[zk-sdk-wasm-js] Add functions to create ElGamal ciphertexts from a pre-specified Pedersen opening #196
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grod220
reviewed
Jan 5, 2026
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| // Check if the commitment matches what the zk-sdk would create. | ||
| let expected_inner = pedersen::Pedersen::with(amount, &opening.inner); | ||
| assert_eq!(commitment.inner, expected_inner); | ||
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Not a relevant assertion anymore?
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Yeah I tried to remove instances of functions from the zk-sdk and I thought this was a pretty minor assertion, so I removed it. But I don't think it hurts to keep it, so added it back in!
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| #[wasm_bindgen(js_name = "encryptWith")] | ||
| pub fn encrypt_with( | ||
| first_pubkey: &ElGamalPubkey, | ||
| second_pubkey: &ElGamalPubkey, | ||
| amount: u64, | ||
| opening: &PedersenOpening, | ||
| ) -> Self { | ||
| let inner = grouped_elgamal::GroupedElGamal::encrypt_with( | ||
| [&first_pubkey.inner, &second_pubkey.inner], | ||
| amount, | ||
| &opening.inner, | ||
| ); | ||
| Self { inner } | ||
| } |
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Could we get a test somewhere for this? Maybe something like:
#[wasm_bindgen_test]
fn test_encrypt_with_decrypts_correctly() {
let keypair = ElGamalKeypair::new_rand();
let amount = 42u64;
let opening = PedersenOpening::new_rand();
let ciphertext = keypair.pubkey().encrypt_with(amount, &opening);
let decrypted = keypair.decrypt_u32(&ciphertext);
assert_eq!(decrypted, Some(42));
}
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Yep good idea. Added!
grod220
approved these changes
Jan 6, 2026
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Problem
Currently, it is not possible to generate ciphertext validity proofs and equality proofs purely using JS/TS because there is no way to generate an ElGamal ciphertext using a pre-specified Pedersen opening. This function exists in the
zk-sdk, but there is no wrapper function inside thezk-sdk-wasm-jscrate.Summary of Changes
Added the
encrypt_withfunction to thezk-sdk-wasm-jscrate.The reason why I missed this originally was that some of the unit tests are using functions from the
zk-sdkrather than using functions from thezk-sdk-wasm-js. So I also updated some unit tests to use functions directly fromzk-sdk-wasm-js.