sdk/core: Reimplement Md5OpenSSL using EVP API (#3609)

The MD5_Init/Update/Final functions are deprecated in OpenSSL 3.0 and result in
a compile-time warning. Due to the default usage of -Werror during compilation,
these warnings are treated as errors and prevent the SDK from being built on
Ubuntu 22.04, which ships with OpenSSL by default. The deprecated APIs should
be replaced by the EVP APIs, which are already in use for the SHA family of
functions, and supported on all versions of OpenSSL.

sdk/core/azure-core/src/cryptography/md5.cpp

@@ -10,7 +10,7 @@
 
 #include <bcrypt.h>
 #elif defined(AZ_PLATFORM_POSIX)
-#include <openssl/md5.h>
+#include <openssl/evp.h>
 #endif
 
 #include <stdexcept>
@@ -161,24 +161,45 @@ Azure::Core::Cryptography::Md5Hash::Md5Hash() : m_implementation(std::make_uniqu
 
 class Md5OpenSSL final : public Azure::Core::Cryptography::Hash {
 private:
-  std::unique_ptr<MD5_CTX> m_context;
+  EVP_MD_CTX* m_context;
 
-  void OnAppend(const uint8_t* data, size_t length) { MD5_Update(m_context.get(), data, length); }
+  void OnAppend(const uint8_t* data, size_t length) override
+  {
+    if (1 != EVP_DigestUpdate(m_context, data, length))
+    {
+      throw std::runtime_error("Crypto error while updating Md5Hash.");
+    }
+  }
 
-  std::vector<uint8_t> OnFinal(const uint8_t* data, size_t length)
+  std::vector<uint8_t> OnFinal(const uint8_t* data, size_t length) override
   {
     OnAppend(data, length);
-    unsigned char hash[MD5_DIGEST_LENGTH];
-    MD5_Final(hash, m_context.get());
-    return std::vector<uint8_t>(std::begin(hash), std::end(hash));
+    unsigned int size;
+    unsigned char hash[EVP_MAX_MD_SIZE];
+    if (1 != EVP_DigestFinal(m_context, hash, &size))
+    {
+      throw std::runtime_error("Crypto error while computing Md5Hash.");
+    }
+
+    return std::vector<uint8_t>(std::begin(hash), std::begin(hash) + size);
   }
 
 public:
   Md5OpenSSL()
   {
-    m_context = std::make_unique<MD5_CTX>();
-    MD5_Init(m_context.get());
+    m_context = EVP_MD_CTX_new();
+    if (m_context == NULL)
+    {
+      throw std::runtime_error("Crypto error while creating EVP context.");
+    }
+    if (1 != EVP_DigestInit_ex(m_context, EVP_md5(), NULL))
+    {
+      EVP_MD_CTX_free(m_context);
+      throw std::runtime_error("Crypto error while init Md5Hash.");
+    }
   }
+
+  ~Md5OpenSSL() { EVP_MD_CTX_free(m_context); }
 };
 
 } // namespace