Revert SaplingNoteEncryption::new() API to take rng instead of esk

zcash_client_backend/src/welding_rig.rs

@@ -262,13 +262,12 @@ mod tests {
             value: value.into(),
             rseed,
         };
-        let esk = note.generate_or_derive_esk(&mut rng);
         let encryptor = SaplingNoteEncryption::new(
             extfvk.fvk.ovk,
             note.clone(),
             to.clone(),
             Memo::default(),
-            esk,
+            &mut rng,
         );
         let cmu = note.cm(&JUBJUB).to_repr().as_ref().to_owned();
         let mut epk = vec![];

zcash_client_sqlite/src/lib.rs

@@ -133,13 +133,12 @@ mod tests {
             value: value.into(),
             rseed,
         };
-        let esk = note.generate_or_derive_esk(&mut rng);
         let encryptor = SaplingNoteEncryption::new(
             extfvk.fvk.ovk,
             note.clone(),
             to.clone(),
             Memo::default(),
-            esk,
+            &mut rng,
         );
         let cmu = note.cm(&JUBJUB).to_repr().as_ref().to_vec();
         let mut epk = vec![];
@@ -195,9 +194,13 @@ mod tests {
                 value: value.into(),
                 rseed,
             };
-            let esk = note.generate_or_derive_esk(&mut rng);
-            let encryptor =
-                SaplingNoteEncryption::new(extfvk.fvk.ovk, note.clone(), to, Memo::default(), esk);
+            let encryptor = SaplingNoteEncryption::new(
+                extfvk.fvk.ovk,
+                note.clone(),
+                to,
+                Memo::default(),
+                &mut rng,
+            );
             let cmu = note.cm(&JUBJUB).to_repr().as_ref().to_vec();
             let mut epk = vec![];
             encryptor.epk().write(&mut epk).unwrap();
@@ -220,13 +223,12 @@ mod tests {
                 value: (in_value - value).into(),
                 rseed,
             };
-            let esk = note.generate_or_derive_esk(&mut rng);
             let encryptor = SaplingNoteEncryption::new(
                 extfvk.fvk.ovk,
                 note.clone(),
                 change_addr,
                 Memo::default(),
-                esk,
+                &mut rng,
             );
             let cmu = note.cm(&JUBJUB).to_repr().as_ref().to_vec();
             let mut epk = vec![];

zcash_primitives/src/note_encryption.rs

@@ -15,6 +15,7 @@ use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
 use crypto_api_chachapoly::{ChaCha20Ietf, ChachaPolyIetf};
 use ff::PrimeField;
 use pairing::bls12_381::{Bls12, Fr};
+use rand_core::{CryptoRng, RngCore};
 use std::convert::TryInto;
 use std::fmt;
 use std::str;
@@ -236,8 +237,7 @@ fn prf_ock(
 /// let note = to.create_note(value, Rseed::BeforeZip212(rcm), &JUBJUB).unwrap();
 /// let cmu = note.cm(&JUBJUB);
 ///
-/// let esk = note.generate_or_derive_esk(&mut rng);
-/// let enc = SaplingNoteEncryption::new(ovk, note, to, Memo::default(), esk);
+/// let enc = SaplingNoteEncryption::new(ovk, note, to, Memo::default(), &mut rng);
 /// let encCiphertext = enc.encrypt_note_plaintext();
 /// let outCiphertext = enc.encrypt_outgoing_plaintext(&cv.cm(&JUBJUB).into(), &cmu);
 /// ```
@@ -252,13 +252,14 @@ pub struct SaplingNoteEncryption {
 
 impl SaplingNoteEncryption {
     /// Creates a new encryption context for the given note.
-    pub fn new(
+    pub fn new<R: RngCore + CryptoRng>(
         ovk: OutgoingViewingKey,
         note: Note<Bls12>,
         to: PaymentAddress<Bls12>,
         memo: Memo,
-        esk: Fs,
+        rng: &mut R,
     ) -> SaplingNoteEncryption {
+        let esk = note.generate_or_derive_esk(rng);
         let epk = note.g_d.mul(esk, &JUBJUB);
 
         SaplingNoteEncryption {
@@ -809,8 +810,7 @@ mod tests {
         let cmu = note.cm(&JUBJUB);
 
         let ovk = OutgoingViewingKey([0; 32]);
-        let esk = note.generate_or_derive_esk(&mut rng);
-        let ne = SaplingNoteEncryption::new(ovk, note, pa, Memo([0; 512]), esk);
+        let ne = SaplingNoteEncryption::new(ovk, note, pa, Memo([0; 512]), &mut rng);
         let epk = ne.epk();
         let enc_ciphertext = ne.encrypt_note_plaintext();
         let out_ciphertext = ne.encrypt_outgoing_plaintext(&cv, &cmu);
@@ -1705,9 +1705,7 @@ mod tests {
             // Test encryption
             //
 
-            let _esk = note.generate_or_derive_esk(&mut OsRng);
-
-            let mut ne = SaplingNoteEncryption::new(ovk, note, to, Memo(tv.memo), _esk);
+            let mut ne = SaplingNoteEncryption::new(ovk, note, to, Memo(tv.memo), &mut OsRng);
             // Swap in the ephemeral keypair from the test vectors
             ne.esk = esk;
             ne.epk = epk;

zcash_primitives/src/transaction/builder.rs

@@ -133,7 +133,7 @@ impl SaplingOutput {
             self.note.clone(),
             self.to.clone(),
             self.memo,
-            self.note.generate_or_derive_esk(rng),
+            rng,
         );
 
         let (zkproof, cv) = prover.output_proof(