[Samsung Galaxy Nexus] gonzalo-gonads:
Ok so I've been messing with nfc on my galaxy nexus and I wanted to ask some questions. Our school has doors which you can only pass if you swipe it with your key tag, students have limited access compared to teachers. All the tags are of type Mifare Classic 1K, and have individual uid's etc which I guess are stored on the school system along with permissions.

If I get a hold of the information from a teachers tag, could I copy the tag and get the same privileges?

Here is the code I swiped off my own one from NFCtaginfo

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
<InfoDump application="NFC TagInfo" version="1.08">
<Tag rfTechnology="Type A (ISO/IEC 14443 Type A)">
<GeneralInformation>
<Value name="uid" description="UID[4]">ab6a6331</Value>
<Value name="rfTechnology" description="RF technology">Type A (ISO/IEC 14443 Type A)</Value>
<Value name="tagType" description="Tag type">Mifare Classic 1K</Value>
<Value name="atqa" description="ATQA">0004</Value>
<Value name="sak" description="SAK">08</Value>
<Value name="targetTechClasses" description="Target technology classes (Android)">android.nfc.tech.MifareClassic,
android.nfc.tech.NfcA</Value>
</GeneralInformation>
<MemoryTag type="Mifare Classic 1K">
<GeneralInformation>
<Value name="memorySize" description="Memory size">1024 Byte</Value>
<Value name="blockSize" description="Block size">16 Byte</Value>
<Value name="numberOfBlocks" description="Number of blocks">64</Value>
<Value name="numberOfSectors" description="Number of sectors">16</Value>
</GeneralInformation>
<Data unit="sector:block">
<Sector index="0">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">ab6a63319388040047c13979dd003908</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="1">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="2">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="3">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="4" trailerAccess="true">
<Block index="0" readError="true" />
<Block index="1" readError="true" />
<Block index="2" readError="true" />
<Block index="3" readError="true" />
</Sector>
<Sector index="5">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="6">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="7">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="8">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="9">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="10">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="11">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="12">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="13">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="14">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
<Sector index="15">
<Block index="0" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="1" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="2" accessRead="keyA" accessWrite="keyA" accessIncrement="keyA" accessDecrementTransferRestore="keyA">00000000000000000000000000000000</Block>
<Block index="3" accessReadAccessBits="keyA" accessWriteAccessBits="keyA" accessReadKeyA="never" accessWriteKeyA="keyA" accessReadKeyB="keyA" accessWriteKeyB="keyA">ffffffffffffff078000ffffffffffff</Block>
</Sector>
</Data>
</MemoryTag>
</Tag>
</InfoDump>

Thanks