Secure Random Number Generation

Note:

Currently in the beta phase.

Random numbers are primarily used in scenarios such as temporary session key generation and asymmetric encryption key generation. In cryptographic contexts, secure random number generators must possess randomness, unpredictability, and non-repeatability. The random numbers generated by the current system meet the requirements of cryptographically secure pseudorandomness.

Developers can call APIs to achieve the following functionalities:

• Generate secure random numbers of specified lengths for corresponding key generation.
• Specify random seeds to generate sequences of random numbers.

Before development, developers should have a basic understanding of cryptography fundamentals and be familiar with the following key concepts related to random numbers:

• Internal State

  Represents the numerical values in the memory of the random number generator. When the internal state is the same, the random number generator will produce a fixed sequence of random numbers.

• Random Seed

  Data used to initialize the internal state of a pseudorandom number generator. The random number generator uses the seed to generate a sequence of random numbers.

  In the current OpenSSL implementation, the internal state of the random number generator continuously changes. Even if the same seed is set, the generated random number sequence will differ.

Supported Algorithms and Specifications

The random number generation algorithm uses OpenSSL's RAND_priv_bytes interface to generate secure random numbers.

Algorithm	Length (Byte)
CTR_DRBG	[1, INT_MAX]

Development Steps

1. Call createRandom to create a random number instance.

2. (Optional) Set DataBlob data and call setSeed to seed the random number generation pool.

3. Specify the byte length and call generateRandom to generate a secure random number.

   The specified byte length must be within the range of 1 to INT_MAX.

Example

The following demonstrates the synchronous method:

import kit.CryptoArchitectureKit.*
import ohos.hilog.Hilog
import ohos.business_exception.BusinessException

func doRand() {
    let rand = createRandom()
    let len: Int32 = 24 // Generate a 24-byte random number.
    try {
        let randData = rand.generateRandom(len)
        Hilog.info(0,"","rand result: ${randData.data}")
    } catch (e: BusinessException) {
        Hilog.error(0,"","do rand failed, ${e.code}, ${e.message}")
    }
}