Additional capabilities in the ZTP provisioning file

The following optional capabilities of the provisioning file are supported for both ZTP and SZTP:

checksum for file download
SHA256 and MD5 are supported. The hash algorithm and hash value can be specifically configured for the file as shown in the following example. The file checksum is checked against the hash algorithm and hash value.
```
# List of Configuration Files to download
config "$(BOOT-PATH)/somefile.txt" {
 primary-url "$(FILESERVER)/somefile.txt"
        verification {
                hash-algorithm sha256
                          hash-value
"53473e2727caf55f3a38fa466622af2147762e26a8587e9248240a572cdee849"
        }
}
```

file encryption using AES256

When a file is downloaded and if the file has the encrypt keyword enabled in the provisioning file, the file is encrypted using AES256 and placed on the CF. This is useful when downloading certificates, keys, and trust anchors for TLS. The following example shows an excerpt from the provisioning file. In this example, in the certificate import the keyword encrypt is used to encrypt each file on the CF after the file was downloaded. In addition, the checksum is calculated on each file and checked to ensure the files are downloaded without errors.


import {
    client {
         cert "$(CERT-PATH)/device.crt" {
             primary-url "$(FILESERVER)/device.crt"
                 encrypt
                    verification {
                        hash-algorithm sha256
                            hash-value
"53473e2727caf55f3a38fa466622af2147762e26a8587e9248240a572cdee849"
                                 }
           }
           key "$(CERT-PATH)/device.key" {
              format pem
              primary-url "$(FILESERVER)/device.key"
                       encrypt
                       verification {
                          hash-algorithm sha256
                                 hash-value
"53473e2727caf55f3a38fa466622af2147762e26a8587e9248240a572cdee849"
                       }
    }
}
trust-anchor "NokiaSvcs" {
    cert "$(CERT-PATH)/owner-ca.crt" {
        format pem
        primary-url "$(FILESERVER)/owner-ca.crt"
                 encrypt
                  verification {
                      hash-algorithm sha256
                             hash-value
"53473e2727caf55f3a38fa466622af2147762e26a8587e9248240a572cdee849"
              }
    }
    crl "$(CERT-PATH)/owner-ca.crl"
    format der
    primary-url "$(FILESERVER)/owner-ca.crl"
             encrypt
              verification {
               hash-algorithm sha256
                    hash-value
"53473e2727caf55f3a38fa466622af2147762e26a8587e9248240a572cdee849"
              }
     }
    }
}

downloading the image files in ZIP file format
The files can be downloaded using the provisioning file with an optional checksum. The ZIP file is automatically unzipped and each individual file is placed on the CF. The checksum is checked across the entire ZIP file before it is unzipped.

Note: The specified directory path must end with a forward slash (/).
```
image "$(BOOT-PATH)/images.zip" {
  primary-url "$(FILESERVER)/images.zip"
     unzip {
       directory "cf3:/ztp/"
}
     verification {
             hash-algorithm sha256
       hash-value
"53473e2727caf55f3a38fa466622af2147762e26a8587e9248240a572cdee849"
        }
}
```
downloading a SHA256 or MD5 checksum file
The user can download a SHA256 or MD5 checksum file from Nokia servers for the ZIP image files. After the image file is unzipped, each *.tim file has its checksum checked against these checksum files.

The following are examples of checksum files.
```
17717f13ecf19179e367d990277e943993d53d771b44d19fddf5d349b1e7e7c4 cf3:/ztp/cpm.tim
616656b2224e65e29d71355ea41d9dc548c281e9f729c97fe46f3a5c643acb09 cf3:/ztp/iom.tim
dd9455158dc2dfbf937eb372bbef73ebab97f951efa742eec16a4ed4edd3ca9b cf3:/ztp/support.tim
```

Checksum or file decryption errors cause the failure of the ZTP or SZTP procedure, in which case the node generates an error and logs the event.