# Verify a signature signed with the ECDSA mechanism in CloudHSM CLI
<a name="cloudhsm_cli-crypto-verify-ecdsa"></a>

Use the **crypto verify ecdsa** command in CloudHSM CLI to complete the following operations:
+ Confirm a file has been signed in the HSM by a given public key.
+ Verify the signature was generated using the ECDSA signing mechanism.
+ Compare a signed file against a source file and determine whether the two are cryptographically related based on a given ecdsa public key and signing mechanism. 
+  The ECDSA verification function expects the signature in the format `r||s`, where the r and s components are concatenated as raw binary data. 

To use the **crypto verify ecdsa** command, you must first have an EC public key in your AWS CloudHSM cluster. You can import an EC public key using the [Import a PEM format key with CloudHSM CLI](cloudhsm_cli-key-import-pem.md) command with the `verify` attribute set to `true`.

**Note**  
You can generate a signature in CloudHSM CLI with [The crypto sign category in CloudHSM CLI](cloudhsm_cli-crypto-sign.md) subcommands.

## User type
<a name="cloudhsm_cli-crypto-verify-ecdsa-userType"></a>

The following types of users can run this command.
+ Crypto users (CUs)

## Requirements
<a name="cloudhsm_cli-crypto-verify-ecdsa-requirements"></a>
+ To run this command, you must be logged in as a CU.

## Syntax
<a name="cloudhsm_cli-crypto-verify-ecdsa-syntax"></a>

```
aws-cloudhsm > help crypto verify ecdsa
Verify with the ECDSA mechanism

Usage: crypto verify ecdsa --key-filter [<KEY_FILTER>...] --hash-function <HASH_FUNCTION> <--data-path <DATA_PATH>|--data <DATA>> <--signature-path <SIGNATURE_PATH>|--signature <SIGNATURE>>

Options:
      --cluster-id <CLUSTER_ID>
          Unique Id to choose which of the clusters in the config file to run the operation against. If not provided, will fall back to the value provided when interactive mode was started, or error
      --key-filter [<KEY_FILTER>...]
          Key reference (e.g. key-reference=0xabc) or space separated list of key attributes in the form of attr.KEY_ATTRIBUTE_NAME=KEY_ATTRIBUTE_VALUE to select a matching key
      --hash-function <HASH_FUNCTION>
          [possible values: sha1, sha224, sha256, sha384, sha512]
      --data-path <DATA_PATH>
          The path to the file containing the data to be verified
      --data <DATA>
          Base64 encoded data to be verified
      --signature-path <SIGNATURE_PATH>
          The path to where the signature is located
      --signature <SIGNATURE>
          Base64 encoded signature to be verified
      --data-type <DATA_TYPE>
          The type of data passed in, either raw or digest [possible values: raw, digest]
  -h, --help
          Print help
```

## Example
<a name="cloudhsm_cli-crypto-verify-ecdsa-examples"></a>

These examples show how to use **crypto verify ecdsa** to verify a signature that was generated using the ECDSA signing mechanism and `SHA256` hash function. This command uses a public key in the HSM.

**Example: Verify a Base64 encoded signature with Base64 encoded data**  

```
aws-cloudhsm > crypto verify ecdsa --hash-function sha256 --key-filter attr.label=ec-public --data YWJjMTIz --signature 4zki+FzjhP7Z/KqoQvh4ueMAxQQVp7FQguZ2wOS3Q5bzk+Hc5irV5iTkuxQbropPttVFZ8V6FgR2fz+sPegwCw==
{
  "error_code": 0,
  "data": {
    "message": "Signature verified successfully"
  }
}
```

**Example: Verify a signature file with a data file**  

```
aws-cloudhsm > crypto verify ecdsa --hash-function sha256 --key-filter attr.label=ec-public --data-path data.txt --signature-path signature-file
{
   "error_code": 0,
  "data": {
    "message": "Signature verified successfully"
  }
}
```

**Example: Prove false signing relationship**  
This command verifies whether the data located at `/home/data` was signed by a public key with the label `ecdsa-public` using the ECDSA signing mechanism to produce the signature located in `/home/signature`. Because the given arguments do not make up a true signing relationship, the command returns an error message.  

```
aws-cloudhsm > crypto verify ecdsa --hash-function sha256 --key-filter attr.label=ec-public --data aW52YWxpZA== --signature +ogk7M7S3iTqFg3SndJfd91dZFr5Qo6YixJl8JwcvqqVgsVuO6o+VKvTRjz0/V05kf3JJbBLr87Q+wLWcMAJfA==
{
  "error_code": 1,
  "data": "Signature verification failed"
}
```

## Arguments
<a name="cloudhsm_cli-crypto-verify-ecdsa-arguments"></a>

***<CLUSTER\$1ID>***  
The ID of the cluster to run this operation on.  
Required: If multiple clusters have been [configured.](cloudhsm_cli-configs-multi-cluster.md)

***<DATA>***  
Base64 encoded data to be signed.  
Required: Yes (unless provided through data path)

***<DATA\$1PATH>***  
Specifies the location of the data to be signed.  
Required: Yes (unless provided through data path)

***<HASH\$1FUNCTION>***  
Specifies the hash function.   
Valid values:  
+ sha1
+ sha224
+ sha256
+ sha384
+ sha512
Required: Yes

***<KEY\$1FILTER>***  
Key reference (for example, `key-reference=0xabc`) or space separated list of key attributes in the form of `attr.KEY_ATTRIBUTE_NAME=KEY_ATTRIBUTE_VALUE` to select a matching key.  
For a listing of supported CloudHSM CLI key attributes, see Key attributes for CloudHSM CLI.  
Required: Yes

***<SIGNATURE>***  
Base64 encoded signature.  
Required: Yes (unless provided through signature path)

***<SIGNATURE\$1PATH>***  
Specifies the location of the signature.  
Required: Yes (unless provided through signature path)

***<DATA\$1TYPE>***  
 Specifies whether the value of the data parameter should be hashed as part of the signing algorithm. Use `raw` for unhashed data; use `digest` for digests, which are already hashed.   
Valid values:  
+ raw
+ digest

## Related topics
<a name="cloudhsm_cli-crypto-verify-ecdsa-seealso"></a>
+ [The crypto sign category in CloudHSM CLI](cloudhsm_cli-crypto-sign.md)
+ [The crypto verify category in CloudHSM CLI](cloudhsm_cli-crypto-verify.md)