Systems and methods for threshold cryptography for cloud-based software-implemented hardware security modules
Disclosed herein are systems and methods for threshold cryptography for cloud-based software-implemented hardware security modules. In an embodiment, an encryption system collects at least a decryption-threshold number of private-key shares from a secure store, where the private-key shares correspond to a public key generated in a first secure enclave as part of a secret key set, which also includes a first plural quantity of the private-key shares. The encryption system obtains an ephemeral-hardware-security-module-(eHSM)-encryption key by decrypting the collected private-key shares. The encryption system initializes, in a second secure enclave, a second instance of a first eHSM. The initialized second instance of the first eHSM is encrypted with the obtained eHSM-encryption key.
1 . A method performed by an encryption system executing instructions on at least one hardware processor, the method comprising:
collecting at least a decryption-threshold number of private-key shares from a secure store, the private-key shares corresponding to a public key generated in a first secure enclave as part of a secret key set, the secret key set further comprising a first plural quantity of the private-key shares;
obtaining an ephemeral-hardware-security-module-(eHSM)-encryption key by decrypting the collected private-key shares; and
initializing, in a second secure enclave, a second instance of a first soft eHSM, the initialized second instance of the first soft eHISM being encrypted with the obtained eHSM-encryption key.
2 . The method of claim 1 , wherein the decryption-threshold number is greater than half of the first plural quantity.
3 . The method of claim 1 , wherein the secure store is external to a secure computing platform on which the second secure enclave is executing.
4 . The method of claim 1 , wherein:
the private-key shares are stored in the secure store such that each private-key share is further encrypted in the secure store with a different respective storage-encryption key; and
the respective storage-encryption keys are managed by a key-management service (KMS).
5 . The method of claim 4 , wherein the KMS comprises a multiregional KMS that stores the encrypted private-key shares across multiple different geographic regions of the KMS.
6 . The method of claim 4 , wherein the KMS implements key rotation with respect to the storage-encryption keys.
7 . The method of claim 1 , further comprising generating the secret key set in the first secure enclave.
8 . The method of claim 1 , further comprising generating the eHSM-encryption key in the first secure enclave.
9 . The method of claim 8 , further comprising:
encrypting, in the first secure enclave, the eHSM-encryption key with the public key; and
transmitting the encrypted eHSM-encryption key to the secure store for storage therein.
10 . The method of claim 8 , further comprising initializing, in the first secure enclave, a first instance of the first soft eHSM, the initialized first instance of the first soft eHSM being encrypted with the eHSM-encryption key.
11 . The method of claim 1 , wherein decrypting the collected private-key shares comprises instantiating a respective secure enclave for decrypting each of the collected private-key shares.
12 . The method of claim 1 , further comprising, prior to the collecting of the at least the decryption-threshold number of the private-key shares from the secure store:
utilizing a pseudorandom-selection algorithm to select the at least the decryption-threshold number of the private-key shares from among the first plural quantity of the private-key shares.
13 . An encryption system comprising:
at least one hardware processor; and
one or more non-transitory computer readable storage media containing instructions that, when executed by the at least one hardware processor, cause the at least one hardware processor to perform operations comprising:
collecting at least a decryption-threshold number of private-key shares from a secure store, the private-key shares corresponding to a public key generated in a first secure enclave as part of a secret key set, the secret key set further comprising a first plural quantity of the private-key shares;
obtaining an ephemeral-hardware-security-module-(eHSM)-encryption key by decrypting the collected private-key shares; and
initializing, in a second secure enclave, a second instance of a first soft eHSM, the initialized second instance of the first soft eHSM being encrypted with the obtained eHSM-encryption key.
14 . The encryption system of claim 13 , wherein the decryption-threshold number is greater than half of the first plural quantity.
15 . The encryption system of claim 13 , wherein the secure store is external to a secure computing platform on which the second secure enclave is executing.
16 . The encryption system of claim 13 , wherein:
the private-key shares are stored in the secure store such that each private-key share is further encrypted in the secure store with a different respective storage-encryption key; and
the respective storage-encryption keys are managed by a key-management service (KMS).
17 . The encryption system of claim 16 , wherein the KMS comprises a multiregional KMS that stores the encrypted private-key shares across multiple different geographic regions of the KMS.
18 . The encryption system of claim 16 , wherein the KMS implements key rotation with respect to the storage-encryption keys.
19 . The encryption system of claim 13 , the operations further comprising generating the secret key set in the first secure enclave.
20 . The encryption system of claim 13 , the operations further comprising generating the eHSM-encryption key in the first secure enclave.
21 . The encryption system of claim 20 , the operations further comprising:
encrypting, in the first secure enclave, the eHSM-encryption key with the public key; and
transmitting the encrypted eHSM-encryption key to the secure store for storage therein.
22 . The encryption system of claim 20 , the operations further comprising initializing, in the first secure enclave, a first instance of the first soft eHSM, the initialized first instance of the first soft eHSM being encrypted with the eHSM-encryption key.
23 . The encryption system of claim 13 , wherein decrypting the collected private-key shares comprises instantiating a respective secure enclave for decrypting each of the collected private-key shares.
24 . The encryption system of claim 13 , the operations further comprising, prior to the collecting of the at least the decryption-threshold number of the private-key shares from the secure store:
utilizing a pseudorandom-selection algorithm to select the at least the decryption-threshold number of the private-key shares from among the first plural quantity of the private-key shares.
25 . One or more non-transitory computer readable storage media containing instructions that, when executed by at least one hardware processor, cause the at least one hardware processor to perform operations comprising:
collecting at least a decryption-threshold number of private-key shares from a secure store, the private-key shares corresponding to a public key generated in a first secure enclave as part of a secret key set, the secret key set further comprising a first plural quantity of the private-key shares;
obtaining an ephemeral-hardware-security-module-(eHSM)-encryption key by decrypting the collected private-key shares; and
initializing, in a second secure enclave, a second instance of a first soft eHSM, the initialized second instance of the first soft eHSM being encrypted with the obtained eHSM-encryption key.