A Memorial in Line Segment Cipher from Peru (1604)

In the Spanish archives, there is a memorial dating from 1604 entirely written in a strange-looking cipher consisting of line segments directed in different directions.

A contemporary key ('contracifra') discovered by Luis Valle de la Cerda was found in France.

As it turned out, not only the directions of the line segments but also the position in the square is relevant. Three positions are distinguished among upper vertical strokes for b, c, and d. The same applies to lower vertical strokes and left and right horizontal strokes. Two positions are distinguished for diagonal strokes at each corner (e.g., for a and t). For accurate enciphering and deciphering, it must have been necessary to apply a grid under the sheet.

The four points serve for registration of the grid with the sheet. Special symbols are assigned for ñ, ll, rr, and mgd (Magestad).


The author of the memorial was José de Orozco y Gamarra in Peru. He intended to provide the King with important information. He wrote the memorial in cipher and trusted it with his son, Bartolomé Inga de Orozco, who embarked in mid-1604 from Callao.

In Spain, the memorial was read to the Junta de Minas according to the instructions of the bearer. To make sure of the accuracy of the content, the Council of the Indias gave the letter to Luis Valle de la Cerda, who discovered the key. His decipher perfectly matched the translation he refused to receive.

The key discovered by de la Cerda is followed by the plaintext of the memorial. Orozco y Gamarra thought he was conveying secret techniques for increasing the turnout of silver mines of Peru but its content reveals the backwardness of metallurgy in south America at the time (Helmer p.430).

Another Line Segment Cipher

See also another article for another line segment cipher by the Earl of Glamorgan (1645).


Guillermo Lohmann Villena (1954), 'Cifras y Claves Indianas,' Anuario de Estudios Americanos, XI, p.285

Marie Helmer (1960), 'La clef du mystere (papiers chiffres relatifs aux mines d'argent du Perou),' Bulletin Hispanique, Tome 62, No. 4, p.428 (PDF)

©2011 S.Tomokiyo
First posted on 1 May 2011. Last modified on 29 March 2012.
Articles on Historical Cryptography
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