/* * $Id: otp_mppe.c,v 1.1.2.3 2006/10/24 05:15:46 fcusack Exp $ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA * * Copyright 2001,2002 Google, Inc. * Copyright 2005,2006 TRI-D Systems, Inc. */ #include "ident.h" RCSID("$Id: otp_mppe.c,v 1.1.2.3 2006/10/24 05:15:46 fcusack Exp $") /* avoid inclusion of these FR headers which conflict w/ OpenSSL */ #define _LRAD_MD4_H #define _LRAD_SHA1_H #include #include "extern.h" #include "otp.h" #include "otp_mppe.h" #include #include #include #include #include /* * Add MPPE attributes to a request, if required. */ void otp_mppe(REQUEST *request, otp_pwe_t pwe, const otp_option_t *opt, const char *passcode) { VALUE_PAIR **avp = &request->reply->vps; VALUE_PAIR *cvp, *rvp, *vp; cvp = pairfind(request->packet->vps, pwattr[pwe - 1]); rvp = pairfind(request->packet->vps, pwattr[pwe]); switch (pwe) { case PWE_PAP: case PWE_CHAP: return; case PWE_MSCHAP: /* First, set some related attributes. */ vp = pairmake("MS-MPPE-Encryption-Policy", otp_mppe_policy[opt->mschap_mppe_policy], T_OP_EQ); rad_assert(vp != NULL); pairadd(avp, vp); vp = pairmake("MS-MPPE-Encryption-Types", otp_mppe_types[opt->mschap_mppe_types], T_OP_EQ); rad_assert(vp != NULL); pairadd(avp, vp); /* If no MPPE, we're done. */ if (!opt->mschap_mppe_policy) return; /* * Generate the MS-CHAP-MPPE-Keys attribute. This is not specified * anywhere -- RFC 2548, par. 2.4.1 is the authority but it has * typos and omissions that make this unimplementable. The * code here is based on experimental results provided by * Takahiro Wagatsuma . * We only support 128-bit keys derived from the NT hash; 40-bit * and 56-bit keys are derived from the LM hash, which besides * being deprecated, has severe security problems. */ { size_t i, passcode_len; unsigned char password_unicode[2 * OTP_MAX_PASSCODE_LEN]; unsigned char password_md[MD4_DIGEST_LENGTH]; unsigned char mppe_keys[32]; /* 0x ASCII(mppe_keys) '\0' */ char mppe_keys_string[2 + (2 * sizeof(mppe_keys)) + 1]; /* Zero the LM-Key sub-field (and padding). */ (void) memset(mppe_keys, 0, sizeof(mppe_keys)); /* * The NT-Key sub-field is MD4(MD4(unicode(password))). * Start by hashing the unicode passcode. * This is broken because unicode chars are machine-ordered, * but the spec (RFC 2433) doesn't say how to prepare * the password for md4 (other than by example values). */ passcode_len = strlen(passcode); for (i = 0; i < passcode_len; ++i) { /* Set the high order 8 bits to 0 (little-endian) */ password_unicode[i * 2] = *passcode++; password_unicode[i * 2 + 1] = 0; } /* first md4 */ (void) MD4(password_unicode, 2 * passcode_len, password_md); /* second md4 */ (void) MD4(password_md, MD4_DIGEST_LENGTH, &mppe_keys[8]); #if 0 /* encoding now handled in lib/radius.c:rad_pwencode() */ { unsigned char md5_md[MD5_DIGEST_LENGTH]; unsigned char encode_buf[AUTH_VECTOR_LEN + MAX_STRING_LEN]; int secretlen; /* Now we must encode the key as User-Password is encoded. */ secretlen = strlen(request->secret); (void) memcpy(encode_buf, request->secret, secretlen); (void) memcpy(encode_buf + secretlen, request->packet->vector, AUTH_VECTOR_LEN); (void) MD5(encode_buf, secretlen + AUTH_VECTOR_LEN, md5_md); for (i = 0; i < 16; ++i) mppe_keys[i] ^= md5_md[i]; (void) memcpy(encode_buf + secretlen, mppe_keys, MD5_DIGEST_LENGTH); (void) MD5(encode_buf, secretlen + MD5_DIGEST_LENGTH, md5_md); for (i = 0; i < 16; ++i) mppe_keys[i + 16] ^= md5_md[i]; } #endif /* 0 */ /* Whew. Now stringify it for pairmake(). */ mppe_keys_string[0] = '0'; mppe_keys_string[1] = 'x'; for (i = 0; i < 32; ++i) (void) sprintf(&mppe_keys_string[i*2+2], "%02X", mppe_keys[i]); vp = pairmake("MS-CHAP-MPPE-Keys", mppe_keys_string, T_OP_EQ); rad_assert(vp != NULL); pairadd(avp, vp); } /* (doing mppe) */ break; /* PWE_MSCHAP */ case PWE_MSCHAP2: { size_t i; unsigned char password_md_md[MD4_DIGEST_LENGTH]; /* * MS-CHAPv2 requires mutual authentication; we must prove * that we know the secret. This is a bit circuitous: set * MD1 = SHA(MD4(MD4(unicode(password)))|NT_RESPONSE|MAGIC1), * MD2 = MSB8(SHA(PEER_CHALLENGE|MS_CHAP_CHALLENGE|USERNAME)), * and finally use SHA(MD1|MD2|MAGIC2) as the authenticator. * The authenticator is returned as the string "S=", * is the authenticator expressed as [uppercase] ASCII. * See RFC 2759. */ { size_t passcode_len; unsigned char password_unicode[2 * OTP_MAX_PASSCODE_LEN]; unsigned char password_md[MD4_DIGEST_LENGTH]; SHA_CTX ctx; unsigned char md1[SHA_DIGEST_LENGTH]; unsigned char md2[SHA_DIGEST_LENGTH]; unsigned char auth_md[SHA_DIGEST_LENGTH]; /* S= ( ASCII(auth_md) ) \0 */ char auth_md_string[2 + (2 * sizeof(auth_md)) + 1]; /* * ugh. The ASCII authenticator (auth_md_string) is sent * along with a single (useless) binary byte (the ID). * So we must "stringify" it again (for pairmake()) since the * binary byte requires the attribute to be of type "octets". */ /* 0x (ID) ( ASCII("S="ASCII(auth_md))) */ char auth_octet_string[2 + 2 + (2 * sizeof(auth_md_string))]; char *username = request->username->strvalue; int username_len = request->username->length; /* "Magic server to client signing constant" */ unsigned char magic1[39] = { 0x4D, 0x61, 0x67, 0x69, 0x63, 0x20, 0x73, 0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x74, 0x6F, 0x20, 0x63, 0x6C, 0x69, 0x65, 0x6E, 0x74, 0x20, 0x73, 0x69, 0x67, 0x6E, 0x69, 0x6E, 0x67, 0x20, 0x63, 0x6F, 0x6E, 0x73, 0x74, 0x61, 0x6E, 0x74 }; /* "Pad to make it do more than one iteration" */ unsigned char magic2[41] = { 0x50, 0x61, 0x64, 0x20, 0x74, 0x6F, 0x20, 0x6D, 0x61, 0x6B, 0x65, 0x20, 0x69, 0x74, 0x20, 0x64, 0x6F, 0x20, 0x6D, 0x6F, 0x72, 0x65, 0x20, 0x74, 0x68, 0x61, 0x6E, 0x20, 0x6F, 0x6E, 0x65, 0x20, 0x69, 0x74, 0x65, 0x72, 0x61, 0x74, 0x69, 0x6F, 0x6E }; /* * Start by hashing the unicode passcode. * This is broken because unicode chars are machine-ordered, * but the spec (RFC 2759) doesn't say how to prepare * the password for md4 (other than by example values). */ passcode_len = strlen(passcode); for (i = 0; i < passcode_len; ++i) { /* Set the high order 8 bits to 0 (little-endian) */ password_unicode[i * 2] = *passcode++; password_unicode[i * 2 + 1] = 0; } /* first md4 */ (void) MD4(password_unicode, 2 * passcode_len, password_md); /* second md4 */ (void) MD4(password_md, MD4_DIGEST_LENGTH, password_md_md); /* MD1 */ SHA1_Init(&ctx); SHA1_Update(&ctx, password_md_md, MD4_DIGEST_LENGTH); SHA1_Update(&ctx, rvp->strvalue + 26, 24); SHA1_Update(&ctx, magic1, sizeof(magic1)); SHA1_Final(md1, &ctx); /* MD2 */ SHA1_Init(&ctx); SHA1_Update(&ctx, rvp->strvalue + 2, 16); SHA1_Update(&ctx, cvp->strvalue, 16); SHA1_Update(&ctx, username, username_len); SHA1_Final(md2, &ctx); /* The Authenticator */ SHA1_Init(&ctx); SHA1_Update(&ctx, md1, SHA_DIGEST_LENGTH); SHA1_Update(&ctx, md2, 8); SHA1_Update(&ctx, magic2, sizeof(magic2)); SHA1_Final(auth_md, &ctx); /* String conversion. */ auth_md_string[0] = 'S'; auth_md_string[1] = '='; for (i = 0; i < sizeof(auth_md); ++i) (void) sprintf(&auth_md_string[i * 2 + 2], "%02X", auth_md[i]); /* And then octet conversion. Ugh! */ auth_octet_string[0] = '0'; auth_octet_string[1] = 'x'; (void) sprintf(&auth_octet_string[2], "%02X", rvp->strvalue[0]); for (i = 0; i < sizeof(auth_md_string) - 1; ++i) (void) sprintf(&auth_octet_string[i * 2 +4], "%02X", auth_md_string[i]); vp = pairmake("MS-CHAP2-Success", auth_octet_string, T_OP_EQ); rad_assert(vp != NULL); pairadd(avp, vp); } /* Generate mutual auth info. */ /* * Now, set some MPPE related attributes. */ vp = pairmake("MS-MPPE-Encryption-Policy", otp_mppe_policy[opt->mschapv2_mppe_policy], T_OP_EQ); rad_assert(vp != NULL); pairadd(avp, vp); vp = pairmake("MS-MPPE-Encryption-Types", otp_mppe_types[opt->mschapv2_mppe_types], T_OP_EQ); rad_assert(vp != NULL); pairadd(avp, vp); /* If no MPPE, we're done. */ if (!opt->mschapv2_mppe_policy) return; /* * Generate the MPPE initial session key, per RFC 3079. * (Although, RFC 2548 leaves us guessing at how to generate this.) * For MS-CHAPv2 we support all key lengths (40-, 56- and 128-bit), * although MPPE via RADIUS supports only 40- and 128-bit keys. * This is a bit more complicated than MS-CHAP. Start by generating * a "master session key" * MSB16(SHA(NTPasswordHashHash|NT_RESPONSE|MAGIC1)), where * NTPasswordHashHash is MD4(MD4(unicode(password))), NT_RESPONSE * is from the MS-CHAP2-Response attribute, and MAGIC1 is a * constant from RFC 3079. Then, we derive asymmetric send/receive * keys from the master session key. The "master send key" is * MSBx(SHA(MASTERKEY|SHSPAD1|MAGIC3|SHSPAD2)), * and the "master receive key" is * MSBx(SHA(MASTERKEY|SHSPAD1|MAGIC2|SHSPAD2)), where * MASTERKEY is the "master session key" generated above, and the * other values are constants from RFC 3079. MSBx is the x-most * significant bytes, where x is 5, 7, or 16 as appropriate for * the desired key length. We always generate 16 byte (128-bit) * keys, the NAS is required to truncate as needed. */ { /* These constants and key vars are named from RFC 3079. */ /* "This is the MPPE Master Key" */ unsigned char Magic1[27] = { 0x54, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68, 0x65, 0x20, 0x4d, 0x50, 0x50, 0x45, 0x20, 0x4d, 0x61, 0x73, 0x74, 0x65, 0x72, 0x20, 0x4b, 0x65, 0x79 }; /* "On the client side, this is the send key; " "on the server side, it is the receive key." */ unsigned char Magic2[84] = { 0x4f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x69, 0x65, 0x6e, 0x74, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20, 0x74, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73, 0x65, 0x6e, 0x64, 0x20, 0x6b, 0x65, 0x79, 0x3b, 0x20, 0x6f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73, 0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20, 0x69, 0x74, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68, 0x65, 0x20, 0x72, 0x65, 0x63, 0x65, 0x69, 0x76, 0x65, 0x20, 0x6b, 0x65, 0x79, 0x2e }; /* "On the client side, this is the receive key; " "on the server side, it is the send key." */ unsigned char Magic3[84] = { 0x4f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x69, 0x65, 0x6e, 0x74, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20, 0x74, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68, 0x65, 0x20, 0x72, 0x65, 0x63, 0x65, 0x69, 0x76, 0x65, 0x20, 0x6b, 0x65, 0x79, 0x3b, 0x20, 0x6f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73, 0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20, 0x69, 0x74, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73, 0x65, 0x6e, 0x64, 0x20, 0x6b, 0x65, 0x79, 0x2e }; unsigned char SHSpad1[40] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; unsigned char SHSpad2[40] = { 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2 }; unsigned char MasterKey[16]; unsigned char MasterSendKey[16]; unsigned char MasterReceiveKey[16]; SHA_CTX ctx; unsigned char sha_md[SHA_DIGEST_LENGTH]; #if 0 /* salting/encoding now handled in lib/radius.c:tunnel_pwencode() */ unsigned char md5_md[MD5_DIGEST_LENGTH]; /* From RFC 2548: S R A */ unsigned char encode_buf[MAX_STRING_LEN + AUTH_VECTOR_LEN + 2]; int secretlen; /* A useless value required by RFC 2548. */ unsigned char salt[2]; unsigned char mppe_key[32]; /* 1 + 16 + padding */ /* 0x ( ASCII(salt) ) */ unsigned char mppe_key_string[2 + (2 * sizeof(salt)) + /* ( ASCII(mppe_key) ) \0 */ (2 * sizeof(mppe_key)) + 1]; #else /* 0 */ /* 0x ( ASCII(mppe_key) ) \0 */ unsigned char mppe_key_string[2 + (2 * sizeof(MasterKey)) + 1]; #endif /* else !0 */ /* Generate the master session key. */ SHA1_Init(&ctx); SHA1_Update(&ctx, password_md_md, MD4_DIGEST_LENGTH); SHA1_Update(&ctx, rvp->strvalue + 26, 24); SHA1_Update(&ctx, Magic1, sizeof(Magic1)); SHA1_Final(sha_md, &ctx); (void) memcpy(MasterKey, sha_md, 16); /* Generate the master send key. */ SHA1_Init(&ctx); SHA1_Update(&ctx, MasterKey, 16); SHA1_Update(&ctx, SHSpad1, 40); SHA1_Update(&ctx, Magic3, sizeof(Magic3)); SHA1_Update(&ctx, SHSpad2, 40); SHA1_Final(sha_md, &ctx); (void) memcpy(MasterSendKey, sha_md, 16); /* Generate the master receive key. */ SHA1_Init(&ctx); SHA1_Update(&ctx, MasterKey, 16); SHA1_Update(&ctx, SHSpad1, 40); SHA1_Update(&ctx, Magic2, sizeof(Magic3)); SHA1_Update(&ctx, SHSpad2, 40); SHA1_Final(sha_md, &ctx); (void) memcpy(MasterReceiveKey, sha_md, 16); /* * Now, generate the MS-MPPE-Send-Key attribute. */ #if 0 /* Setup the salt value. */ salt[0] = 0x80; salt[1] = 0x01; /* Encode the key. */ (void) memset(mppe_key, 0, sizeof(mppe_key)); mppe_key[0] = 16; /* length */ (void) memcpy(&mppe_key[1], MasterSendKey, 16); secretlen = strlen(request->secret); (void) memcpy(encode_buf, request->secret, secretlen); (void) memcpy(encode_buf + secretlen, request->packet->vector, AUTH_VECTOR_LEN); (void) memcpy(encode_buf + secretlen + 16, salt, 2); (void) MD5(encode_buf, secretlen + AUTH_VECTOR_LEN + 2, md5_md); for (i = 0; i < 16; ++i) mppe_key[i] ^= md5_md[i]; (void) memcpy(encode_buf + secretlen, mppe_key, 16); (void) MD5(encode_buf, secretlen + 16, md5_md); for (i = 0; i < 16; ++i) mppe_key[i + 16] ^= md5_md[i]; /* Whew. Now stringify it for pairmake(). */ mppe_key_string[0] = '0'; mppe_key_string[1] = 'x'; (void) sprintf(&mppe_key_string[2], "%02X", salt[0]); (void) sprintf(&mppe_key_string[4], "%02X", salt[1]); for (i = 0; i < sizeof(mppe_key); ++i) (void) sprintf(&mppe_key_string[i*2+6], "%02X", mppe_key[i]); #else /* 0 */ mppe_key_string[0] = '0'; mppe_key_string[1] = 'x'; for (i = 0; i < sizeof(MasterSendKey); ++i) (void) sprintf(&mppe_key_string[i*2+2], "%02X", MasterSendKey[i]); #endif /* else !0 */ vp = pairmake("MS-MPPE-Send-Key", mppe_key_string, T_OP_EQ); rad_assert(vp != NULL); pairadd(avp, vp); /* * Generate the MS-MPPE-Recv-Key attribute. */ #if 0 /* Setup the salt value. */ salt[0] = 0x80; salt[1] = 0x02; /* Encode the key. */ (void) memset(mppe_key, 0, sizeof(mppe_key)); mppe_key[0] = 16; /* length */ (void) memcpy(&mppe_key[1], MasterReceiveKey, 16); secretlen = strlen(request->secret); (void) memcpy(encode_buf, request->secret, secretlen); (void) memcpy(encode_buf + secretlen, request->packet->vector, AUTH_VECTOR_LEN); (void) memcpy(encode_buf + secretlen + 16, salt, 2); (void) MD5(encode_buf, secretlen + AUTH_VECTOR_LEN + 2, md5_md); for (i = 0; i < 16; ++i) mppe_key[i] ^= md5_md[i]; (void) memcpy(encode_buf + secretlen, mppe_key, 16); (void) MD5(encode_buf, secretlen + 16, md5_md); for (i = 0; i < 16; ++i) mppe_key[i + 16] ^= md5_md[i]; /* Whew. Now stringify it for pairmake(). */ mppe_key_string[0] = '0'; mppe_key_string[1] = 'x'; (void) sprintf(&mppe_key_string[2], "%02X", salt[0]); (void) sprintf(&mppe_key_string[4], "%02X", salt[1]); for (i = 0; i < sizeof(mppe_key); ++i) (void) sprintf(&mppe_key_string[i*2+6], "%02X", mppe_key[i]); #else /* 0 */ mppe_key_string[0] = '0'; mppe_key_string[1] = 'x'; for (i = 0; i < sizeof(MasterReceiveKey); ++i) (void) sprintf(&mppe_key_string[i*2+2], "%02X", MasterReceiveKey[i]); #endif /* else !0 */ vp = pairmake("MS-MPPE-Recv-Key", mppe_key_string, T_OP_EQ); rad_assert(vp != NULL); pairadd(avp, vp); } /* (doing mppe) */ } /* PWE_MSCHAP2 */ break; /* PWE_MSCHAP2 */ } /* switch (pwe) */ return; }