, sizeof (obuf),
95 "%s %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
96 idata->conn->account.user,
97 hmac_response[0], hmac_response[1], hmac_response[2],
98 hmac_response[3], hmac_response[4], hmac_response[5],
99 hmac_response[6], hmac_response[7], hmac_response[8],
100 hmac_response[9], hmac_response[10], hmac_response[11],
101 hmac_response[12], hmac_response[13], hmac_response[14],
103 dprint (2, (debugfile, "CRAM response: %s\n", obuf));
105 /* XXX - ibuf must be long enough to store the base64 encoding of obuf,
106 * plus the additional debris
109 mutt_to_base64 ((unsigned char *) ibuf, (unsigned char *) obuf,
110 strlen (obuf), sizeof (ibuf) - 2);
111 safe_strcat (ibuf, sizeof (ibuf), "\r\n");
112 mutt_socket_write (idata->conn, ibuf);
115 rc = imap_cmd_step (idata);
116 while (rc == IMAP_CMD_CONTINUE);
118 if (rc != IMAP_CMD_OK) {
119 dprint (1, (debugfile, "Error receiving server response.\n"));
123 if (imap_code (idata->cmd.buf))
124 return IMAP_AUTH_SUCCESS;
127 mutt_error _("CRAM-MD5 authentication failed.");
129 return IMAP_AUTH_FAILURE;
132 /* hmac_md5: produce CRAM-MD5 challenge response. */
133 static void hmac_md5 (const char *password, char *challenge,
134 unsigned char *response)
137 unsigned char ipad[MD5_BLOCK_LEN], opad[MD5_BLOCK_LEN];
138 unsigned char secret[MD5_BLOCK_LEN + 1];
139 unsigned char hash_passwd[MD5_DIGEST_LEN];
140 unsigned int secret_len, chal_len;
143 secret_len = strlen (password);
144 chal_len = strlen (challenge);
146 /* passwords longer than MD5_BLOCK_LEN bytes are substituted with their MD5
148 if (secret_len > MD5_BLOCK_LEN) {
150 MD5Update (&ctx, (unsigned char *) password, secret_len);
151 MD5Final (hash_passwd, &ctx);
152 strfcpy ((char *) secret, (char *) hash_passwd, MD5_DIGEST_LEN);
153 secret_len = MD5_DIGEST_LEN;
156 strfcpy ((char *) secret, password, sizeof (secret));
158 memset (ipad, 0, sizeof (ipad));
159 memset (opad, 0, sizeof (opad));
160 memcpy (ipad, secret, secret_len);
161 memcpy (opad, secret, secret_len);
163 for (i = 0; i < MD5_BLOCK_LEN; i++) {
168 /* inner hash: challenge and ipadded secret */
170 MD5Update (&ctx, ipad, MD5_BLOCK_LEN);
171 MD5Update (&ctx, (unsigned char *) challenge, chal_len);
172 MD5Final (response, &ctx);
174 /* outer hash: inner hash and opadded secret */
176 MD5Update (&ctx, opad, MD5_BLOCK_LEN);
177 MD5Update (&ctx, response, MD5_DIGEST_LEN);
178 MD5Final (response, &ctx);