I can tell you that the ones we have to get into our halls NEVER bloody work!!!! so yeah, they're secure in that you cant get anywhere you need with them...
swipe cars have a magnetic stripe with a number encoded on it, whenever the card is used, the number is sent to a database, which will then match the number to a person
Swipe cards use a strip of a fero magnetic material to store its data, very similar to a tape recorder. Typically a swipe card holds an identification number and possibly an access code. In terms of security, it all depends on teh format of the data. It is quite easy to read the data of a swipe card, and it can even be done with a home made device built from scrap pieces of a tape recorder hooked up to a computer (Ok, this requires some technical skills, but the general principle is quite simple). Therefore, the security of a swipe card all depends on the encoding of the data in the card. As swipe card typically hold just an ID and an access code, it should not be a great problem to implement an encryption system. Thus if the data is encrypted with 1028 bit RSA encryption, it is virtually impossible for an infiltrator to read the data of a swipe card. If even greater security is required, one could exploit the fact that the ID and access codes are fairly short and use a code key ID together with a random numbers database making the encryption theoretically impossible to crack. The only security hole in such a system which can be considered to be a feature of teh storage medium is in such a cse the electromagnetic signal generated when you swipe the card across the terminal. In general, infiltrators are more likely to exploit security holes ascociated with the terminal mechanism or conventional surveilance than to crack teh storage medium of a swipe card.
Having said that, many swipe cards used comercially have little or no encryption implemented. As an example, the magnetic ATM cards used in many countries were developed at a time when noone even considered the possibility for a thief to aquire the technology neccessary to read a magnetic stripe, and thus many of tehse are not encrypted at all. Technological progress have however made it relatively easy for a private person to create such a device, and thus it is fairly straight forward for organised criminals to read your bank account number as well as pin code straight from a magnetic ATM card.
I do not know the exact storage capacity of a swipe card, but my best guess is that the maximum capacity per centimeter of magnetic material is less than that of a normal audio tape. Mosts systems tend to store an ID code together with a pin number and an expiration date. I suggest you do a web search if you need more information.
Thus if the data is encrypit is fairly straight forward for organised criminals to read your bank account number as well as pin code straight from a magnetic ATM card..
Is that true? - I was under the impression the magnetic strip only carried the data written on the card such as card number, expiary dates and issue numbers.