The utility of true random number generators (TRNGs) is not only restricted to session key generation, nonce generation, OTP generation etc. in cryptography. In the proposed work, two ring oscillator (RO) based TRNG structures adopting identical and non-identical ring of inverters have alone been employed for confusion (scrambling) and diffusion (intensity variation) processes for encrypting the greyscale and RGB images. Cyclone IVE EP4CE115F29C7 FPGA was utilised to generate a couple of random synthetic images using the two RO architectures which took a maximum of 520 combinational units and 543 logic registers. The suggested scheme of image encryption was tested on 100 test greyscale images of size 256 × 256. This non-chaos influenced image ciphering has resulted in an approximate average entropy of 7.99 and near-zero correlation figures for the greyscale & RGB cipher images. The attack resistance capability was checked by performing various occlusion and noise attacks on encrypted images.

中文翻译：

---

环形振荡器令人困惑–扩散剂：完整的TRNG推动了图像安全性

真正的随机数生成器（TRNG）的用途不仅限于加密中的会话密钥生成，随机数生成，OTP生成等。在提出的工作中，仅采用两个采用相同和不同的反相器环的基于环形振荡器（RO）的TRNG结构来进行混淆（加扰）和扩散（强度变化）过程，以对灰度和RGB图像进行加密。Cyclone IVE EP4CE115F29C7 FPGA使用两种RO架构来生成一对随机合成图像，该架构最多占用520个组合单元和543个逻辑寄存器。在100个大小为256×256的测试灰度图像上测试了建议的图像加密方案。这种不受混沌影响的图像加密方法得出的平均平均熵约为7。灰度和RGB密码图像的相关系数为99，接近零。通过对加密图像执行各种遮挡和噪声攻击来检查抗攻击能力。