Consider the Gaussian wiretap channel, where a transmitter wishes to send a confidential message to a legitimate receiver in the presence of an eavesdropper. It is well known that if the eavesdropper experiences less channel noise than the legitimate receiver, then it is impossible for the transmitter to achieve positive secrecy rates. A known solution to this issue consists in involving a second transmitter, referred to as a helper, to help the first transmitter to achieve security. While such a solution has been studied for the asymptotic blocklength regime and via non-constructive coding schemes, in this paper, for the first time, we design explicit and short blocklength codes using deep learning and cryptographic tools to demonstrate the benefit and practicality of cooperation between two transmitters over the wiretap channel. Specifically, our proposed codes show strict improvement in terms of information leakage compared to existing codes that do not consider a helper. Our code design approach relies on a reliability layer, implemented with an autoencoder architecture based on the successive interference cancellation method, and a security layer implemented with universal hash functions. We also propose an alternative autoencoder architecture that significantly reduces training time by allowing the decoders to independently estimate messages without successively canceling interference by the receiver during training. Additionally, we show that our code design is also applicable to the multiple access wiretap channel with helpers, where two transmitters send confidential messages to the legitimate receiver.

翻译：考虑Gaussian窃听信道，其中发送方希望在窃听者存在的情况下向合法接收方发送机密消息。众所周知，若窃听者经历的信道噪声小于合法接收方，则发送方无法实现正的保密速率。针对该问题的已知解决方案涉及引入第二个发送方（称为辅助方）以协助第一个发送方实现安全性。尽管此类解决方案已在渐近码长机制下通过非构造性编码方案进行研究，但本文首次利用深度学习和密码学工具设计显式且短码长的编码方案，以论证两个发送方在窃听信道上协作的益处与实用性。具体而言，与现有未考虑辅助方的编码相比，我们提出的编码在信息泄露方面显示出严格改进。我们的编码设计方法依赖于可靠性层（采用基于连续干扰消除方法的自编码器架构实现）和安全性层（采用通用哈希函数实现）。我们还提出了一种替代的自编码器架构，通过允许解码器在训练期间独立估计消息而无需接收方连续消除干扰，显著减少了训练时间。此外，我们证明了我们的编码设计同样适用于带辅助方的多址窃听信道，其中两个发送方向合法接收方发送机密消息。