A computer-implemented method for managing a cryptographic key to create an account in a blockchain system, the method comprising: receiving a request for a signature on transaction data; allocating a key manager corresponding to the request, comprising: determining whether the request includes internal testing account information; in response to a determination that the request includes the internal testing account information, allocating a first key manager that is to generate the cryptographic key; in response to a determination that the request does not include the internal testing account information, determining whether the request includes bank account information; and in response to a determination that the request includes the bank account information, allocating a second key manager that is to obtain the signature on the transaction data and the cryptographic key from a bank; and obtaining, by the allocated key manager, the signature on the transaction data and the cryptographic key, wherein the cryptographic key is a public key and the signature on the transaction data is obtained based on a private key corresponding to the public key, wherein obtaining, by the allocated key manager, the signature on the transaction data and the cryptographic key comprises: generating, by the allocated key manager, a mock cryptographic key as the cryptographic key and obtaining, by the allocated key manager, a mock signature on the transaction data as the signature on the transaction data when the allocated key manager is the first key manager, and obtaining, by the allocated key manager, the signature on the transaction data and the cryptographic key from the bank when the allocated key manager is the second key manager. receiving a request for a signature on transaction data; allocating a key manager corresponding to the request, comprising: determining whether the request includes internal testing account information; in response to a determination that the request includes the internal testing account information, allocating a first key manager that is to generate the cryptographic key; in response to a determination that the request does not include the internal testing account information, determining whether the request includes bank account information; and in response to a determination that the request includes the bank account information, allocating a second key manager that is to obtain the signature on the transaction data and the cryptographic key from a bank; and determining whether the request includes internal testing account information; in response to a determination that the request includes the internal testing account information, allocating a first key manager that is to generate the cryptographic key; in response to a determination that the request does not include the internal testing account information, determining whether the request includes bank account information; and in response to a determination that the request includes the bank account information, allocating a second key manager that is to obtain the signature on the transaction data and the cryptographic key from a bank; and obtaining, by the allocated key manager, the signature on the transaction data and the cryptographic key, wherein the cryptographic key is a public key and the signature on the transaction data is obtained based on a private key corresponding to the public key, wherein obtaining, by the allocated key manager, the signature on the transaction data and the cryptographic key comprises: generating, by the allocated key manager, a mock cryptographic key as the cryptographic key and obtaining, by the allocated key manager, a mock signature on the transaction data as the signature on the transaction data when the allocated key manager is the first key manager, and obtaining, by the allocated key manager, the signature on the transaction data and the cryptographic key from the bank when the allocated key manager is the second key manager. generating, by the allocated key manager, a mock cryptographic key as the cryptographic key and obtaining, by the allocated key manager, a mock signature on the transaction data as the signature on the transaction data when the allocated key manager is the first key manager, and obtaining, by the allocated key manager, the signature on the transaction data and the cryptographic key from the bank when the allocated key manager is the second key manager.