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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