AWS Documentation » AWS KMS » Developer Guide » Authentication and Access Control for AWS KMS » Using Policy Conditions with AWS KMS

Using Policy Conditions with AWS KMS

You can specify conditions in the key policies and IAM policies that control access to AWS KMS resources. The policy statement is effective only when the conditions are true. For example, you might want a policy statement to take effect only after a specific date. Or, you might want a policy statement to control access only when a specific value appears in an API request.

To specify conditions, you use predefined condition keys in the Condition element of a policy statement with IAM condition policy operators. Some condition keys apply generally to AWS; others are specific to AWS KMS.

AWS Global Condition Keys

AWS provides global condition keys, a set of predefined condition keys for all AWS services that use IAM for access control. For example, you can use the aws:PrincipalType condition key to allow access only when the principal in the request is the type you specify.

AWS KMS supports all global condition keys, including the aws:TagKeys and aws:RequestTag condition keys that control access based on the resource tag in the request. This condition key is supported by some, but not all, AWS services.

Topics

• Using the IP Address Condition in Policies with AWS KMS Permissions
• Using VPC Endpoint Conditions in Policies with AWS KMS Permissions

Using the IP Address Condition in Policies with AWS KMS Permissions

You can use AWS KMS to protect your data in an integrated AWS service. But use caution when specifying the IP address condition operators or the aws:SourceIp condition key in the same policy statement that allows or denies access to AWS KMS. For example, the policy in AWS: Denies Access to AWS Based on the Source IP restricts AWS actions to requests from the specified IP range.

Consider this scenario:

1. You attach a policy like the one shown at AWS: Denies Access to AWS Based on the Source IP to an IAM user. You set the value of the aws:SourceIp condition key to the range of IP addresses for the user's company. This IAM user has other policies attached that allow it to use Amazon EBS, Amazon EC2, and AWS KMS.

2. The user attempts to attach an encrypted EBS volume to an EC2 instance. This action fails with an authorization error even though the user has permission to use all the relevant services.

Step 2 fails because the request to AWS KMS to decrypt the volume's encrypted data key comes from an IP address that is associated with the Amazon EC2 infrastructure. To succeed, the request must come from the IP address of the originating user. Because the policy in step 1 explicitly denies all requests from IP addresses other than those specified, Amazon EC2 is denied permission to decrypt the EBS volume's encrypted data key.

Also, the aws:sourceIP condition key is not effective when the request comes from an Amazon VPC endpoint. To restrict requests to a VPC endpoint, including an AWS KMS VPC endpoint, use the aws:sourceVpce or aws:sourceVpc condition keys. For more information, see VPC Endpoints - Controlling the Use of Endpoints in the Amazon VPC User Guide.

Using VPC Endpoint Conditions in Policies with AWS KMS Permissions

AWS KMS supports Amazon Virtual Private Cloud (Amazon VPC) endpoints that are powered by AWS PrivateLink. You can use the following global condition keys in IAM policies to allow or deny access to a particular VPC or VPC endpoint. You can also use these global condition keys in AWS KMS key policies to restrict access to AWS KMS CMKs to requests from the VPC or VPC endpoint.

• aws:SourceVpc limits access to requests from the specified VPC.

• aws:SourceVpce limits access to requests from the specified VPC endpoint.

If you use these condition keys in a key policy statement that allows or denies access to AWS KMS CMKs, you might inadvertently deny access to services that use AWS KMS on your behalf.

Take care to avoid a situation like the IP address condition keys example. If you restrict requests for a CMK to a VPC or VPC endpoint, calls to AWS KMS from an integrated service, such as Amazon S3 or Amazon EBS, might fail. This can happen even if the source request ultimately originates in the VPC or from the VPC endpoint.

AWS KMS Condition Keys

AWS KMS provides an additional set of predefined condition keys that you can use in key policies and IAM policies. These condition keys are specific to AWS KMS. For example, you can use the kms:EncryptionContext condition key to require a particular encryption context when controlling access to an AWS KMS customer master key (CMK).

The following topics describe each AWS KMS condition key and include example policy statements that demonstrate policy syntax.

Topics

• kms:BypassPolicyLockoutSafetyCheck
• kms:CallerAccount
• kms:EncryptionContext:
• kms:EncryptionContextKeys
• kms:ExpirationModel
• kms:GrantConstraintType
• kms:GrantIsForAWSResource
• kms:GrantOperations
• kms:GranteePrincipal
• kms:KeyOrigin
• kms:ReEncryptOnSameKey
• kms:RetiringPrincipal
• kms:ValidTo
• kms:ViaService
• kms:WrappingAlgorithm
• kms:WrappingKeySpec

kms:BypassPolicyLockoutSafetyCheck

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:BypassPolicyLockoutSafetyCheck	Boolean	CreateKey PutKeyPolicy	CreateKey: IAM policies only PutKeyPolicy: IAM and key policies

The kms:BypassPolicyLockoutSafetyCheck condition key controls access to the CreateKey and PutKeyPolicy operations based on the value of the BypassPolicyLockoutSafetyCheck parameter in the request.

The following example IAM policy statement prevents users from bypassing the policy lockout safety check by denying them permission to create CMKs when the value of the BypassPolicyLockoutSafetyCheck parameter in the CreateKey request is true.

{
  "Version": "2012-10-17",
  "Statement": {
    "Effect": "Deny",
    "Action": "kms:CreateKey",
    "Resource": "*",
    "Condition": {
      "Bool": {
        "kms:BypassPolicyLockoutSafetyCheck": true
      }
    }
  }
}

You can also use the kms:BypassPolicyLockoutSafetyCheck condition key in an IAM policy or key policy to control access to the PutKeyPolicy operation. The following example policy statement from a key policy prevents users from bypassing the policy lockout safety check when changing the policy of a CMK.

Instead of using an explicit Deny, this policy statement uses Allow with the Null condition operator to allow access only when the request does not include the BypassPolicyLockoutSafetyCheck parameter. When the parameter is not used, the default value is false. This slightly weaker policy statement can be overriden in the rare case that a bypass is necessary.

{
  "Version": "2012-10-17",
  "Statement": {
    "Effect": "Allow",
    "Action": "kms:PutKeyPolicy",
    "Resource": "*",
    "Condition": {
      "Null": {
        "kms:BypassPolicyLockoutSafetyCheck": true
      }
    }
  }
}

See Also

• kms:KeyOrigin

kms:CallerAccount

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:CallerAccount	String	The kms:CallerAccount condition key exists for all AWS KMS operations except for these: CreateKey, GenerateRandom, ListAliases, ListKeys, ListRetirableGrants, RetireGrant.	Key policies only

You can use this condition key to allow or deny access to all identities (IAM users and roles) in an AWS account. In key policies, you use the Principal element to specify the identities to which the policy statement applies. The syntax for the Principal element does not provide a way to specify all identities in an AWS account. But you can achieve this effect by combining this condition key with a Principal element that specifies all AWS identities.

For example, the following policy statement demonstrates how to use the kms:CallerAccount condition key. This policy statement is in the key policy for the AWS managed CMK for Amazon EBS. It combines a Principal element that specifies all AWS identities with the kms:CallerAccount condition key to effectively allow access to all identities in AWS account 111122223333. It contains an additional AWS KMS condition key (kms:ViaService) to further limit the permissions by only allowing requests that come through Amazon EBS. For more information, see kms:ViaService.

{
  "Sid": "Allow access through EBS for all principals in the account that are authorized to use EBS",
  "Effect": "Allow",
  "Principal": {"AWS": "*"},
  "Condition": {
    "StringEquals": {
      "kms:CallerAccount": "111122223333",
      "kms:ViaService": "ec2.us-west-2.amazonaws.com"
    }
  },
  "Action": [
    "kms:Encrypt",
    "kms:Decrypt",
    "kms:ReEncrypt*",
    "kms:GenerateDataKey*",
    "kms:CreateGrant",
    "kms:DescribeKey"
  ],
  "Resource": "*"
}

kms:EncryptionContext:

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:EncryptionContext:	String	CreateGrant Encrypt Decrypt GenerateDataKey GenerateDataKeyWithoutPlaintext ReEncrypt	IAM and key policies

You can use the kms:EncryptionContext: condition key prefix to control access to a CMK based on the encryption context in a request for a cryptographic operation. Use this condition key prefix to evaluate both the key and the value in the encryption context pair. To evaluate only the encryption context keys, use the kms:EncryptionContextKeys condition key.

An encryption context is a set of nonsecret key–value pairs that you can include in a request for any AWS KMS cryptographic operation (Encrypt, Decrypt, GenerateDataKey, GenerateDataKeyWithoutPlaintext, and ReEncrypt) and the CreateGrant operation. When you specify an encryption context in an encryption operation, you must specify the same encryption context in the decryption operation. Otherwise, the decryption request fails.

To use the kms:EncryptionContext: condition key prefix, replace the encryption_context_key placeholder with the encryption context key. Replace the encryption_context_value placeholder with the encryption context value.

"kms:EncryptionContext:encryption_context_key": "encryption_context_value"

For example, the following condition key specifies an encryption context in which the key is AppName and the value is ExampleApp.

"kms:EncryptionContext:AppName": "ExampleApp"

The following example key policy statement uses this condition key. This policy allows the principal to use the CMK in a GenerateDataKey request only when the encryption context in the request is "AppName": "ExampleApp".

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:role/RoleForExampleApp"
  },
  "Action": "kms:GenerateDataKey",
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:EncryptionContext:AppName": "ExampleApp"
    }
  }
}

To require more than one encryption context pair, you can include multiple instances of the kms:EncryptionContext: condition. For example, the following example policy statement requires both of the following encryption context pairs. The order in which the pairs are specified does not matter.

• "AppName": "ExampleApp"

• "FilePath": "/var/opt/secrets/"

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:role/RoleForExampleApp"
  },
  "Action": "kms:GenerateDataKey",
  "Resource": "*",
  "Condition": {
    "StringEquals": { 
      "kms:EncryptionContext:AppName": "ExampleApp",
      "kms:EncryptionContext:FilePath": "/var/opt/secrets/"
    }
  }
}

The encryption context that is specified in a decryption operation must be an exact, case-sensitive match for the encryption context that is specified in the encryption operation. Only the order of pairs in an encryption context with multiple pair can vary.

However, in policy conditions, the condition key is not case sensitive. The case sensitivity of the condition value is determined by the policy condition operator that you use, such as StringEquals or StringEqualsIgnoreCase.

As such, the condition key, which consists of the kms:EncryptionContext: prefix and the encryption_context_key replacement, is not case sensitive. A policy that uses this condition does not check the case of either element of the condition key. The case sensitivity of the value, that is, the encryption_context_value replacement, is determined by the policy condition operator.

For example, the following policy statement allows the operation when the encryption context includes an Appname key, regardless of its capitalization. The StringEquals condition requires that ExampleApp be capitalized as it is specified.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:role/RoleForExampleApp"
  },
  "Action": "kms:Decrypt",
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:EncryptionContext:Appname": "ExampleApp"
    }
  }
}

To require a case-sensitive encryption context key, use the kms:EncryptionContextKeys policy condition with a case-sensitive condition operator, such as StringEquals. In this policy condition, because the encryption context key is the policy condition value, its case sensitivity is determined by the condition operator.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:role/RoleForExampleApp"
  },
  "Action": "kms:GenerateDataKey",
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:EncryptionContextKey": "AppName"
    }
  }
}

To require a case-sensitive evaluation of both the encryption context key and value, use the kms:EncryptionContextKey and kms:EncryptionContext: policy conditions together in the same policy statement. For example, in the following example policy statement, because the StringEquals operator is case sensitive, both the encryption context key and the encryption context value are case sensitive.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:role/RoleForExampleApp"
  },
  "Action": "kms:GenerateDataKey",
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:EncryptionContextKey": "AppName",
      "kms:EncryptionContext:AppName": "ExampleApp"
    }
  }
}

See Also

• kms:EncryptionContextKeys

• kms:GrantConstraintType

kms:EncryptionContextKeys

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:EncryptionContextKeys	String (list)	CreateGrant Encrypt Decrypt GenerateDataKey GenerateDataKeyWithoutPlaintext ReEncrypt	IAM and key policies

You can use the kms:EncryptionContextKeys condition key to control access to a CMK based on the encryption context in a request for a cryptographic operation. Use this condition key prefix to evaluate only the key in each encryption context pair. To evaluate both the key and the value,, use the kms:EncryptionContext: condition key prefix.

You can use this condition key to control access based on the encryption context in the AWS KMS API request. Encryption context is a set of key–value pairs that you can include in AWS KMS cryptographic operations (Encrypt, Decrypt, GenerateDataKey, GenerateDataKeyWithoutPlaintext, and ReEncrypt) and the CreateGrant operation.

The following example policy statement uses the kms:EncryptionContextKeys condition key to allow use of a CMK for the specified operations only when the encryption context in the request includes the AppName key, regardless of its value.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:role/RoleForExampleApp"
  },
  "Action": [
    "kms:Encrypt",
    "kms:GenerateDataKey*"
  ],
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:EncryptionContextKeys": "AppName"
    }
  }
}

Because the StringEquals condition operation is case sensitive, the previous policy statement requires the spelling and case of the encryption context key. But you can use a condition operator that ignores the case of the key, such as StringEqualsIgnoreCase.

You can specify multiple encryption context keys in each condition. For example, the following policy statement allows the specified operations only when the encryption context in the request includes both the AppName and FilePath keys, regardless of their values. The order of keys in the encryption context does not matter.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:role/RoleForExampleApp"
  },
  "Action": [
    "kms:Encrypt",
    "kms:GenerateDataKey*"
  ],
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:EncryptionContextKeys": [
        "AppName",
        "FilePath"
      ]
    }
  }
}

You can also use the kms:EncryptionContextKeys condition key to require an encryption context in cryptographic operations that use the CMK.

The following example key policy statement uses the kms:EncryptionContextKeys condition key with the Null condition operator to allow access to CMK only when the kms:EncryptionContextKeys condition key exists (is not null) in the API request. It does not check the keys or values of the encryption context, only that the encryption context exists.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:role/RoleForExampleApp"
  },
  "Action": [
    "kms:Encrypt",
    "kms:GenerateDataKey*"
  ],
  "Resource": "*",
  "Condition": {
    "Null": {
      "kms:EncryptionContextKeys": false
    }
  }
}

See Also

• kms:EncryptionContext:

• kms:GrantConstraintType

kms:ExpirationModel

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:ExpirationModel	String	ImportKeyMaterial	IAM and key policies

The kms:ExpirationModel condition key controls access to the ImportKeyMaterial operation based on the value of the ExpirationModel parameter in the request.

ExpirationModel is an optional parameter that determines whether the imported key material expires. Valid values are KEY_MATERIAL_EXPIRES and KEY_MATERIAL_DOES_NOT_EXPIRE. KEY_MATERIAL_EXPIRES is the default value.

The expiration date and time is determined by the value of the ValidTo parameter. The ValidTo parameter is required unless the value of the ExpirationModel parameter is KEY_MATERIAL_DOES_NOT_EXPIRE. You can also use the kms:ValidTo condition key to require a particular expiration date as a condition for access.

The following example policy statement uses the kms:ExpirationModel condition key to allow a user to import key material into a CMK only when the request includes the ExpirationModel parameter and its value is KEY_MATERIAL_DOES_NOT_EXPIRE.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:ImportKeyMaterial",
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:ExpirationModel": "KEY_MATERIAL_DOES_NOT_EXPIRE"
    }
  }
}

You can also use the kms:ExpirationModel condition key to allow a user to import key material only when the key material expires, without specifying an expiration date in the condition. The following example policy statement uses the kms:ExpirationModel condition key with the Null condition operator to allow a user to import key material only when the request does not have an ExpirationModel parameter.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:ImportKeyMaterial",
  "Resource": "*",
  "Condition": {
    "Null": {
      "kms:ExpirationModel": true
    }
  }
}

See Also

• kms:ValidTo

• kms:WrappingAlgorithm

• kms:WrappingKeySpec

kms:GrantConstraintType

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:GrantConstraintType	String	CreateGrant	IAM and key policies

You can use this condition key to control access to the CreateGrant operation based on the type of grant constraint in the request.

When you create a grant, you can optionally specify a grant constraint to allow the operations that the grant permit only when a particular encryption context is present. The grant constraint can be one of two types: EncryptionContextEquals or EncryptionContextSubset. You can use this condition key to check that the request contains one type or the other.

The following example policy statement uses the kms:GrantConstraintType condition key to allow a user to create grants only when the request includes an EncryptionContextEquals grant constraint. The example shows a policy statement in a key policy.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:CreateGrant",
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:GrantConstraintType": "EncryptionContextEquals"
    }
  }
}

See Also

• kms:EncryptionContext:

• kms:EncryptionContextKeys

• kms:GrantIsForAWSResource

• kms:GrantOperations

• kms:GranteePrincipal

• kms:RetiringPrincipal

kms:GrantIsForAWSResource

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:GrantIsForAWSResource	Boolean	CreateGrant	IAM and key policies

You can use this condition key to control access to the CreateGrant operation based on whether the grant is created in the context of an AWS service integrated with AWS KMS. This condition key is set to true when one of the following integrated services is used to create the grant:

• Amazon Elastic Block Store (Amazon EBS) – For more information, see How Amazon Elastic Block Store (Amazon EBS) Uses AWS KMS.

• Amazon Relational Database Service (Amazon RDS) – For more information, see How Amazon Relational Database Service (Amazon RDS) Uses AWS KMS.

• Amazon Redshift – For more information, see How Amazon Redshift Uses AWS KMS.

• AWS Certificate Manager (ACM) – For more information, see ACM Private Key Security in the AWS Certificate Manager User Guide.

For example, the following policy statement uses the kms:GrantIsForAWSResource condition key to allow a user to create grants only through one of the integrated services in the preceding list. It does not allow the user to create grants directly. The example shows a policy statement in a key policy.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:CreateGrant",
  "Resource": "*",
  "Condition": {
    "Bool": {
      "kms:GrantIsForAWSResource": true
    }
  }
}

See Also

• kms:GrantConstraintType

• kms:GrantOperations

• kms:GranteePrincipal

• kms:RetiringPrincipal

kms:GrantOperations

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:GrantOperations	String	CreateGrant	IAM and key policies

You can use this condition key to control access to the CreateGrant operation based on the grant operations in the request. For example, you can allow a user to create grants that delegate permission to encrypt but not decrypt.

The following example policy statement uses the kms:GrantOperations condition key to allow a user to create grants that delegate permission to encrypt and reencrypt when this CMK is the destination CMK. The example shows a policy statement in a key policy.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:CreateGrant",
  "Resource": "*",
  "Condition": {
    "ForAllValues:StringEquals": {
      "kms:GrantOperations": [
        "Encrypt",
        "ReEncryptTo"
      ]
    }
  }
}

See Also

• kms:GrantConstraintType

• kms:GrantIsForAWSResource

• kms:GranteePrincipal

• kms:RetiringPrincipal

kms:GranteePrincipal

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:GranteePrincipal	String	CreateGrant	IAM and key policies

You can use this condition key to control access to the CreateGrant operation based on the value of the GranteePrincipal parameter in the request. For example, you can allow a user to create grants to use a CMK only when the grantee principal in the CreateGrant request matches the principal specified in the condition statement.

The following example policy statement uses the kms:GranteePrincipal condition key to allow a user to create grants for a CMK only when the grantee principal in the grant is the LimitedAdminRole.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:CreateGrant",
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:GranteePrincipal": "arn:aws:iam::111122223333:role/LimitedAdminRole"
    }
  }
}

See Also

• kms:GrantConstraintType

• kms:GrantIsForAWSResource

• kms:GrantOperations

• kms:RetiringPrincipal

kms:KeyOrigin

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:KeyOrigin	String	CreateKey	IAM policies

You can use this condition key to control access to the CreateKey operation based on the value of the Origin parameter in the request. Valid values for Origin are AWS_KMS, AWS_CLOUDHSM, and EXTERNAL.

For example, you can allow a user to create a CMK only when the key material is generated in KMS (AWS_KMS), only when the key material is generated in an AWS CloudHSM cluster that is associated with a custom key store (AWS_CLOUDHSM), or only when the key material is imported from an external source (EXTERNAL).

The following example policy statement uses the kms:KeyOrigin condition key to allow a user to create a CMK only when the key origin is EXTERNAL, that is, the key material is imported.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:CreateKey",
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:KeyOrigin": "EXTERNAL"
    }
  }
}

See Also

• kms:BypassPolicyLockoutSafetyCheck

kms:ReEncryptOnSameKey

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:ReEncryptOnSameKey	Boolean	ReEncrypt	IAM and key policies

You can use this condition key to control access to the ReEncrypt operation based on whether the request specifies a destination CMK that is the same one used for the original encryption. For example, the following policy statement uses the kms:ReEncryptOnSameKey condition key to allow a user to reencrypt only when the destination CMK is the same one used for the original encryption. The example shows a policy statement in a key policy.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:ReEncrypt*",
  "Resource": "*",
  "Condition": {
    "Bool": {
      "kms:ReEncryptOnSameKey": true
    }
  }
}

kms:RetiringPrincipal

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:RetiringPrincipal	String (list)	CreateGrant	IAM and key policies

You can use this condition key to control access to the CreateGrant operation based on the value of the RetiringPrincipal parameter in the request. For example, you can allow a user to create grants to use a CMK only when the RetiringPrincipal in the CreateGrant request matches the RetiringPrincipal in the condition statement.

The following example policy statement allows a user to create grants for the CMK. The kms:RetiringPrincipal condition key restricts the permission to CreateGrant requests where the retiring principal in the grant is either the LimitedAdminRole or the OpsAdmin user.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:CreateGrant",
  "Resource": "*",
  "Condition": {
    "ForAnyValue:StringEquals": {
      "kms:RetiringPrincipal": [ 
         "arn:aws:iam::111122223333:role/LimitedAdminRole",
         "arn:aws:iam::111122223333:user/OpsAdmin"
      ]
    }
  }
}

See Also

• kms:GrantConstraintType

• kms:GrantIsForAWSResource

• kms:GrantOperations

• kms:GranteePrincipal

kms:ValidTo

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:ValidTo	Timestamp	ImportKeyMaterial	IAM and key policies

The kms:ValidTo condition key controls access to the ImportKeyMaterial operation based on the value of the ValidTo parameter in the request, which determines when the imported key material expires. The value is expressed in Unix time.

By default, the ValidTo parameter is required in an ImportKeyMaterial request. However, if the value of the ExpirationModel parameter is KEY_MATERIAL_DOES_NOT_EXPIRE, the ValidTo parameter is invalid. You can also use the kms:ExpirationModel condition key to require the ExpirationModel parameter or a specific parameter value.

The following example policy statement allows a user to import key material into a CMK. The kms:ValidTo condition key limits the permission to ImportKeyMaterial requests where the ValidTo value is less than or equal to 1546257599.0 (December 31, 2018 11:59:59 PM).

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:ImportKeyMaterial",
  "Resource": "*",
  "Condition": {
    "NumericLessThanEquals": {
      "kms:ValidTo": "1546257599.0"
    }
  }
}

See Also

• kms:ExpirationModel

• kms:WrappingAlgorithm

• kms:WrappingKeySpec

kms:ViaService

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:ViaService	String	The kms:ViaService condition key is valid for all AWS KMS operations except: CreateKey, GenerateRandom, ListAliases, ListKeys, ListRetirableGrants, RetireGrant.	IAM and key policies

The kms:ViaService condition key limits use of an AWS KMS customer master key (CMK) to requests from specified AWS services. You can specify one or more services in each kms:ViaService condition key.

For example, the following statement from a key policy uses the kms:ViaService condition key to allow a customer managed CMK to be used for the specified actions only when the request comes from Amazon EC2 or Amazon RDS in the US West (Oregon) region on behalf of ExampleUser.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": [
    "kms:Encrypt",
    "kms:Decrypt",
    "kms:ReEncrypt*",
    "kms:GenerateDataKey*",
    "kms:CreateGrant",
    "kms:ListGrants",
    "kms:DescribeKey"
  ],
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:ViaService": [
        "ec2.us-west-2.amazonaws.com",
        "rds.us-west-2.amazonaws.com"
      ]
    }
  }
}

You can also use a kms:ViaService condition key to deny permission to use a CMK when the request comes from particular services. For example, the following policy statement from a key policy uses a kms:ViaService condition key to prevent a customer managed CMK from being used for Encrypt operations when the request comes from AWS Lambda on behalf of ExampleUser.

{
  "Effect": "Deny",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": [
    "kms:Encrypt"    
  ],
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:ViaService": [
        "lambda.us-west-2.amazonaws.com"        
      ]
    }
  }
}

Important

When you use the kms:ViaService condition key, the service makes the request on behalf of a principal in the AWS account. These principals must have the following permissions:

• Permission to use the CMK. The principal needs to grant these permissions to the integrated service so the service can use the customer managed CMK on behalf of the principal. For more information, see How AWS Services use AWS KMS.

• Permission to use the integrated service. For details about giving users access to an AWS service that integrates with AWS KMS, consult the documentation for the integrated service.

All AWS managed CMKs use a kms:ViaService condition key in their key policy document. This condition allows the CMK to be used only for requests that come from the service that created the CMK. To see the key policy for an AWS managed CMK, use the GetKeyPolicy operation.

The kms:ViaService condition key is valid in IAM and key policy statements. The services that you specify must be integrated with AWS KMS and support the kms:ViaService condition key.

The following table lists AWS services that are integrated with AWS KMS, support customer managed CMKs, and support the use of the kms:ViaService condition key in customer managed CMKs. The services in this table might not be available in all regions.

Services that support the kms:ViaService condition key in customer managed CMKs

Service Name	KMS ViaService Name
AWS Backup	backup.AWS_region.amazonaws.com
Amazon Connect	connect.AWS_region.amazonaws.com
AWS Database Migration Service (AWS DMS)	dms.AWS_region.amazonaws.com
AWS Directory Service	directoryservice.AWS_region.amazonaws.com
Amazon EC2 Systems Manager	ssm.AWS_region.amazonaws.com
Amazon Elastic Block Store (Amazon EBS)	ec2.AWS_region.amazonaws.com (EBS only)
Amazon Elastic File System	elasticfilesystem.AWS_region.amazonaws.com
Amazon Elasticsearch Service	es.AWS_region.amazonaws.com
Amazon FSx	fsx.AWS_region.amazonaws.com
AWS Glue	glue.AWS_region.amazonaws.com
Amazon Kinesis	kinesis.AWS_region.amazonaws.com
Amazon Kinesis Video Streams	kinesisvideo.AWS_region.amazonaws.com
AWS Lambda	lambda.AWS_region.amazonaws.com
Amazon Lex	lex.AWS_region.amazonaws.com
Amazon Managed Streaming for Kafka	kafka.AWS_region.amazonaws.com
Amazon Neptune	rds.AWS_region.amazonaws.com
Amazon Redshift	redshift.AWS_region.amazonaws.com
Amazon Relational Database Service (Amazon RDS)	rds.AWS_region.amazonaws.com
Amazon RDS Performance Insights	rds.AWS_region.amazonaws.com
AWS Secrets Manager (Secrets Manager)	secretsmanager.AWS_region.amazonaws.com
Amazon Simple Email Service (Amazon SES)	ses.AWS_region.amazonaws.com
Amazon Simple Notification Service (Amazon SNS)	sns.AWS_region.amazonaws.com
Amazon Simple Storage Service (Amazon S3)	s3.AWS_region.amazonaws.com
AWS Snowball	importexport.AWS_region.amazonaws.com
Amazon SQS	sqs.AWS_region.amazonaws.com
Amazon WorkMail	workmail.AWS_region.amazonaws.com
Amazon WorkSpaces	workspaces.AWS_region.amazonaws.com
AWS X-Ray	xray.AWS_region.amazonaws.com

kms:WrappingAlgorithm

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:WrappingAlgorithm	String	GetParametersForImport	IAM and key policies

This condition key controls access to the GetParametersForImport operation based on the value of the WrappingAlgorithm parameter in the request. You can use this condition to require principals to use a particular algorithm to encrypt key material during the import process. Requests for the required public key and import token fail when they specify a different wrapping algorithm.

The following example policy statement uses the kms:WrappingAlgorithm condition key to give the example user permission to call the GetParametersForImport operation, but prevents them from using the RSAES_OAEP_SHA_1 wrapping algorithm. When the WrappingAlgorithm in the GetParametersForImport request is RSAES_OAEP_SHA_1, the operation fails.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:GetParametersForImport",
  "Resource": "*",
  "Condition": {
    "StringNotEquals": {
      "kms:WrappingAlgorithm": "RSAES_OAEP_SHA_1"
    }
  }
}

See Also

• kms:ExpirationModel

• kms:ValidTo

• kms:WrappingKeySpec

kms:WrappingKeySpec

AWS KMS Condition Keys	Condition Type	API Operations	Policy Type
kms:WrappingKeySpec	String	GetParametersForImport	IAM and key policies

This condition key controls access to the GetParametersForImport operation based on the value of the WrappingKeySpec parameter in the request. You can use this condition to require principals to use a particular type of public key during the import process. If the request specifies a different key type, it fails.

Because the only valid value for the WrappingKeySpec parameter value is RSA_2048, preventing users from using this value effectively prevents them from using the GetParametersForImport operation.

The following example policy statement uses the kms:WrappingAlgorithm condition key to require that the WrappingKeySpec in the request is RSA_2048.

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::111122223333:user/ExampleUser"
  },
  "Action": "kms:GetParametersForImport",
  "Resource": "*",
  "Condition": {
    "StringEquals": {
      "kms:WrappingKeySpec": "RSA_2048"
    }
  }
}

See Also

• kms:ExpirationModel

• kms:ValidTo

• kms:WrappingAlgorithm