In Microsoft Excel 95 and earlier versions, the password to open is converted to a 16-bit key that can be instantly cracked. In Excel 97/2000 the password is converted to a 40-bit key, which can also be cracked very quickly using modern equipment. As regards services that use rainbow tables (e.g. Password-Find), it takes up to several seconds to remove protection. In addition, password-cracking programs can brute-force attack passwords at a rate of hundreds of thousands of passwords a second, which not only lets them decrypt a document but also find the original password.