Use the base64-encoded signature to verify the instance identity document

This topic explains how to verify the instance identity document using the base64-encoded signature and the AWS RSA public certificate.

To validate the instance identity document using the base64-encoded signature and the AWS RSA public certificate

Connect to the instance.

Retrieve the base64-encoded signature from the instance metadata, convert it to binary, and add it to a file named signature. Use one of the following commands depending on the IMDS version used by the instance.

Retrieve the plaintext instance identity document from the instance metadata and add it to a file named document. Use one of the following commands depending on the IMDS version used by the instance.

Find the RSA public certificate for your Region in AWS public certificates and add the contents to a new file named certificate.
Extract the public key from the AWS RSA public certificate and save it to a file named key.
```
$ openssl x509 -pubkey -noout -in certificate >> key
```
Use OpenSSL dgst command to verify the instance identity document.
```
$ openssl dgst -sha256 -verify key -signature signature document
```
If the signature is valid, the Verification successful message appears.

The command also writes the contents of the instance identity document to a new file named document. You can compare the contents of the of the instance identity document from the instance metadata with the contents of this file using the following commands.
```
$ openssl dgst -sha256 < document
```
```
$ curl -s -H "X-aws-ec2-metadata-token: $TOKEN" http://169.254.169.254/latest/dynamic/instance-identity/document | openssl dgst -sha256
```
If the signature cannot be verified, contact AWS Support.

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Document Conventions

Verify using the PKCS7 signature

Verify using the RSA-2048 signature