Encrypted data recovery method using split storage key and system thereof

摘要

When a secret is encrypted and stored, it is necessary to provide for a countermeasure for lost key (key recovery system). In the present invention, a key recovery system for an enveloped data format in which a common key is used to encrypt a plaintext (secret) and a user's public key is used to encrypt the common key and attached to an encrypted text is provided. In the present invention, only the common key is decrypted (203, 221) to recover the secret (204) without reconstruction of split secret keys kept in a plurality of key storage apparatuses.