crypto: add some more byte-orientated versions.

This change adds byte (as opposed to std::string) based functions to
save callers some copies and casts.

Change-Id: Ib3306c6abf14c8ff849009e1752284bc693da44a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1776793
Commit-Queue: Adam Langley <agl@chromium.org>
Reviewed-by: David Benjamin <davidben@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692159}

crypto/hkdf.cc

@@ -31,4 +31,17 @@ std::string HkdfSha256(base::StringPiece secret,
   return key;
 }
 
+std::vector<uint8_t> HkdfSha256(base::span<const uint8_t> secret,
+                                base::span<const uint8_t> salt,
+                                base::span<const uint8_t> info,
+                                size_t derived_key_size) {
+  std::vector<uint8_t> ret;
+  ret.resize(derived_key_size);
+  int result =
+      ::HKDF(ret.data(), derived_key_size, EVP_sha256(), secret.data(),
+             secret.size(), salt.data(), salt.size(), info.data(), info.size());
+  DCHECK(result);
+  return ret;
+}
+
 }  // namespace crypto

crypto/hkdf.h

@@ -9,6 +9,7 @@
 
 #include <string>
 
+#include "base/containers/span.h"
 #include "base/strings/string_piece.h"
 #include "crypto/crypto_export.h"
 
@@ -20,6 +21,12 @@ std::string HkdfSha256(base::StringPiece secret,
                        base::StringPiece info,
                        size_t derived_key_size);
 
+CRYPTO_EXPORT
+std::vector<uint8_t> HkdfSha256(base::span<const uint8_t> secret,
+                                base::span<const uint8_t> salt,
+                                base::span<const uint8_t> info,
+                                size_t derived_key_size);
+
 }  // namespace crypto
 
 #endif  // CRYPTO_HKDF_H_

crypto/sha2.cc

@@ -10,9 +10,16 @@
 
 #include "base/stl_util.h"
 #include "crypto/secure_hash.h"
+#include "third_party/boringssl/src/include/openssl/sha.h"
 
 namespace crypto {
 
+std::array<uint8_t, kSHA256Length> SHA256Hash(base::span<const uint8_t> input) {
+  std::array<uint8_t, kSHA256Length> digest;
+  ::SHA256(input.data(), input.size(), digest.data());
+  return digest;
+}
+
 void SHA256HashString(base::StringPiece str, void* output, size_t len) {
   std::unique_ptr<SecureHash> ctx(SecureHash::Create(SecureHash::SHA256));
   ctx->Update(str.data(), str.length());

crypto/sha2.h

@@ -7,8 +7,10 @@
 
 #include <stddef.h>
 
+#include <array>
 #include <string>
 
+#include "base/containers/span.h"
 #include "base/strings/string_piece.h"
 #include "crypto/crypto_export.h"
 
@@ -20,6 +22,14 @@ namespace crypto {
 
 static const size_t kSHA256Length = 32;  // Length in bytes of a SHA-256 hash.
 
+// Computes the SHA-256 hash of |input|.
+CRYPTO_EXPORT std::array<uint8_t, kSHA256Length> SHA256Hash(
+    base::span<const uint8_t> input);
+
+// Convenience version of the above that returns the result in a 32-byte
+// string.
+CRYPTO_EXPORT std::string SHA256HashString(base::StringPiece str);
+
 // Computes the SHA-256 hash of the input string 'str' and stores the first
 // 'len' bytes of the hash in the output buffer 'output'.  If 'len' > 32,
 // only 32 bytes (the full hash) are stored in the 'output' buffer.
@@ -27,10 +37,6 @@ CRYPTO_EXPORT void SHA256HashString(base::StringPiece str,
                                     void* output,
                                     size_t len);
 
-// Convenience version of the above that returns the result in a 32-byte
-// string.
-CRYPTO_EXPORT std::string SHA256HashString(base::StringPiece str);
-
 }  // namespace crypto
 
 #endif  // CRYPTO_SHA2_H_