| CPC H04L 9/085 (2013.01) [H04L 9/3073 (2013.01); H04L 9/3249 (2013.01); H04L 9/3268 (2013.01)] | 20 Claims |

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1. A method, comprising:
(a) generating a key pair, the key pair including a data signing key and a signature verification public key;
(b) transforming the data signing key into a first subkey and a second subkey;
(c) encrypting the first subkey according to a secret key of an online data signing system (ODSS);
(d) providing the signature verification public key, the encrypted first subkey, and the second subkey to a client device;
(e) accepting a request to sign data, the request comprising:
(1) a representation of the data to be signed; and
(2) the encrypted first subkey;
(f) generating a partially computed signature of the data according to the representation of the data and the encrypted first subkey; and
(g) providing the partially computed signature of the data to the client device.
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