Cipher runes, orcryptic runes, are thecryptographical replacement of the letters of therunic alphabet.
The knowledge of cipher runes was best preserved inIceland, and during the 17th–18th centuries, Icelandic scholars produced several treatises on the subject. The most notable of these is the manuscriptRunologia byJón Ólafsson (1705–1779), which he wrote inCopenhagen (1732–1752). It thoroughly treats numerous cipher runes and runic ciphers, and it is now preserved in theArnamagnæan Institute in Copenhagen.[1]
Jón Ólafsson's treatise presents theYounger Futhark in the Viking Age order, which means that them-rune precedes thel-rune. This small detail was of paramount importance for the interpretation of Viking Age cipher runes because in the 13th century the two runes had changed places through the influence of theLatin alphabet wherel precedesm. Since the medievalrunic calendar used the post-13th-century order, the early runologists of the 17th–18th centuries believed that the l-m order was the original one, and the order of the runes is of vital importance for the interpretation of cipher runes.[1]
In the runic alphabet, the runes have their special order and are divided into groups. In theYounger Futhark, which has 16 letters, they are divided into three groups. The Icelandic tradition calls the first group (f,u,þ,ã,r andk) "Freyr'sætt", the second group (h,n,i,a ands) "Hagal'sætt" and the third group (t,b,m,l andʀ) "Tyr'sætt". In order to make the inscription even harder to decipher, Freyr'sætt and Tyr'sætt change places so that group one is group three and vice versa. However, in several cases the ætts are counted in their correct order, and not backwards.[2][better source needed] There are numerous forms of cipher runes, but they are all based on the principle of giving the number of theætt and the number of the rune within theætt.[3]
Thetent runes are based on strokes added to the four arms of an X shape: Each X represents two runes and is read clockwise, starting with the top left arm. The strokes on the first arm representing theætt (row of eight runes: (1)fuþarkgw, (2)hnijæpzs, (3)tbemlŋod), the strokes on the second arm denote the order within thatætt.
Thebranch runes are similar, the strokes being attached to a vertical stem and branching upwards. Strokes on the left indicate theætt, and strokes on the right the order within theætt.
There are variants of these two schemes, such as inverting the numbers (counting backwards theætts, and the runes within theætts).Tree runes andhook runes are like branch runes, with the strokes pointing downward diagonally and curving downward, respectively. These may be mixed: in the phraseek vitki at left,ek is written in straightforward branch runes, butvitki is written with theætts as hooks and the order as branches.
There are severalrunestones using such devices of obscuring the inscription, especially found inOrkney.
A comparable system of letter modification is that of theOgham "scales" recorded in theOgam Tract.