Merge bitcoin/bitcoin#21817: refactor: Replace &foo[0] with foo.data()

fac30eec42c486ec1bfd696293040a7aa0f04625 refactor: Replace &foo[0] with foo.data() (MarcoFalke)
faece47c4706783e0460ed977390a44630b2d44c refactor: Avoid &foo[0] on C-Style arrays (MarcoFalke)
face9611093377e8502d91f2ff56f9319a56357c refactor: Use only one temporary buffer in CreateObfuscateKey (MarcoFalke)
fa05dddc42770809fdae4d9c35155f8117960019 refactor: Use CPubKey vector constructor where possible (MarcoFalke)
fabb6dfe6e734eadd91448122f2ce8c1612c39a6 script: Replace address-of idiom with vector data() method (Guido Vranken)

Pull request description:

  The main theme of this refactor is to replace `&foo[0]` with `foo.data()`.

  The first commit is taken from #21781 with the rationale:

  * In CSignatureCache::ComputeEntryECDSA, change the way a vector pointer is resolved to prevent invoking undefined behavior if the vector is empty.

  The other commits aim to remove all `&foo[0]`, where `foo` is any kind of byte representation. The rationale:

  * Sometimes alternative code without any raw data pointers is easier to read (refer to the respective commit message for details)
  * If the raw data pointer is needed, `foo.data()` should be preferred, as pointed out in the developer notes. This addresses the instances that have been missed in commit 592404f03f2b734351d734f0c9ca1fdce997321b, and https://github.com/bitcoin/bitcoin/pull/9804

ACKs for top commit:
  laanwj:
    Code review ACK fac30eec42c486ec1bfd696293040a7aa0f04625
  practicalswift:
    cr ACK fac30eec42c486ec1bfd696293040a7aa0f04625: patch looks correct
  promag:
    Code review ACK fac30eec42c486ec1bfd696293040a7aa0f04625.

Tree-SHA512: e7e73146edbc78911a8e8c728b0a1c6b0ed9a88a008e650aa5dbffe72425bd42c76df70199a9cf7e02637448d7593e0eac52fd0f91f59240283e1390ee21bfa5

1 files changed, 3 insertions, 3 deletions

diff --git a/src/wallet/crypter.cpp b/src/wallet/crypter.cpp
index b50f00e7d1..251778e401 100644
--- a/src/wallet/crypter.cpp
+++ b/src/wallet/crypter.cpp
@@ -78,7 +78,7 @@ bool CCrypter::Encrypt(const CKeyingMaterial& vchPlaintext, std::vector<unsigned
     vchCiphertext.resize(vchPlaintext.size() + AES_BLOCKSIZE);
 
     AES256CBCEncrypt enc(vchKey.data(), vchIV.data(), true);
-    size_t nLen = enc.Encrypt(&vchPlaintext[0], vchPlaintext.size(), vchCiphertext.data());
+    size_t nLen = enc.Encrypt(vchPlaintext.data(), vchPlaintext.size(), vchCiphertext.data());
     if(nLen < vchPlaintext.size())
         return false;
     vchCiphertext.resize(nLen);
@@ -97,7 +97,7 @@ bool CCrypter::Decrypt(const std::vector<unsigned char>& vchCiphertext, CKeyingM
     vchPlaintext.resize(nLen);
 
     AES256CBCDecrypt dec(vchKey.data(), vchIV.data(), true);
-    nLen = dec.Decrypt(vchCiphertext.data(), vchCiphertext.size(), &vchPlaintext[0]);
+    nLen = dec.Decrypt(vchCiphertext.data(), vchCiphertext.size(), vchPlaintext.data());
     if(nLen == 0)
         return false;
     vchPlaintext.resize(nLen);
@@ -121,7 +121,7 @@ bool DecryptSecret(const CKeyingMaterial& vMasterKey, const std::vector<unsigned
     memcpy(chIV.data(), &nIV, WALLET_CRYPTO_IV_SIZE);
     if(!cKeyCrypter.SetKey(vMasterKey, chIV))
         return false;
-    return cKeyCrypter.Decrypt(vchCiphertext, *((CKeyingMaterial*)&vchPlaintext));
+    return cKeyCrypter.Decrypt(vchCiphertext, vchPlaintext);
 }
 
 bool DecryptKey(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCryptedSecret, const CPubKey& vchPubKey, CKey& key)