aws_kms_key.cloudtrail.tf

resource "aws_kms_key" "cloudtrail" {
  # checkov:skip=CKV_AWS_33: Key policy not iam policy
  enable_key_rotation = true

  policy = <<POLICY
{
    "Version": "2012-10-17",
    "Id": "Key policy created by CloudTrail",
    "Statement": [
        {
            "Sid": "Enable IAM User Permissions",
            "Effect": "Allow",
            "Principal": {
                "AWS": "arn:aws:iam::${data.aws_caller_identity.current.account_id}:root"
            },
            "Action": "kms:*",
            "Resource": "*"
        },
        {
            "Sid": "Allow CloudTrail to encrypt logs",
            "Effect": "Allow",
            "Principal": {
                "Service": "cloudtrail.amazonaws.com"
            },
            "Action": "kms:GenerateDataKey*",
            "Resource": "*",
            "Condition": {
                "StringLike": {
                    "kms:EncryptionContext:aws:cloudtrail:arn": "arn:aws:cloudtrail:*:${data.aws_caller_identity.current.account_id}:trail/*"
                }
            }
        },
        {
            "Sid": "Allow CloudTrail to describe key",
            "Effect": "Allow",
            "Principal": {
                "Service": "cloudtrail.amazonaws.com"
            },
            "Action": "kms:DescribeKey",
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Principal": {
                "Service": "logs.${data.aws_region.current.name}.amazonaws.com"
            },
            "Action": [
                "kms:Encrypt*",
                "kms:Decrypt*",
                "kms:ReEncrypt*",
                "kms:GenerateDataKey*",
                "kms:Describe*"
            ],
            "Resource": "*",
            "Condition": {
                "ArnEquals": {
                    "kms:EncryptionContext:aws:logs:arn": "arn:aws:logs:${data.aws_region.current.name}:${data.aws_caller_identity.current.account_id}:log-group:${var.log_group_name}"
                }
            }
        },
        {
            "Sid": "Allow principals in the account to decrypt log files",
            "Effect": "Allow",
            "Principal": {
                "AWS": "*"
            },
            "Action": [
                "kms:Decrypt",
                "kms:ReEncryptFrom"
            ],
            "Resource": "*",
            "Condition": {
                "StringEquals": {
                    "kms:CallerAccount": "${data.aws_caller_identity.current.account_id}"
                },
                "StringLike": {
                    "kms:EncryptionContext:aws:cloudtrail:arn": "arn:aws:cloudtrail:*:${data.aws_caller_identity.current.account_id}:trail/*"
                }
            }
        },
        {
            "Sid": "Allow alias creation during setup",
            "Effect": "Allow",
            "Principal": {
                "AWS": "*"
            },
            "Action": "kms:CreateAlias",
            "Resource": "*",
            "Condition": {
                "StringEquals": {
                    "kms:ViaService": "ec2.us-west-2.amazonaws.com",
                    "kms:CallerAccount": "${data.aws_caller_identity.current.account_id}"
                }
            }
        },
        {
            "Sid": "Enable cross account log decryption",
            "Effect": "Allow",
            "Principal": {
                "AWS": "*"
            },
            "Action": [
                "kms:Decrypt",
                "kms:ReEncryptFrom"
            ],
            "Resource": "*",
            "Condition": {
                "StringEquals": {
                    "kms:CallerAccount": "${data.aws_caller_identity.current.account_id}"
                },
                "StringLike": {
                    "kms:EncryptionContext:aws:cloudtrail:arn": "arn:aws:cloudtrail:*:${data.aws_caller_identity.current.account_id}:trail/*"
                }
            }
        }
    ]
}
POLICY
}



resource "aws_kms_alias" "trails" {
  name          = "alias/cloudtrail"
  target_key_id = aws_kms_key.cloudtrail.key_id
}