contracts: add curve25519 pk precompile #116
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kostko
approved these changes
Feb 21, 2023
HarryR
reviewed
Mar 24, 2023
| { | ||
| bytes memory scalar = randomBytes(32, pers); | ||
| // Twiddle some bits, as per RFC 7748 §5. | ||
| scalar[0] &= 0xf8; // Make it a multiple of 8 to avoid small subgroup attacks. |
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It is unnecessary to perform a scalar clamp here. The curve25519-dalek library does it when casting bytes32 to field element.
Via:
- https://github.com/oasisprotocol/oasis-sdk/blob/main/runtime-sdk/modules/evm/src/precompile/confidential.rs#L112
- https://github.com/dalek-cryptography/x25519-dalek/blob/main/src/x25519.rs#L253
- https://github.com/dalek-cryptography/curve25519-dalek/blob/a63e14f4ded078d6bf262ba0b3f47026bdd7f7c0/src/scalar.rs#L300
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Nice catch, thanks! Can you open up a PR with the proposed fix (removing the scalar clamp)?
HarryR
reviewed
Mar 27, 2023
| @@ -14,12 +14,17 @@ library Sapphire { | |||
| 0x0100000000000000000000000000000000000003; | |||
| address private constant DECRYPT = | |||
| 0x0100000000000000000000000000000000000004; | |||
| address private constant GENERATE_KEYPAIR = | |||
| address private constant GENERAGE_SIGNING_KEYPAIR = | |||
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Indeed! Can you open up a PR with the fix? Thanks a lot!
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