ECC cofactor: fix check scalar bits #5737
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dgarske
approved these changes
Oct 26, 2022
haydenroche5
suggested changes
Nov 3, 2022
For shared secrets, when a curve has a cofactor, the private key (in range of order) is multiplied by the cofactor before use. If there is a cofactor involved, check bit size of scalar against modulus instead of order.
haydenroche5
approved these changes
Nov 3, 2022
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Description
For shared secrets, when a curve has a cofactor, the private key (in range of order) is multiplied by the cofactor before use.
If there is a cofactor involved, check bit size of scalar against modulus instead of order.
Fixes zd#15017
Testing
Modified test.c to use SECP112R2 instead of SECP112R1.
Checklist