From 221f499041a45d1246ecacfd3e479aaaca7ac83a Mon Sep 17 00:00:00 2001
From: Sam Kim <skim13@cs.stanford.edu>
Date: Wed, 20 Oct 2021 13:06:22 -0400
Subject: [PATCH] derive ElGamal keypair from the secret component of keypair

---
 zk-token-sdk/Cargo.toml                |  1 -
 zk-token-sdk/src/encryption/aes.rs     |  6 +++---
 zk-token-sdk/src/encryption/elgamal.rs | 15 +++++++--------
 3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/zk-token-sdk/Cargo.toml b/zk-token-sdk/Cargo.toml
index d1171dcd27..35baa54c1a 100644
--- a/zk-token-sdk/Cargo.toml
+++ b/zk-token-sdk/Cargo.toml
@@ -22,7 +22,6 @@ bincode = "1"
 byteorder = "1"
 cipher = "0.3"
 curve25519-dalek = { version = "3.2.0", features = ["serde"]}
-ed25519-dalek = "=1.0.1"
 getrandom = { version = "0.1", features = ["dummy"] }
 merlin = "2"
 rand = "0.7"
diff --git a/zk-token-sdk/src/encryption/aes.rs b/zk-token-sdk/src/encryption/aes.rs
index fd5e1801ad..12c285dad1 100644
--- a/zk-token-sdk/src/encryption/aes.rs
+++ b/zk-token-sdk/src/encryption/aes.rs
@@ -6,8 +6,8 @@ use {
 };
 use {
     arrayref::{array_ref, array_refs},
-    ed25519_dalek::SecretKey as SigningKey,
     solana_sdk::pubkey::Pubkey,
+    solana_sdk::signature::Keypair as SigningKeypair,
     std::convert::TryInto,
     zeroize::Zeroize,
 };
@@ -54,9 +54,9 @@ impl Aes {
 #[derive(Debug, Zeroize)]
 pub struct AesKey([u8; 16]);
 impl AesKey {
-    pub fn new(signing_key: &SigningKey, address: &Pubkey) -> Self {
+    pub fn new(signing_keypair: &SigningKeypair, address: &Pubkey) -> Self {
         let mut hashable = [0_u8; 64];
-        hashable[..32].copy_from_slice(&signing_key.to_bytes());
+        hashable[..32].copy_from_slice(&signing_keypair.secret().to_bytes());
         hashable[32..].copy_from_slice(&address.to_bytes());
 
         let mut hasher = Sha3_256::new();
diff --git a/zk-token-sdk/src/encryption/elgamal.rs b/zk-token-sdk/src/encryption/elgamal.rs
index 6b69b572ae..b42745a61c 100644
--- a/zk-token-sdk/src/encryption/elgamal.rs
+++ b/zk-token-sdk/src/encryption/elgamal.rs
@@ -11,9 +11,9 @@ use {
         ristretto::{CompressedRistretto, RistrettoPoint},
         scalar::Scalar,
     },
-    ed25519_dalek::Keypair as SigningKeyPair,
     serde::{Deserialize, Serialize},
     solana_sdk::pubkey::Pubkey,
+    solana_sdk::signature::Keypair as SigningKeypair,
     std::collections::HashMap,
     std::convert::TryInto,
     subtle::{Choice, ConstantTimeEq},
@@ -136,8 +136,8 @@ impl ElGamalKeypair {
     /// address.
     #[cfg(not(target_arch = "bpf"))]
     #[allow(non_snake_case)]
-    pub fn new(signing_key_pair: &SigningKeyPair, address: &Pubkey) -> Self {
-        let secret = ElGamalSecretKey::new(signing_key_pair, address);
+    pub fn new(signing_keypair: &SigningKeypair, address: &Pubkey) -> Self {
+        let secret = ElGamalSecretKey::new(signing_keypair, address);
         let public = ElGamalPubkey::new(&secret);
 
         Self { public, secret }
@@ -292,11 +292,10 @@ impl fmt::Display for ElGamalPubkey {
 #[zeroize(drop)]
 pub struct ElGamalSecretKey(Scalar);
 impl ElGamalSecretKey {
-    pub fn new(signing_key_pair: &SigningKeyPair, address: &Pubkey) -> Self {
-        let mut hashable = [0_u8; 96];
-        hashable[..32].copy_from_slice(&signing_key_pair.secret.to_bytes());
-        hashable[32..64].copy_from_slice(&signing_key_pair.public.to_bytes());
-        hashable[64..].copy_from_slice(&address.to_bytes());
+    pub fn new(signing_keypair: &SigningKeypair, address: &Pubkey) -> Self {
+        let mut hashable = [0_u8; 64];
+        hashable[..32].copy_from_slice(&signing_keypair.secret().to_bytes());
+        hashable[32..].copy_from_slice(&address.to_bytes());
         ElGamalSecretKey(Scalar::hash_from_bytes::<Sha3_512>(&hashable))
     }