Host card emulation systems and methods

1. A method comprising:

detecting, by a processor of a user device, a point of sale;

receiving, by the processor, a personal identification number (PIN);

generating, by the processor, a PIN based key using a message digest of the PIN;

decrypting, by the processor, a data encryption key (DEK) using the PIN based key;

generating, by the processor, a DEK based dynamic key using the PIN based key;

decrypting, by the processor, a session key using the DEK based dynamic key; retrieving, by the processor and while the user device is automatically connected to a network, a limited use purchase credential (LUPC) that authorizes a purchase,

wherein the session key is stored on the user device,

wherein the session key includes the LUPC,

wherein the session key is used for a plurality of transactions,

generating, by the processor, a cryptogram from the session key while the user device is disconnected from the network; and

sending, by the processor, the cryptogram to the point of sale while the user device is disconnected from the network,

wherein the LUPC is used to authorize the purchase while the user device is disconnected from the network.

2. The method of claim 1 , further comprising obfuscating, by the processor, encryption protocols used to decrypt the DEK and the session key.

3. The method of claim 1 , further comprising deleting, by the processor, the session key after a predetermined duration.

4. The method of claim 1 , further comprising deleting, by the processor, the session key in response to the sending, by the processor, the cryptogram to the point of sale.

5. The method of claim 1 , further comprising receiving, by the processor, a new session key from an HCE cloud component in response to detecting a number of session keys stored on the user device below a threshold.

6. The method of claim 5 , further comprising encrypting, by the processor, the new session key using the PIN based key.

7. The method of claim 6 , further comprising encrypting, by the processor, the new session key using the DEK based dynamic key.

8. The method of claim 1 , wherein the cryptogram from the session key occurs while the cryptogram is transmitted to the point of sale without using the Internet.

9. The method of claim 1 , wherein the retrieving the LUPC comprises retrieving the LUPC from at least one of an issuer server or a cloud network.

10. A user device, comprising:

a processor of the user device;

a tangible, non-transitory memory configured to communicate with the processor, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the processor, cause the processor to perform operations comprising:

detecting, by the processor, a point of sale;

receiving, by the processor, a personal identification number (PIN);

generating, by the processor, a PIN based key using a message digest of the PIN;

decrypting, by the processor, a data encryption key (DEK) using the PIN based key;

generating, by the processor, a DEK based dynamic key using the PIN based key;

decrypting, by the processor, a session key using the DEK based dynamic key;

retrieving, by the processor and while the user device is automatically connected to a network, a limited use purchase credential (LUPC) that authorizes a purchase,

wherein the session key is stored on the user device,

wherein the session key includes the LUPC,

wherein the session key is used for a plurality of transactions,

generating, by the processor, a cryptogram from the session key while the user device is disconnected from the network; and

sending, by the processor, the cryptogram to the point of sale while the user device is disconnected from the network,

wherein the LUPC is used to authorize the purchase while the user device is disconnected from the network.

11. The computer-based system of claim 10 , further comprising obfuscating, by the processor, encryption protocols used to decrypt the DEK and the session key.

12. The computer-based system of claim 10 , further comprising deleting, by the processor, the session key after a predetermined duration.

13. The computer-based system of claim 10 , further comprising deleting, by the processor, the session key in response to the sending, by the processor, the cryptogram to the point of sale.

14. The computer-based system of claim 10 , further comprising receiving, by the processor, a new session key from an HCE cloud component in response to detecting a number of session keys stored on the user device below a threshold.

15. The computer-based system of claim 14 , further comprising encrypting, by the processor, the new session key using the PIN based key.

16. The computer-based system of claim 15 , further comprising encrypting, by the processor, the new session key using the DEK based dynamic key.

17. The computer-based system of claim 10 , wherein the cryptogram from the session key occurs while the cryptogram is transmitted to the point of sale without using the Internet.

18. An article of manufacture including a non-transitory, tangible computer readable storage medium having instructions stored thereon that, in response to execution by a processor of a user device, cause the processor to perform operations comprising:

detecting, by the processor, a point of sale;

receiving, by the processor, a personal identification number (PIN);

generating, by the processor, a PIN based key using a message digest of the PIN;

decrypting, by the processor, a data encryption key (DEK) using the PIN based key;

generating, by the processor, a DEK based dynamic key using the PIN based key;

decrypting, by the processor, a session key using the DEK based dynamic key; retrieving, by the processor and while the user device is automatically connected to a network, a limited use purchase credential (LUPC) that authorizes a purchase,

wherein the session key is stored on the user device,

wherein the session key includes the LUPC,

wherein the session key is used for a plurality of transactions,

generating, by the processor, a cryptogram from the session key while the user device is disconnected from the network; and

sending, by the processor, the cryptogram to the point of sale while the user device is disconnected from the network,

wherein the LUPC is used to authorize the purchase while the user device is disconnected from the network.

19. The article of claim 18 , further comprising obfuscating, by the processor, encryption protocols used to decrypt the DEK and the session key.

20. The article of claim 18 , further comprising deleting, by the processor, the session key after a predetermined duration.