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RIPEMD160 - how were these constants created?

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I have been through several sources and papers, but I can't seem to find how these rotation constants were created. Are these constants arbitrary, or were there chosen by some kind of permutation? I can't really find any source.

The order of the left rotates on the left hand side are:

{{11, 14, 15, 12, 5, 8, 7, 9, 11, 13, 14, 15, 6, 7, 9, 8}, //Round 1 
{7, 6, 8, 13, 11, 9, 7, 15, 7, 12, 15, 9, 11, 7, 13, 12}, //Round 2
{11, 13, 6, 7, 14, 9, 13, 15, 14, 8, 13, 6, 5, 12, 7, 5}, //Round 3
{11, 12, 14, 15, 14, 15, 9, 8, 9, 14, 5, 6, 8, 6, 5, 12}, //Round 4
{9, 15, 5, 11, 6, 8, 13, 12, 5, 12, 13, 14, 11, 8, 5, 6}} //Round 5

The order of the left rotates on the right hand side are:

{{8, 9, 9, 11, 13, 15, 15, 5, 7, 7, 8, 11, 14, 14, 12, 6}, //Round 1
{9, 13, 15, 7, 12, 8, 9, 11, 7, 7, 12, 7, 6, 15, 13, 11}, //Round 2
{9, 7, 15, 11, 8, 6, 6, 14, 12, 13, 5, 14, 13, 13, 7, 5}, //Round 3
{15, 5, 8, 11, 14, 14, 6, 14, 6, 9, 12, 9, 12, 5, 15, 8}, //Round 4
{8, 5, 12, 9, 12, 5, 14, 6, 8, 13, 6, 5, 15, 13, 11, 11}}; //Round 5
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