# AWS Encryption SDK for C
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The AWS Encryption SDK for C provides a client-side encryption library for developers who are writing applications in C. It also serves as a foundation for implementations of the AWS Encryption SDK in higher-level programming languages.

Like all implementations of the AWS Encryption SDK, the AWS Encryption SDK for C offers advanced data protection features. These include [envelope encryption](concepts.md#envelope-encryption), additional authenticated data (AAD), and secure, authenticated, symmetric key [algorithm suites](concepts.md#crypto-algorithm), such as 256-bit AES-GCM with key derivation and signing.

All language-specific implementations of the AWS Encryption SDK are fully interoperable. For example, you can encrypt data with the AWS Encryption SDK for C and decrypt it with [any supported language implementation](programming-languages.md), including the [AWS Encryption CLI](crypto-cli.md).

The AWS Encryption SDK for C requires the AWS SDK for C\$1\$1 to interact with AWS Key Management Service (AWS KMS). You need to use it only if you're using the optional [AWS KMS keyring](use-kms-keyring.md). However, the AWS Encryption SDK doesn't require AWS KMS or any other AWS service.

**Learn More**
+ For details about programming with the AWS Encryption SDK for C, see the [C examples](c-examples.md), the [examples](https://github.com/aws/aws-encryption-sdk-c/tree/master/examples) in the [aws-encryption-sdk-c repository](https://github.com/aws/aws-encryption-sdk-c/) on GitHub, and the [AWS Encryption SDK for C API documentation](https://aws.github.io/aws-encryption-sdk-c/html/).
+ For a discussion about how to use the AWS Encryption SDK for C to encrypt data so that you can decrypt it in multiple AWS Regions, see [How to decrypt ciphertexts in multiple regions with the AWS Encryption SDK in C](https://aws.amazon.com/blogs/security/how-to-decrypt-ciphertexts-multiple-regions-aws-encryption-sdk-in-c/) in the AWS Security Blog.

**Topics**
+ [Installing](c-language-installation.md)
+ [Using the C SDK](c-language-using.md)
+ [Examples](c-examples.md)