The invention relates to a revocable key external 
package decryption method based on content attributes. For a 
trusted authority, 1, initialization is carried out, and 
system parameters are output; 2, a 
random number generation algorithm operates; 3, a collision-resistant 
Hash function is selected, and the Hash value is calculated; 4, a public key and a main key are calculated; 5, the random number is selected, and exponentiation calculation and multiplication are carried out; 6, the collision-resistant 
Hash function operates, the exponentiation operation is carried out, and a decryption key is obtained. For a data holder, 7, AES data 
encryption is carried out; 8, an 
access control matrix is generated; 9, a random number is selected, and an inner product is calculated; 10, multiplication, exponentiation and exclusive-or operation is operated, and ciphertexts are obtained. For a decryption operator, 11, a decryption request and a transformation key are sent. For a mobile storage serve provider, 12, CT2 is sent to an external 
package decryption agency. For the external 
package decryption agency, 13, the transformation key is utilized, and the transformation 
ciphertext is calculated. For the decryption operator, 14, a conversation key is obtained through calculation; 15, AES 
data decryption is carried out.