diff --git a/core/sdk-core/src/main/java/software/amazon/awssdk/core/checksums/Algorithm.java b/core/sdk-core/src/main/java/software/amazon/awssdk/core/checksums/Algorithm.java
index cd2b0d7303c1..46813da33da5 100644
--- a/core/sdk-core/src/main/java/software/amazon/awssdk/core/checksums/Algorithm.java
+++ b/core/sdk-core/src/main/java/software/amazon/awssdk/core/checksums/Algorithm.java
@@ -32,7 +32,8 @@ public enum Algorithm {
     SHA1("sha1", 28),
     ;
 
-    private static final Map<String, Algorithm> VALUE_MAP = EnumUtils.uniqueIndex(Algorithm.class, Algorithm::toString);
+    private static final Map<String, Algorithm> VALUE_MAP = EnumUtils.uniqueIndex(Algorithm.class,
+                                                                                  a -> StringUtils.upperCase(a.value));
 
     private final String value;
     private final int length;
@@ -46,12 +47,17 @@ public static Algorithm fromValue(String value) {
         if (value == null) {
             return null;
         }
-        String normalizedValue = StringUtils.lowerCase(value);
-        Algorithm algorithm = VALUE_MAP.get(normalizedValue);
+        // The clients will send the algorithm name in all upper case
+        // try using that name directly and if not found then normalize
+        // it and try again.
+        Algorithm algorithm = VALUE_MAP.get(value);
         if (algorithm == null) {
-            throw new IllegalArgumentException("The provided value is not a valid algorithm " + value);
+            String normalizedValue = StringUtils.upperCase(value);
+            algorithm = VALUE_MAP.get(normalizedValue);
+            if (algorithm == null) {
+                throw new IllegalArgumentException("The provided value is not a valid algorithm " + value);
+            }
         }
-
         return algorithm;
     }
 
diff --git a/core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/util/HttpChecksumResolver.java b/core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/util/HttpChecksumResolver.java
index 86954a67e405..c204c7a4fc4e 100644
--- a/core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/util/HttpChecksumResolver.java
+++ b/core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/util/HttpChecksumResolver.java
@@ -15,9 +15,8 @@
 
 package software.amazon.awssdk.core.internal.util;
 
+import java.util.ArrayList;
 import java.util.List;
-import java.util.Optional;
-import java.util.stream.Collectors;
 import software.amazon.awssdk.annotations.SdkInternalApi;
 import software.amazon.awssdk.core.checksums.Algorithm;
 import software.amazon.awssdk.core.checksums.ChecksumSpecs;
@@ -25,7 +24,6 @@
 import software.amazon.awssdk.core.interceptor.SdkExecutionAttribute;
 import software.amazon.awssdk.core.interceptor.SdkInternalExecutionAttribute;
 import software.amazon.awssdk.core.interceptor.trait.HttpChecksum;
-import software.amazon.awssdk.utils.StringUtils;
 
 /**
  * Class to resolve the different Checksums specs from ExecutionAttributes.
@@ -37,8 +35,11 @@ private HttpChecksumResolver() {
     }
 
     public static ChecksumSpecs getResolvedChecksumSpecs(ExecutionAttributes executionAttributes) {
-        return Optional.ofNullable(executionAttributes.getAttribute(SdkExecutionAttribute.RESOLVED_CHECKSUM_SPECS))
-                       .orElseGet(() -> resolveChecksumSpecs(executionAttributes));
+        ChecksumSpecs checksumSpecs = executionAttributes.getAttribute(SdkExecutionAttribute.RESOLVED_CHECKSUM_SPECS);
+        if (checksumSpecs != null) {
+            return checksumSpecs;
+        }
+        return resolveChecksumSpecs(executionAttributes);
     }
 
     public static ChecksumSpecs resolveChecksumSpecs(ExecutionAttributes executionAttributes) {
@@ -47,9 +48,8 @@ public static ChecksumSpecs resolveChecksumSpecs(ExecutionAttributes executionAt
             return null;
         }
         boolean hasRequestValidation = hasRequestValidationMode(httpChecksumTraitInOperation);
-        String checksumHeaderName = httpChecksumTraitInOperation.requestAlgorithm() != null ?
-            HttpChecksumUtils.httpChecksumHeader(httpChecksumTraitInOperation.requestAlgorithm())
-                                    : null;
+        String requestAlgorithm = httpChecksumTraitInOperation.requestAlgorithm();
+        String checksumHeaderName = requestAlgorithm != null ? HttpChecksumUtils.httpChecksumHeader(requestAlgorithm) : null;
         List<Algorithm> responseValidationAlgorithms = getResponseValidationAlgorithms(httpChecksumTraitInOperation);
 
         return ChecksumSpecs.builder()
@@ -67,16 +67,14 @@ private static boolean hasRequestValidationMode(HttpChecksum httpChecksum) {
     }
 
     private static List<Algorithm> getResponseValidationAlgorithms(HttpChecksum httpChecksumTraitInOperation) {
-        List<Algorithm> responseValidationAlgorithms = null;
-
-        if (httpChecksumTraitInOperation.responseAlgorithms() != null &&
-            !httpChecksumTraitInOperation.responseAlgorithms().isEmpty()) {
-            responseValidationAlgorithms =
-                httpChecksumTraitInOperation.responseAlgorithms().stream().filter(StringUtils::isNotBlank)
-                                            .map(StringUtils::trim)
-                                            .map(Algorithm::fromValue)
-                                            .collect(Collectors.toList());
+        List<String> responseAlgorithms = httpChecksumTraitInOperation.responseAlgorithms();
+        if (responseAlgorithms != null && !responseAlgorithms.isEmpty()) {
+            List<Algorithm> responseValidationAlgorithms = new ArrayList<>(responseAlgorithms.size());
+            for (String algorithmName : responseAlgorithms) {
+                responseValidationAlgorithms.add(Algorithm.fromValue(algorithmName));
+            }
+            return responseValidationAlgorithms;
         }
-        return responseValidationAlgorithms;
+        return null;
     }
 }