Java 从S3读取加密数据

我必须从S3存储桶下载数据，数据经过加密，我有kms密钥来解密数据。代码在EC2实例中运行，EC2实例具有IAM角色以从S3读取。 我在link中看到了一个示例代码，但我无法阅读其中的内容

Exception in thread "main" com.amazonaws.SdkClientException: Unable to load credentials into profile [default]: AWS Access Key ID is not specified.
        at com.amazonaws.auth.profile.internal.ProfileStaticCredentialsProvider.fromStaticCredentials(ProfileStaticCredentialsProvider.java:55)
        at com.amazonaws.auth.profile.internal.ProfileStaticCredentialsProvider.<init>(ProfileStaticCredentialsProvider.java:40)
        at com.amazonaws.auth.profile.ProfilesConfigFile.fromProfile(ProfilesConfigFile.java:207)
        at com.amazonaws.auth.profile.ProfilesConfigFile.getCredentials(ProfilesConfigFile.java:160)

线程“main”com.amazonaws.SdkClientException中的异常：无法将凭据加载到配置文件[默认]：未指定AWS访问密钥ID。
在com.amazonaws.auth.profile.internal.ProfileStaticCredentialsProvider.fromStaticCredentials（ProfileStaticCredentialsProvider.java:55）上
位于com.amazonaws.auth.profile.internal.ProfileStaticCredentialsProvider.（ProfileStaticCredentialsProvider.java:40）
在com.amazonaws.auth.profile.ProfilesConfigFile.fromProfile（ProfilesConfigFile.java:207）上
在com.amazonaws.auth.profile.ProfilesConfigFile.getCredentials上（ProfilesConfigFile.java:160）

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有人能告诉我哪里出了问题，或者给出一些关于如何在没有凭据的情况下从S3存储桶读取加密数据的指导方针吗？

我通过提供InstanceProfileCredentialsProvider找到了一个解决方案。下面是代码

 String kms_key = Constants.KMS_key;
        String inputString = null;
        KMSEncryptionMaterialsProvider materialProvider = new KMSEncryptionMaterialsProvider(kms_key);
        AmazonS3EncryptionClient client = new AmazonS3EncryptionClient(InstanceProfileCredentialsProvider.getInstance(),
                materialProvider);
        S3Object downloadedObject = client.getObject(bucketName, filePath);
        if (null != downloadedObject) {
            inputString = convertToString(downloadedObject.getObjectContent());
        }

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我通过提供InstanceProfileCredentialsProvider找到了一个解决方案

 String kms_key = Constants.KMS_key;
        String inputString = null;
        KMSEncryptionMaterialsProvider materialProvider = new KMSEncryptionMaterialsProvider(kms_key);
        AmazonS3EncryptionClient client = new AmazonS3EncryptionClient(InstanceProfileCredentialsProvider.getInstance(),
                materialProvider);
        S3Object downloadedObject = client.getObject(bucketName, filePath);
        if (null != downloadedObject) {
            inputString = convertToString(downloadedObject.getObjectContent());
        }