Subscription concealed identifier privacy

A method of operating a network node in a wireless communication network, the method comprising:

• determining a padding technique usable by a user equipment (UE) in the wireless communication network to insert a padding bitstring in a field of an identifier associated with the UE prior to the UE encrypting the identifier, wherein the identifier is a subscription permanent identifier (SUPI), wherein fields of the SUPI comprise at least one of:
• a mobile subscriber identification number (MSIN), a username, a routing identifier, a public key identifier, or a scheme identifier, wherein the padding technique comprises padding at least one of:
• the MSIN, the username, the routing identifier, the public key identifier, or the scheme identifier, wherein the padding technique comprises inserting a delimiter before or after the padding bitstring, the delimiter being a predetermined bitstring that separates the padding bitstring from unpadded content of the field of the identifier, wherein the delimiter comprises a first delimiter and a second delimiter, and wherein inserting the delimiter comprises inserting the first delimiter before the padding bitstring and inserting the second delimiter after the padding bitstring;
• receiving a concealed padded identifier from the UE;
• decrypting the concealed padded identifier to generate a padded identifier;
• and
• determining content of the identifier separate from the padding bitstring based on the padding technique.

A user equipment (UE) operating in a wireless communication network comprising:

• processing circuitry;
• and
• memory coupled to the processing circuitry and having instructions stored therein that are executable by the processing circuitry to cause the UE to perform operations comprising:
• generating a padded identifier by inserting a padding bitstring in a field of an identifier associated with the UE, wherein the identifier is a subscription permanent identifier (SUPI), wherein fields of the SUPI comprise at least one of:
• a mobile subscriber identification number (MSIN), a username, a routing identifier, a public key identifier, or a scheme identifier, wherein generating the padded identifier comprises padding at least one of:
• the MSIN, the username, the routing identifier, the public key identifier, or the scheme identifier, wherein generating the padded identifier comprises inserting a delimiter before or after the padding bitstring, the delimiter being a predetermined bitstring that separates the padding bitstring from unpadded content of the field of the identifier, wherein the delimiter comprises a first delimiter and a second delimiter, and wherein inserting the delimiter comprises inserting the first delimiter before the padding bitstring and inserting the second delimiter after the padding bitstring;
• encrypting the padded identifier to generate a concealed padded identifier;
• and
• transmitting the concealed padded identifier to a network node operating in the wireless communication network.

A network node operating in a wireless communication network, the network node comprising:

• processing circuitry;
• and
• memory coupled to the processing circuitry having instructions stored therein that are executable by the processing circuitry to cause the network node to perform operations comprising:
• determining a padding technique usable by a user equipment (UE) in the wireless communication network to insert a padding bitstring in a field of an identifier associated with the UE prior to the UE encrypting the identifier, wherein the identifier is a subscription permanent identifier (SUPI), wherein fields of the SUPI comprise at least one of:
• a mobile subscriber identification number (MSIN), a username, a routing identifier, a public key identifier, or a scheme identifier, wherein the padding technique comprises padding at least one of:
• the MSIN, the username, the routing identifier, the public key identifier, or the scheme identifier, wherein the padding technique comprises inserting a delimiter before or after the padding bitstring, the delimiter being a predetermined bitstring that separates the padding bitstring from unpadded content of the field of the identifier, wherein the delimiter comprises a first delimiter and a second delimiter, and wherein inserting the delimiter comprises inserting the first delimiter before the padding bitstring and inserting the second delimiter after the padding bitstring;
• receiving a concealed padded identifier from the UE;
• decrypting the concealed padded identifier to generate a padded identifier;
• and
• determining content of the identifier separate from the padding bitstring based on the padding technique.