diff --git a/config_asm.h b/config_asm.h
index 6cffbb05d..4cd664f78 100644
--- a/config_asm.h
+++ b/config_asm.h
@@ -252,7 +252,7 @@
 // Requires GCC 4.8, Clang 3.3 or Visual Studio 2017
 // Do not use APPLE_CLANG_VERSION; use __ARM_FEATURE_XXX instead.
 #if !defined(CRYPTOPP_ARM_ASIMD_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ARM_ASIMD)
-# if defined(__aarch32__) || defined(__aarch64__) || defined(__arm64__) || defined(_M_ARM64)
+# if defined(__aarch32__) || defined(__aarch64__) || defined(__arm64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 #  if defined(__ARM_NEON) || defined(__ARM_ASIMD) || defined(__ARM_FEATURE_NEON) || defined(__ARM_FEATURE_ASIMD) || \
       (CRYPTOPP_GCC_VERSION >= 40800) || (CRYPTOPP_LLVM_CLANG_VERSION >= 30300) || \
       (CRYPTOPP_APPLE_CLANG_VERSION >= 40000) || (CRYPTOPP_MSC_VERSION >= 1916)
@@ -265,7 +265,7 @@
 // ARMv8 and ASIMD. -march=armv8-a+crc or above must be present
 // Requires GCC 4.8, Clang 3.3 or Visual Studio 2017
 #if !defined(CRYPTOPP_ARM_CRC32_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ARM_CRC32)
-# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 #  if defined(__ARM_FEATURE_CRC32) || (CRYPTOPP_GCC_VERSION >= 40800) || \
       (CRYPTOPP_LLVM_CLANG_VERSION >= 30300) || (CRYPTOPP_APPLE_CLANG_VERSION >= 40300) || \
       (CRYPTOPP_MSC_VERSION >= 1916)
@@ -277,7 +277,7 @@
 // ARMv8 and AES. -march=armv8-a+crypto or above must be present
 // Requires GCC 4.8, Clang 3.3 or Visual Studio 2017
 #if !defined(CRYPTOPP_ARM_AES_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ARM_AES)
-# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 #  if defined(__ARM_FEATURE_CRYPTO) || (CRYPTOPP_GCC_VERSION >= 40800) || \
       (CRYPTOPP_LLVM_CLANG_VERSION >= 30300) || (CRYPTOPP_APPLE_CLANG_VERSION >= 40300) || \
       (CRYPTOPP_MSC_VERSION >= 1916)
@@ -289,7 +289,7 @@
 // ARMv8 and PMULL. -march=armv8-a+crypto or above must be present
 // Requires GCC 4.8, Clang 3.3 or Visual Studio 2017
 #if !defined(CRYPTOPP_ARM_PMULL_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ARM_PMULL)
-# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 #  if defined(__ARM_FEATURE_CRYPTO) || (CRYPTOPP_GCC_VERSION >= 40800) || \
       (CRYPTOPP_LLVM_CLANG_VERSION >= 30300) || (CRYPTOPP_APPLE_CLANG_VERSION >= 40300) || \
       (CRYPTOPP_MSC_VERSION >= 1916)
@@ -301,7 +301,7 @@
 // ARMv8 and SHA-1, SHA-256. -march=armv8-a+crypto or above must be present
 // Requires GCC 4.8, Clang 3.3 or Visual Studio 2017
 #if !defined(CRYPTOPP_ARM_SHA_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ARM_SHA)
-# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 #  if defined(__ARM_FEATURE_CRYPTO) || (CRYPTOPP_GCC_VERSION >= 40800) || \
       (CRYPTOPP_LLVM_CLANG_VERSION >= 30300) || (CRYPTOPP_APPLE_CLANG_VERSION >= 40300) || \
       (CRYPTOPP_MSC_VERSION >= 1916)
@@ -320,7 +320,7 @@
 // ARMv8 and SHA-512, SHA-3. -march=armv8.2-a+crypto or above must be present
 // Requires GCC 8.0, Clang 11.0, Apple Clang 12.0 or Visual Studio 20??
 #if !defined(CRYPTOPP_ARM_SHA3_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ARM_SHA)
-# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 #  if defined(__ARM_FEATURE_SHA3) || (CRYPTOPP_GCC_VERSION >= 80000) || \
       (CRYPTOPP_APPLE_CLANG_VERSION >= 120000) || (CRYPTOPP_LLVM_CLANG_VERSION >= 110000)
 #   define CRYPTOPP_ARM_SHA512_AVAILABLE 1
@@ -333,7 +333,7 @@
 // Requires GCC 8.0, Clang ??? or Visual Studio 20??
 // Do not use APPLE_CLANG_VERSION; use __ARM_FEATURE_XXX instead.
 #if !defined(CRYPTOPP_ARM_SM3_AVAILABLE) && !defined(CRYPTOPP_DISABLE_ARM_SM3)
-# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 #  if defined(__ARM_FEATURE_SM3) || (CRYPTOPP_GCC_VERSION >= 80000)
 #   define CRYPTOPP_ARM_SM3_AVAILABLE 1
 #   define CRYPTOPP_ARM_SM4_AVAILABLE 1
@@ -344,7 +344,7 @@
 // Limit the <arm_neon.h> include.
 #if !defined(CRYPTOPP_ARM_NEON_HEADER)
 # if defined(CRYPTOPP_ARM_NEON_AVAILABLE) || defined (CRYPTOPP_ARM_ASIMD_AVAILABLE)
-#  if !defined(_M_ARM64)
+#  if !defined(_M_ARM64) &&!defined(_M_ARM64EC)
 #   define CRYPTOPP_ARM_NEON_HEADER 1
 #  endif
 # endif
diff --git a/config_cpu.h b/config_cpu.h
index 129f5e58b..167893596 100644
--- a/config_cpu.h
+++ b/config_cpu.h
@@ -52,7 +52,7 @@
 	#define CRYPTOPP_BOOL_X86 ...
 #elif (defined(__ILP32__) || defined(_ILP32)) && defined(__x86_64__)
 	#define CRYPTOPP_BOOL_X32 1
-#elif (defined(_M_X64) || defined(__x86_64__))
+#elif ((defined(_M_X64) && !defined(_M_ARM64EC)) || defined(__x86_64__))
 	#define CRYPTOPP_BOOL_X64 1
 #elif (defined(_M_IX86) || defined(__i386__) || defined(__i386) || defined(_X86_) || defined(__I86__) || defined(__INTEL__))
 	#define CRYPTOPP_BOOL_X86 1
@@ -79,7 +79,7 @@
 	// Microsoft added ARM64 define December 2017.
 	#define CRYPTOPP_BOOL_ARMV8 1
 #endif
-#if defined(__arm64__) || defined(__aarch64__) || defined(_M_ARM64)
+#if defined(__arm64__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 	#define CRYPTOPP_BOOL_ARM64 1
 #elif defined(__arm__) || defined(_M_ARM)
 	#define CRYPTOPP_BOOL_ARM32 1
diff --git a/cpu.cpp b/cpu.cpp
index cdcaf3888..04f3b93e3 100644
--- a/cpu.cpp
+++ b/cpu.cpp
@@ -22,7 +22,7 @@
 
 // For IsProcessorFeaturePresent on Microsoft Arm64 platforms,
 // https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-isprocessorfeaturepresent
-#if defined(_WIN32) && defined(_M_ARM64)
+#if defined(_WIN32) && (defined(_M_ARM64) || defined(_M_ARM64EC))
 # include <Windows.h>
 # include <processthreadsapi.h>
 #endif
@@ -854,7 +854,7 @@ inline bool CPU_QueryARMv7()
 #elif defined(__APPLE__) && defined(__arm__)
 	// Apple hardware is ARMv7 or above.
 	return true;
-#elif defined(_WIN32) && defined(_M_ARM64)
+#elif defined(_WIN32) && (defined(_M_ARM64) || defined(_M_ARM64EC))
 	// Windows 10 ARM64 is only supported on Armv8a and above
 	return true;
 #endif
@@ -884,7 +884,7 @@ inline bool CPU_QueryNEON()
 	// Core feature set for Aarch32 and Aarch64.
 	if (IsAppleMachineARMv8())
 		return true;
-#elif defined(_WIN32) && defined(_M_ARM64)
+#elif defined(_WIN32) && (defined(_M_ARM64) || defined(_M_ARM64EC))
 	// Windows 10 ARM64 is only supported on Armv8a and above
 	if (IsProcessorFeaturePresent(PF_ARM_V8_INSTRUCTIONS_AVAILABLE) != 0)
 		return true;
@@ -912,7 +912,7 @@ inline bool CPU_QueryCRC32()
 	// M1 processor
 	if (IsAppleMachineARMv82())
 		return true;
-#elif defined(_WIN32) && defined(_M_ARM64)
+#elif defined(_WIN32) && (defined(_M_ARM64) || defined(_M_ARM64EC))
 	if (IsProcessorFeaturePresent(PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE) != 0)
 		return true;
 #endif
@@ -939,7 +939,7 @@ inline bool CPU_QueryPMULL()
 	// M1 processor
 	if (IsAppleMachineARMv82())
 		return true;
-#elif defined(_WIN32) && defined(_M_ARM64)
+#elif defined(_WIN32) && (defined(_M_ARM64) || defined(_M_ARM64EC))
 	if (IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE) != 0)
 		return true;
 #endif
@@ -966,7 +966,7 @@ inline bool CPU_QueryAES()
 	// M1 processor
 	if (IsAppleMachineARMv82())
 		return true;
-#elif defined(_WIN32) && defined(_M_ARM64)
+#elif defined(_WIN32) && (defined(_M_ARM64) || defined(_M_ARM64EC))
 	if (IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE) != 0)
 		return true;
 #endif
@@ -993,7 +993,7 @@ inline bool CPU_QuerySHA1()
 	// M1 processor
 	if (IsAppleMachineARMv82())
 		return true;
-#elif defined(_WIN32) && defined(_M_ARM64)
+#elif defined(_WIN32) && (defined(_M_ARM64) || defined(_M_ARM64EC))
 	if (IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE) != 0)
 		return true;
 #endif
@@ -1020,7 +1020,7 @@ inline bool CPU_QuerySHA256()
 	// M1 processor
 	if (IsAppleMachineARMv82())
 		return true;
-#elif defined(_WIN32) && defined(_M_ARM64)
+#elif defined(_WIN32) && (defined(_M_ARM64) || defined(_M_ARM64EC))
 	if (IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE) != 0)
 		return true;
 #endif
diff --git a/donna_64.h b/donna_64.h
index 75296e1df..b8cb728c6 100644
--- a/donna_64.h
+++ b/donna_64.h
@@ -16,8 +16,12 @@
 
 #if defined(CRYPTOPP_MSC_VERSION)
 # include <intrin.h>
-# pragma intrinsic(_umul128)
-# pragma intrinsic(__shiftright128)
+# ifndef _M_ARM64EC
+#  pragma intrinsic(_umul128)
+#  pragma intrinsic(__shiftright128)
+# else
+#  include <minwindef.h>
+# endif
 #endif
 
 NAMESPACE_BEGIN(CryptoPP)
diff --git a/integer.cpp b/integer.cpp
index bf95ac792..7515bb6c9 100644
--- a/integer.cpp
+++ b/integer.cpp
@@ -76,6 +76,9 @@
 #include <iostream>
 
 #if (CRYPTOPP_MSC_VERSION >= 1400) && !defined(_M_ARM)
+	#ifdef _M_ARM64EC
+		#include <minwindef.h> // __shiftleft128
+	#endif
 	#include <intrin.h>
 #endif
 
diff --git a/lea_simd.cpp b/lea_simd.cpp
index a016cb38e..1b36b61fa 100644
--- a/lea_simd.cpp
+++ b/lea_simd.cpp
@@ -39,7 +39,7 @@
 # include <arm_acle.h>
 #endif
 
-#if defined(_M_ARM64)
+#if defined(_M_ARM64) || defined(_M_ARM64EC)
 # include "adv_simd.h"
 #endif
 
diff --git a/misc.cpp b/misc.cpp
index 23d717b03..b69480a31 100644
--- a/misc.cpp
+++ b/misc.cpp
@@ -35,7 +35,7 @@
 #  include <immintrin.h>
 # endif
 
-# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+# if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 #  if (CRYPTOPP_ARM_NEON_HEADER) || (CRYPTOPP_ARM_ASIMD_AVAILABLE)
 #   include <arm_neon.h>
 #  endif
@@ -96,7 +96,7 @@ void xorbuf(byte *buf, const byte *mask, size_t count)
 		buf += 16; mask += 16; count -= 16;
 	}
 # endif
-# if defined(__aarch64__) || defined(__aarch32__) || defined(_M_ARM64)
+# if defined(__aarch64__) || defined(__aarch32__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 	while (count >= 16)
 	{
 		vst1q_u8(buf, veorq_u8(vld1q_u8(buf), vld1q_u8(mask)));
@@ -170,7 +170,7 @@ void xorbuf(byte *output, const byte *input, const byte *mask, size_t count)
 		output += 16; input += 16; mask += 16; count -= 16;
 	}
 # endif
-# if defined(__aarch64__) || defined(__aarch32__) || defined(_M_ARM64)
+# if defined(__aarch64__) || defined(__aarch32__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 	while (count >= 16)
 	{
 		vst1q_u8(output, veorq_u8(vld1q_u8(input), vld1q_u8(mask)));
diff --git a/neon_simd.cpp b/neon_simd.cpp
index 602ba0e97..a864469f7 100644
--- a/neon_simd.cpp
+++ b/neon_simd.cpp
@@ -49,7 +49,7 @@ extern "C" {
 
 bool CPU_ProbeARMv7()
 {
-#if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+#if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
     return false;
 #elif defined(CRYPTOPP_NO_CPU_FEATURE_PROBES)
     return false;
@@ -132,7 +132,7 @@ bool CPU_ProbeARMv7()
 
 bool CPU_ProbeNEON()
 {
-#if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+#if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
     return true;
 #elif defined(CRYPTOPP_NO_CPU_FEATURE_PROBES)
     return false;
diff --git a/rijndael_simd.cpp b/rijndael_simd.cpp
index c3421b3e9..ee8862bae 100644
--- a/rijndael_simd.cpp
+++ b/rijndael_simd.cpp
@@ -43,7 +43,7 @@
 # endif
 #endif
 
-#if defined(_M_ARM64)
+#if defined(_M_ARM64) || defined(_M_ARM64EC)
 # include "adv_simd.h"
 #endif
 
diff --git a/simon128_simd.cpp b/simon128_simd.cpp
index 8c0b2e31d..c3a0d6c83 100644
--- a/simon128_simd.cpp
+++ b/simon128_simd.cpp
@@ -39,7 +39,7 @@
 # include <arm_acle.h>
 #endif
 
-#if defined(_M_ARM64)
+#if defined(_M_ARM64) || defined(_M_ARM64EC)
 # include "adv_simd.h"
 #endif
 
@@ -63,7 +63,7 @@ using CryptoPP::vec_swap;  // SunCC
 #if (CRYPTOPP_ARM_NEON_AVAILABLE)
 
 // Missing from Microsoft's ARM A-32 implementation
-#if defined(CRYPTOPP_MSC_VERSION) && !defined(_M_ARM64)
+#if defined(CRYPTOPP_MSC_VERSION) && !defined(_M_ARM64) && !defined(_M_ARM64EC)
 inline uint64x2_t vld1q_dup_u64(const uint64_t* ptr)
 {
     return vmovq_n_u64(*ptr);
diff --git a/speck128_simd.cpp b/speck128_simd.cpp
index a30d79e5e..90f48c915 100644
--- a/speck128_simd.cpp
+++ b/speck128_simd.cpp
@@ -39,7 +39,7 @@
 # include <arm_acle.h>
 #endif
 
-#if defined(_M_ARM64)
+#if defined(_M_ARM64) || defined(_M_ARM64EC)
 # include "adv_simd.h"
 #endif
 
@@ -62,7 +62,7 @@ using CryptoPP::word64;
 #if (CRYPTOPP_ARM_NEON_AVAILABLE)
 
 // Missing from Microsoft's ARM A-32 implementation
-#if defined(CRYPTOPP_MSC_VERSION) && !defined(_M_ARM64)
+#if defined(CRYPTOPP_MSC_VERSION) && !defined(_M_ARM64) && !defined(_M_ARM64EC)
 inline uint64x2_t vld1q_dup_u64(const uint64_t* ptr)
 {
     return vmovq_n_u64(*ptr);
diff --git a/xts.cpp b/xts.cpp
index f5d385a87..723b5293d 100644
--- a/xts.cpp
+++ b/xts.cpp
@@ -24,7 +24,7 @@
 # include <emmintrin.h>
 #endif
 
-#if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+#if defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 # if (CRYPTOPP_ARM_NEON_HEADER) || (CRYPTOPP_ARM_ASIMD_AVAILABLE)
 #  include <arm_neon.h>
 # endif
@@ -65,14 +65,14 @@ inline void XorBuffer(byte *output, const byte *input, const byte *mask, size_t
 #if defined(CRYPTOPP_DISABLE_ASM)
     xorbuf(output, input, mask, count);
 
-#elif defined(__SSE2__) || defined(_M_X64)
+#elif defined(__SSE2__) || (defined(_M_X64) && !defined(_M_ARM64EC))
     for (size_t i=0; i<count; i+=16)
         _mm_storeu_si128(M128_CAST(output+i),
             _mm_xor_si128(
                 _mm_loadu_si128(CONST_M128_CAST(input+i)),
                 _mm_loadu_si128(CONST_M128_CAST(mask+i))));
 
-#elif defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64)
+#elif defined(__aarch32__) || defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
     for (size_t i=0; i<count; i+=16)
         vst1q_u8(output+i, veorq_u8(vld1q_u8(input+i), vld1q_u8(mask+i)));