Method for protecting encrypted control word, hardware security module, main chip and terminal

A method for protecting an encrypted control word, comprising:

• generating an activation request message and transmitting the activation request message to a front end, wherein the activation request message comprises at least of:
• an identifier of a main chip, a conditional access certificate and a chip certificate for a hardware security device;
• receiving an activation message transmitted from the front end, and transmitting the activation message to the hardware security device, wherein the activation message comprises at least one of:
• a pairing key, a re-encryption key and a hardware security device root key, and the pairing key, the re-encryption key and the hardware security device root key in the activation message are distributed by the front end based on the activation request message;
• establishing a security authentication channel between the main chip and the hardware security device based on the pairing key;
• receiving the encrypted control word, a scrambled content, a main chip entitlement management message and a hardware security device entitlement management message transmitted from the front end;
• transmitting the hardware security device entitlement management message and the encrypted control word to the hardware security device through the security authentication channel, so that the hardware security device decrypts, based on the hardware security device entitlement management message and the hardware security device root key stored in the hardware security device, the encrypted control word to obtain a control word, and reencrypts the control word based on the re-encryption key stored in the hardware security device to obtain a reencrypted control word;
• and
• receiving the reencrypted control word transmitted from the hardware security device through the security authentication channel, decrypting, based on a main chip root key derived from the main chip and the main chip entitlement management message, the reencrypted control word to obtain the control word so that the scrambled content is descrambled based on the control word.

A hardware security device, applied to a downloadable conditional access system, comprising a processor and a storage device for storing computer executable instructions that when executed by the processor cause the processor to:

• receive an activation message transmitted from a main chip, wherein the activation message comprises at least of:
• a pairing key, the re-encryption key and the hardware security device root key;
• store the re-encryption key and the hardware security device root key into the storage device, and establish a security authentication channel between the hardware security device and the main chip based on the pairing key;
• receive a hardware security device entitlement management message and the encrypted control word transmitted from the main chip through the security authentication channel, wherein the hardware security device entitlement management message comprises a key for decrypting the encrypted control word;
• decrypt, based on the hardware security device entitlement management message and the hardware security device root key, the encrypted control word to obtain a control word;
• reencrypt the control word based on the re-encryption key to obtain a reencrypted control word;
• transmit the reencrypted control word to the main chip through the security authentication channel, so that the main chip decrypts, based on a main chip entitlement management message transmitted from the front end, the reencrypted control word to obtain the control word, wherein the main chip entitlement management message comprises a key for decrypting the reencrypted control word.

A main chip, applied to a downloadable conditional access system, comprising a processor and a storage device for storing computer executable instructions that when executed by the processor cause the processor to:

• generate an activation request message and transmit the activation request message to a front end, wherein the activation request message comprises at least one of:
• an identifier of the main chip, a conditional access certificate and a chip certificate for a hardware security device;
• receive an activation message transmitted from the front end, and transmit the activation message to the hardware security device, wherein the activation message comprises at least one of:
• a pairing key, the re-encryption key and the hardware security device root key, and the pairing key, the re-encryption key and the hardware security device root key in the activation message are distributed by the front end based on the activation request message;
• establish a security authentication channel between the main chip and the hardware security device based on the pairing key;
• receive an encrypted control word, a scrambled content, a main chip entitlement management message and a hardware security device entitlement management message transmitted from the front end;
• transmit the hardware security device entitlement management message and the encrypted control word to the hardware security device through the security authentication channel, so that the hardware security device decrypts, based on the hardware security device entitlement management message and a hardware security device root key stored in the hardware security device, the encrypted control word to obtain a control word, and reencrypts the control word based on the re-encryption key stored in the hardware security device to obtain a reencrypted control word;
• and
• receive the reencrypted control word transmitted from the hardware security device through the security authentication channel;
• and
• decrypt, based on a main chip root key derived from the main chip and the main chip entitlement management message, the reencrypted control word to obtain the control word so that the scrambled content is descrambled based on the control word.