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 */
22 #include "imap_private.h"
26 #define MD5_BLOCK_LEN 64
27 #define MD5_DIGEST_LEN 16
29 /* forward declarations */
30 static void hmac_md5 (const char* password, char* challenge,
31 unsigned char* response);
33 /* imap_auth_cram_md5: AUTH=CRAM-MD5 support. */
34 imap_auth_res_t imap_auth_cram_md5 (IMAP_DATA* idata, const char* method)
36 char ibuf[LONG_STRING*2], obuf[LONG_STRING];
37 unsigned char hmac_response[MD5_DIGEST_LEN];
41 if (!mutt_bit_isset (idata->capabilities, ACRAM_MD5))
42 return IMAP_AUTH_UNAVAIL;
44 mutt_message _("Authenticating (CRAM-MD5)...");
47 if (mutt_account_getuser (&idata->conn->account))
48 return IMAP_AUTH_FAILURE;
49 if (mutt_account_getpass (&idata->conn->account))
50 return IMAP_AUTH_FAILURE;
52 imap_cmd_start (idata, "AUTHENTICATE CRAM-MD5");
55 * The data encoded in the first ready response contains a presumptively
56 * arbitrary string of random digits, a timestamp, and the fully-qualified
57 * primary host name of the server. The syntax of the unencoded form must
58 * correspond to that of an RFC 822 'msg-id' [RFC822] as described in [POP3].
61 rc = imap_cmd_step (idata);
62 while (rc == IMAP_CMD_CONTINUE);
64 if (rc != IMAP_CMD_RESPOND)
66 dprint (1, (debugfile, "Invalid response from server: %s\n", ibuf));
70 if ((len = mutt_from_base64 (obuf, idata->cmd.buf + 2)) == -1)
72 dprint (1, (debugfile, "Error decoding base64 response.\n"));
77 dprint (2, (debugfile, "CRAM challenge: %s\n", obuf));
79 /* The client makes note of the data and then responds with a string
80 * consisting of the user name, a space, and a 'digest'. The latter is
81 * computed by applying the keyed MD5 algorithm from [KEYED-MD5] where the
82 * key is a shared secret and the digested text is the timestamp (including
85 * Note: The user name shouldn't be quoted. Since the digest can't contain
86 * spaces, there is no ambiguity. Some servers get this wrong, we'll work
87 * around them when the bug report comes in. Until then, we'll remain
88 * blissfully RFC-compliant.
90 hmac_md5 (idata->conn->account.pass, obuf, hmac_response);
91 /* dubious optimisation I saw elsewhere: make the whole string in one call */
92 snprintf (obuf, sizeof (obuf),
93 "%s %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
94 idata->conn->account.user,
95 hmac_response[0], hmac_response[1], hmac_response[2], hmac_response[3],
96 hmac_response[4], hmac_response[5], hmac_response[6], hmac_response[7],
97 hmac_response[8], hmac_response[9], hmac_response[10], hmac_response[11],
98 hmac_response[12], hmac_response[13], hmac_response[14], hmac_response[15]);
99 dprint(2, (debugfile, "CRAM response: %s\n", obuf));
101 /* XXX - ibuf must be long enough to store the base64 encoding of obuf,
102 * plus the additional debris
105 mutt_to_base64 ((unsigned char*) ibuf, (unsigned char*) obuf, strlen (obuf),
107 safe_strcat (ibuf, sizeof (ibuf), "\r\n");
108 mutt_socket_write (idata->conn, ibuf);
111 rc = imap_cmd_step (idata);
112 while (rc == IMAP_CMD_CONTINUE);
114 if (rc != IMAP_CMD_OK)
116 dprint (1, (debugfile, "Error receiving server response.\n"));
120 if (imap_code (idata->cmd.buf))
121 return IMAP_AUTH_SUCCESS;
124 mutt_error _("CRAM-MD5 authentication failed.");
126 return IMAP_AUTH_FAILURE;
129 /* hmac_md5: produce CRAM-MD5 challenge response. */
130 static void hmac_md5 (const char* password, char* challenge,
131 unsigned char* response)
134 unsigned char ipad[MD5_BLOCK_LEN], opad[MD5_BLOCK_LEN];
135 unsigned char secret[MD5_BLOCK_LEN+1];
136 unsigned char hash_passwd[MD5_DIGEST_LEN];
137 unsigned int secret_len, chal_len;
140 secret_len = strlen (password);
141 chal_len = strlen (challenge);
143 /* passwords longer than MD5_BLOCK_LEN bytes are substituted with their MD5
145 if (secret_len > MD5_BLOCK_LEN)
148 MD5Update (&ctx, (unsigned char*) password, secret_len);
149 MD5Final (hash_passwd, &ctx);
150 strfcpy ((char*) secret, (char*) hash_passwd, MD5_DIGEST_LEN);
151 secret_len = MD5_DIGEST_LEN;
154 strfcpy ((char *) secret, password, sizeof (secret));
156 memset (ipad, 0, sizeof (ipad));
157 memset (opad, 0, sizeof (opad));
158 memcpy (ipad, secret, secret_len);
159 memcpy (opad, secret, secret_len);
161 for (i = 0; i < MD5_BLOCK_LEN; i++)
167 /* inner hash: challenge and ipadded secret */
169 MD5Update (&ctx, ipad, MD5_BLOCK_LEN);
170 MD5Update (&ctx, (unsigned char*) challenge, chal_len);
171 MD5Final (response, &ctx);
173 /* outer hash: inner hash and opadded secret */
175 MD5Update (&ctx, opad, MD5_BLOCK_LEN);
176 MD5Update (&ctx, response, MD5_DIGEST_LEN);
177 MD5Final (response, &ctx);