2 * Copyright notice from original mutt:
3 * Copyright (C) 1999-2000 Brendan Cully <brendan@kublai.com>
5 * This file is part of mutt-ng, see http://www.muttng.org/.
6 * It's licensed under the GNU General Public License,
7 * please see the file GPL in the top level source directory.
10 /* IMAP login/authentication code */
12 #include <lib-lib/lib-lib.h>
15 #include "imap_private.h"
18 #define MD5_BLOCK_LEN 64
19 #define MD5_DIGEST_LEN 16
21 #include <lib-hash/hash.h>
23 /* forward declarations */
24 static void hmac_md5 (const char *password, char *challenge,
25 unsigned char *response);
27 /* imap_auth_cram_md5: AUTH=CRAM-MD5 support. */
28 imap_auth_res_t imap_auth_cram_md5 (IMAP_DATA * idata, const char *method __attribute__ ((unused)))
30 char ibuf[LONG_STRING * 2], obuf[LONG_STRING];
31 unsigned char hmac_response[MD5_DIGEST_LEN];
35 if (!mutt_bit_isset (idata->capabilities, ACRAM_MD5))
36 return IMAP_AUTH_UNAVAIL;
38 mutt_message _("Authenticating (CRAM-MD5)...");
41 if (mutt_account_getlogin (&idata->conn->account))
42 return IMAP_AUTH_FAILURE;
43 if (mutt_account_getpass (&idata->conn->account))
44 return IMAP_AUTH_FAILURE;
46 imap_cmd_start (idata, "AUTHENTICATE CRAM-MD5");
49 * The data encoded in the first ready response contains a presumptively
50 * arbitrary string of random digits, a timestamp, and the fully-qualified
51 * primary host name of the server. The syntax of the unencoded form must
52 * correspond to that of an RFC 822 'msg-id' [RFC822] as described in [POP3].
55 rc = imap_cmd_step (idata);
56 while (rc == IMAP_CMD_CONTINUE);
58 if (rc != IMAP_CMD_RESPOND) {
62 if ((len = mutt_from_base64 (obuf, idata->cmd.buf + 2)) == -1) {
68 /* The client makes note of the data and then responds with a string
69 * consisting of the user name, a space, and a 'digest'. The latter is
70 * computed by applying the keyed MD5 algorithm from [KEYED-MD5] where the
71 * key is a shared secret and the digested text is the timestamp (including
74 * Note: The user name shouldn't be quoted. Since the digest can't contain
75 * spaces, there is no ambiguity. Some servers get this wrong, we'll work
76 * around them when the bug report comes in. Until then, we'll remain
77 * blissfully RFC-compliant.
79 hmac_md5 (idata->conn->account.pass, obuf, hmac_response);
80 /* dubious optimisation I saw elsewhere: make the whole string in one call */
81 snprintf (obuf, sizeof (obuf),
82 "%s %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
83 idata->conn->account.user,
84 hmac_response[0], hmac_response[1], hmac_response[2],
85 hmac_response[3], hmac_response[4], hmac_response[5],
86 hmac_response[6], hmac_response[7], hmac_response[8],
87 hmac_response[9], hmac_response[10], hmac_response[11],
88 hmac_response[12], hmac_response[13], hmac_response[14],
91 /* XXX - ibuf must be long enough to store the base64 encoding of obuf,
92 * plus the additional debris
95 mutt_to_base64 ((unsigned char *) ibuf, (unsigned char *) obuf,
96 m_strlen(obuf), sizeof (ibuf) - 2);
97 m_strcat(ibuf, sizeof(ibuf), "\r\n");
98 mutt_socket_write (idata->conn, ibuf);
101 rc = imap_cmd_step (idata);
102 while (rc == IMAP_CMD_CONTINUE);
104 if (rc != IMAP_CMD_OK) {
108 if (imap_code (idata->cmd.buf))
109 return IMAP_AUTH_SUCCESS;
112 mutt_error _("CRAM-MD5 authentication failed.");
114 return IMAP_AUTH_FAILURE;
117 /* hmac_md5: produce CRAM-MD5 challenge response. */
118 static void hmac_md5 (const char *password, char *challenge,
119 unsigned char *response)
122 unsigned char ipad[MD5_BLOCK_LEN], opad[MD5_BLOCK_LEN];
123 unsigned char secret[MD5_BLOCK_LEN + 1];
124 unsigned char hash_passwd[MD5_DIGEST_LEN];
125 unsigned int secret_len, chal_len;
128 secret_len = m_strlen(password);
129 chal_len = m_strlen(challenge);
131 /* passwords longer than MD5_BLOCK_LEN bytes are substituted with their MD5
133 if (secret_len > MD5_BLOCK_LEN) {
135 MD5Update (&ctx, (unsigned char *) password, secret_len);
136 MD5Final (hash_passwd, &ctx);
137 m_strcpy((char *)secret, MD5_DIGEST_LEN, (char *)hash_passwd);
138 secret_len = MD5_DIGEST_LEN;
141 m_strcpy((char *)secret, sizeof(secret), password);
145 memcpy (ipad, secret, secret_len);
146 memcpy (opad, secret, secret_len);
148 for (i = 0; i < MD5_BLOCK_LEN; i++) {
153 /* inner hash: challenge and ipadded secret */
155 MD5Update (&ctx, ipad, MD5_BLOCK_LEN);
156 MD5Update (&ctx, (unsigned char *) challenge, chal_len);
157 MD5Final (response, &ctx);
159 /* outer hash: inner hash and opadded secret */
161 MD5Update (&ctx, opad, MD5_BLOCK_LEN);
162 MD5Update (&ctx, response, MD5_DIGEST_LEN);
163 MD5Final (response, &ctx);