baobiao / TimedAES

Attempt to create an AES Encryption library that limits the decryption of secret to be during the Time specified in the encryption process.

Timed AES Encryption Library

Attempt to create an AES Encryption library that limits the decryption of secret to be during the Time specified in the encryption process.

Version 1 Design

We propose to replace the least significant 2 bytes in the nonce with the allowByUOM and allowByValue respectively, keeping the first 10 bytes random.

0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff 0xff [__allowByUOM__] [__allowByValue__]

The modified nonce is used to encrypt the plain text string. During decryption, the least significant 2 byes in the nonce is compared against the current local date time. Runtime exception is thrown if current date time does not match the values specified during encryption.

Note - This design assumes assumes that the runtime system date time is not modified and in-sync with a Time Server on the network.

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01 Encryption Method

Encryption.encryptWithAES(
    String plainText, 
    Path secretKeyFile, 
    Encryption.AllowByUOM allowByUOM, 
    int allowByValue)

• plainText - String to be encrypted.
• secretKeyFile - Path to AES secret key file.
• allowByUOM - Refer to AllowByUOM enumeration.
• allowByValue - Refer to AllowByUOM enumeration.

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02 Decryption Method

Decryption.decryptWithAES(
    String encryptedString, 
    Path secretKeyFile)

• encryptedString - String to be decrypted.
• secretKeyFile - Path to AES secret key file.

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03 Generate Secret Key Method

GenerateKey.generateAesKey(
    Path keyFile, 
    int keyLength)

• keyFile - Path to AES secret key file.
• keyLength - Length of AES secret key. By specifications must be 128, 192, or 256.

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04 Encryption Enumeration

Encryption enumeration that limits the decryption to be permissible only during the following specified periods:

• MONTH (0 to 11 inclusive) - February is 1.
• DAYOFMONTH (0 to 30 inclusive) - First day of month is 0.
• DAYOFWEEK (0 to 6 inclusive) - Monday is 0.
• HOUR (0 to 23 inclusive) - Midnight is 0.

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