Reissue of cryptographic credentials

A system for effecting reissue of a cryptographic credential certifying a set of attributes, the credential being initially bound to a first secret key stored in a first tamper-resistant processing device, the system comprising:

• a second tamper-resistant device having a first memory and card control logic, the first memory storing a second secret key;
• and
• a first computing system in communication with the second tamper-resistant device, the computing system having a communications interface and credential logic, wherein the card control logic and the credential logic are configured to cause the system to perform a method comprising:
• blinding the second secret key to produce a blinded key;
• producing a credential template token comprising a backup token and the blinded key, the backup token stored in a backup memory, the backup token comprising a commitment to said set of attributes and first proof data permitting verification that the set of attributes in said commitment corresponds to the set of attributes certified by said credential, the backup token produced using the first tamper-resistant device;
• sending, using the communications interface, the credential template token to a credential issuer;
• receiving, using the communications interface, a pre-credential from the credential issuer, the pre-credential generated by the credential issuer in response to the credential issuer verifying the credential template token, the pre-credential generated using information in the credential template token;
• and
• completing the pre-credential to produce a reissued credential, the reissued credential bound to the second secret key.

A system for effecting reissue of a cryptographic credential certifying a set of attributes, the credential being initially bound to a first secret key stored in a first tamper-resistant processing device, the system comprising:

• a second tamper-resistant device having a first memory and card control logic, the first memory storing a second secret key;
• and
• a user apparatus in communication with the second tamper-resistant device, the user apparatus having a first communications interface and credential logic;
• and
• a credential issuer having a second communications interface and issuer logic, wherein the card control logic, the credential logic, and the issuer logic are configured to cause the system to perform a method comprising:
• at the second tamper-resistant device, blinding the second secret key to produce a blinded key;
• producing a credential template token comprising a backup token and the blinded key, the backup token stored in a backup memory, the backup token comprising a commitment to said set of attributes and first proof data permitting verification that the set of attributes in said commitment corresponds to the set of attributes certified by said credential, the backup token produced using the first tamper-resistant device;
• sending the credential template token to a credential issuer via the first communication interface;
• and
• at the credential issuer, performing said verification using the first proof data and using the credential template token to provide a reissued credential, certifying said set of attributes, to the second tamper-resistant device via the user apparatus.