A method comprising: associating, by a server computer (110, 210), a credential or a token with device information within a database, wherein the credential or the token is from a portable transaction device (108, 208, 401) of a user and wherein the device information is from a portable communication device (102, 202, 301, 401) of the user; receiving, by the server computer (110, 210), the device information from the portable communication device (102, 202, 301, 401); searching, by the server computer (110, 210), the database for the credential or the token associated with the device information; hashing, by the server computer (110, 210), at least the credential or the token to form a first cryptographic pattern; transmitting, by the server computer (110, 210), the first cryptographic pattern to the portable communication device (102, 202, 301, 401); receiving, by the server computer (110, 210) and from the portable communication device (102, 202, 301), a base station identifier, wherein the base station identifier is received by the portable communication device (101, 202, 301) from a base station (104, 204) associated with a resource provider location when the portable communication device (101, 202, 301) is located at the resource provider location, and wherein the base station identifier uniquely identifies the resource provider location; hashing, by the server computer (110, 210), at least the first cryptographic pattern and the base station identifier to form a second cryptographic pattern; receiving, by the server computer (110, 210), from an access device (106, 206, 404) in a transaction, an authorization request message, wherein the authorization request message includes at least a portion of another cryptographic pattern generated by the access device (106, 206, 404) based on the credential or the token received from the portable transaction device (108, 208, 401) and the base station identifier received from the base station; and analyzing, by the server computer (110, 210), the authorization request message to determine that the user of the portable communication device (102, 202, 301, 401) and the portable transaction device (108, 208, 401) is conducting the transaction at the access device (106, 206, 404) by determining that the authorization request message includes at least a portion of the another cryptographic pattern and determining that the second cryptographic pattern matches to the at least a portion of the another cryptographic pattern. associating, by a server computer (110, 210), a credential or a token with device information within a database, wherein the credential or the token is from a portable transaction device (108, 208, 401) of a user and wherein the device information is from a portable communication device (102, 202, 301, 401) of the user; receiving, by the server computer (110, 210), the device information from the portable communication device (102, 202, 301, 401); searching, by the server computer (110, 210), the database for the credential or the token associated with the device information; hashing, by the server computer (110, 210), at least the credential or the token to form a first cryptographic pattern; transmitting, by the server computer (110, 210), the first cryptographic pattern to the portable communication device (102, 202, 301, 401); receiving, by the server computer (110, 210) and from the portable communication device (102, 202, 301), a base station identifier, wherein the base station identifier is received by the portable communication device (101, 202, 301) from a base station (104, 204) associated with a resource provider location when the portable communication device (101, 202, 301) is located at the resource provider location, and wherein the base station identifier uniquely identifies the resource provider location; hashing, by the server computer (110, 210), at least the first cryptographic pattern and the base station identifier to form a second cryptographic pattern; receiving, by the server computer (110, 210), from an access device (106, 206, 404) in a transaction, an authorization request message, wherein the authorization request message includes at least a portion of another cryptographic pattern generated by the access device (106, 206, 404) based on the credential or the token received from the portable transaction device (108, 208, 401) and the base station identifier received from the base station; and analyzing, by the server computer (110, 210), the authorization request message to determine that the user of the portable communication device (102, 202, 301, 401) and the portable transaction device (108, 208, 401) is conducting the transaction at the access device (106, 206, 404) by determining that the authorization request message includes at least a portion of the another cryptographic pattern and determining that the second cryptographic pattern matches to the at least a portion of the another cryptographic pattern.