Cloudimage - Documentation

URL sealing

To prevent your customer to remove certain parameters, you can seal them. For example, if you don't want you user to get the image without a watermark or a certain filter, you can use the URL sealing feature. This system is similar to the URL signature feature but it is only sealing the ci_eqs parameters and allows you to add more filters and operations. This method is compatible with the JS responsive plugin.

The signature is calculated as follows:

Signature = sha1('URI' + 'ci_eqs' + 'Salt' ) where URI = original_image_url and ci_eqs = value of the content of ci_eqs query string

The syntax to process an image is:


The Salt string is a shared secret between you and Cloudimage and only you will be able to calculate the signature of your images.

Contact us to enable the sealing and set up the Salt for your company token.

Step 1 - encode the query string

To watermark an image at URL with query string wat=1&wat_url=, you need to first base64-encode the query sting:




Step 2 - create the signature

The signature has to be created by sha1-hashing the string 'URI' + 'ci_eqs' + 'Salt':

sha1('' + 'd2F0PTEmd2F0X3VybD1odHRwOi8vc2FtcGxlLmxpL2xvdWlzLXZ1aXR0b24tbG9nby13aGl0ZS5wbmcmd2F0X3NjYWxlPTQ1JndhdF9ncmF2aXR5PXNvdXRod2VzdCZ3YXRfcGFkPTE1' + 'salt')

The final signature is:


Step 3 - construct the URL


The final URL becomes:

Step 4 - usage

You can use the URL as is or append more parameters to the query string:

Any parameters which are included in the sealed portion cannot be overwritten in the url. For example, if a watermark is activated with wat=1 and sealed, appending wat=0 in the url will not remove the watermark: