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Nomenclator is a complex encryption system consisting of several different simpler encryption systems used together during the encryption. It is one of the main encryption systems used before the twentieth century. In some cases, there are large collections of historical ciphers preserved in archives. Those from a particular time period or geograph...
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Context 1
... will not necessarily solve the whole sub-cipher part but can help in the cryptanalysis. If a special row is present in the homophonic substitution (as in figure 6) and there is sufficient occurrence of these symbols in the ciphertext, we can solve this part as a simple substitution. In Antal and Zajac (2013) and Antal et al. (2021) the authors were able to correctly assign 15 the row of numbers to the homophonic part based on statistical analysis, however, the length of the analyzed text was too short to break the ci-pher. ...
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Citations
... Collecting materials from a particular time period or geographic location can bring insights into the cipher design from a specific time/location. A valuable collection of historical encrypted documents and cipher keys can be found in Austria (Láng, 2020), Germany (Antal and Mírka, 2022), etc. It is thus desirable to investigate and compare various collections from a wide time range and location (Megyesi et al., 2022), because it is essential for understanding how ciphering evolved in the past. ...
... Several publications have already described this cipher system in detail, including its large variety. For more information about this encryption system see (Antal and Mírka, 2022;Megyesi et al., 2022) or other publications published in the proceedings of the His-toCrypt 5 conference. ...
... A nomenclator system can be used with and without separators based on its design. Separators are mostly required to clearly distinguish/split the cipher text units (Antal and Mírka, 2022). In total, 37 encrypted documents contain cipher text with a separator, and 59 are without a separator character. ...
In this article, we present encrypted documents and cipher keys from the 18th and 19th century, related to central-European aristocratic families Amade-Üchtritz, Esterházy, and Pálffy-Daun. In the first part of the article, we present an overview and analysis of the available documents from the archives with examples. We provide a short historical overview of the people related to the analyzed documents to provide a context for the research. In the second part of the article, we focus on the digital processing of these historical manuscripts. We developed new tools based on machine learning that can automate the transcription of encrypted parts of the documents, which contain only digits as cipher text alphabet. Our digit detection and segmentation are based on YOLOv7. YOLOv7 provided good detection precision and was able to cope with problems like noisy paper background and areas where digits collided with the text from the reverse side of the paper.
... The sub-encryption systems (encryption rules) are described by a cipher key, which is very characteristic: the cipher key is mostly drawn on a large paper sheet; the individual sub-encryption systems are mostly graphically separated; the cipher text alphabet is often represented by (combinations of ) letters, numbers, and special symbols/glyphs." [3] A typical ciphertext from our collection is shown in Figure 1 and cipher key in Figure 2. The used cipher symbol set from our collection consists of digits only (including special number modifications). Luckily, the writing style of the encrypted text is clean and the used digits are separated by relatively large spaces. ...
... Many important publications on this subject are presented annually at the International Conference on Historical Cryptology (HistoCrypt). The design and structure of historical cipher keys were investigated in [3,11,14]. These publications are related to the two ongoing projects, namely: ...
This paper deals with historical encrypted manuscripts and introduces an automated method for the detection and transcription of ciphertext symbols for subsequent cryptanalysis. Our database contains documents used in the past by aristocratic families living in the territory of Slovakia. They are encrypted using a nomenclator which is a specific type of substitution cipher. In our case, the nomenclator uses digits as ciphertext symbols. We have proposed a method for the detection, classification, and transcription of handwritten digits from the original documents. Our method is based on Mask R-CNN which is a deep convolutional neural network for instance segmentation. Mask R-CNN was trained on a manually collected database of digit annotations. We employ a specific strategy where the input image is first divided into small blocks. The image blocks are then passed to Mask R-CNN to obtain detections. This way we avoid problems related to the detection of a large number of small dense objects in a high-resolution image. Experiments have shown promising detection performance for all digit types with minimum false detections.
