diff options
Diffstat (limited to 'source3/libsmb/smbencrypt.c')
| -rw-r--r-- | source3/libsmb/smbencrypt.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/source3/libsmb/smbencrypt.c b/source3/libsmb/smbencrypt.c index a8a88a8a7e..0742976635 100644 --- a/source3/libsmb/smbencrypt.c +++ b/source3/libsmb/smbencrypt.c @@ -782,3 +782,117 @@ WERROR decode_wkssvc_join_password_buffer(TALLOC_CTX *mem_ctx, return WERR_OK; } + +DATA_BLOB decrypt_drsuapi_blob(TALLOC_CTX *mem_ctx, + const DATA_BLOB *session_key, + bool rcrypt, + uint32_t rid, + const DATA_BLOB *buffer) +{ + DATA_BLOB confounder; + DATA_BLOB enc_buffer; + + struct MD5Context md5; + uint8_t _enc_key[16]; + DATA_BLOB enc_key; + + DATA_BLOB dec_buffer; + + uint32_t crc32_given; + uint32_t crc32_calc; + DATA_BLOB checked_buffer; + + DATA_BLOB plain_buffer; + + /* + * the combination "c[3] s[1] e[1] d[0]..." + * was successful!!!!!!!!!!!!!!!!!!!!!!!!!! + */ + + /* + * the first 16 bytes at the beginning are the confounder + * followed by the 4 byte crc32 checksum + */ + if (buffer->length < 20) { + return data_blob_const(NULL, 0); + } + confounder = data_blob_const(buffer->data, 16); + enc_buffer = data_blob_const(buffer->data + 16, buffer->length - 16); + + /* + * build the encryption key md5 over the session key followed + * by the confounder + * + * here the gensec session key is used and + * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key! + */ + enc_key = data_blob_const(_enc_key, sizeof(_enc_key)); + MD5Init(&md5); + MD5Update(&md5, session_key->data, session_key->length); + MD5Update(&md5, confounder.data, confounder.length); + MD5Final(enc_key.data, &md5); + + /* + * copy the encrypted buffer part and + * decrypt it using the created encryption key using arcfour + */ + dec_buffer = data_blob_talloc(mem_ctx, enc_buffer.data, enc_buffer.length); + if (!dec_buffer.data) { + return data_blob_const(NULL, 0); + } + SamOEMhashBlob(dec_buffer.data, dec_buffer.length, &enc_key); + + /* + * the first 4 byte are the crc32 checksum + * of the remaining bytes + */ + crc32_given = IVAL(dec_buffer.data, 0); + crc32_calc = crc32_calc_buffer((const char *)dec_buffer.data + 4 , dec_buffer.length - 4); + if (crc32_given != crc32_calc) { + DEBUG(1,("CRC32: given[0x%08X] calc[0x%08X]\n", + crc32_given, crc32_calc)); + return data_blob_const(NULL, 0); + } + checked_buffer = data_blob_talloc(mem_ctx, dec_buffer.data + 4, dec_buffer.length - 4); + if (!checked_buffer.data) { + return data_blob_const(NULL, 0); + } + + /* + * some attributes seem to be in a usable form after this decryption + * (supplementalCredentials, priorValue, currentValue, trustAuthOutgoing, + * trustAuthIncoming, initialAuthOutgoing, initialAuthIncoming) + * At least supplementalCredentials contains plaintext + * like "Primary:Kerberos" (in unicode form) + * + * some attributes seem to have some additional encryption + * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory + * + * it's the sam_rid_crypt() function, as the value is constant, + * so it doesn't depend on sessionkeys. + */ + if (rcrypt) { + uint32_t i, num_hashes; + + if ((checked_buffer.length % 16) != 0) { + return data_blob_const(NULL, 0); + } + + plain_buffer = data_blob_talloc(mem_ctx, checked_buffer.data, checked_buffer.length); + if (!plain_buffer.data) { + return data_blob_const(NULL, 0); + } + + num_hashes = plain_buffer.length / 16; + for (i = 0; i < num_hashes; i++) { + uint32_t offset = i * 16; + sam_pwd_hash(rid, checked_buffer.data + offset, plain_buffer.data + offset, 0); + } + } else { + plain_buffer = checked_buffer; + } + + return plain_buffer; +} + + |