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:

//token.cloudimg.io/v7/original_image_url?ci_eqs=Sealed_parameters&ci_seal=Signature

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 sample.li/birds.jpg with query string wat=1&wat_url=http://sample.li/louis-vuitton-logo-white.png&wat_scale=45&wat_gravity=southwest&wat_pad=15, you need to first base64-encode the query sting:

base64('wat=1&wat_url=http://sample.li/louis-vuitton-logo-white.png&wat_scale=45&wat_gravity=southwest&wat_pad=15')

becomes

d2F0PTEmd2F0X3VybD1odHRwOi8vc2FtcGxlLmxpL2xvdWlzLXZ1aXR0b24tbG9nby13aGl0ZS5wbmcmd2F0X3NjYWxlPTQ1JndhdF9ncmF2aXR5PXNvdXRod2VzdCZ3YXRfcGFkPTE1

Step 2 - create the signature

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

sha1('sample.li/birds.jpg' + 'd2F0PTEmd2F0X3VybD1odHRwOi8vc2FtcGxlLmxpL2xvdWlzLXZ1aXR0b24tbG9nby13aGl0ZS5wbmcmd2F0X3NjYWxlPTQ1JndhdF9ncmF2aXR5PXNvdXRod2VzdCZ3YXRfcGFkPTE1' + 'salt')

The final signature is:

a355cce069fbfb18a4c39113067bf626ead2ebab

Step 3 - construct the URL

//token.cloudimg.io/v7/original_image_url?ci_eqs=Sealed_parameters&ci_seal=Signature

The final URL becomes:

https://demoseal.cloudimg.io/v7/sample.li/birds.jpg?ci_eqs=d2F0PTEmd2F0X3VybD1odHRwOi8vc2FtcGxlLmxpL2xvdWlzLXZ1aXR0b24tbG9nby13aGl0ZS5wbmcmd2F0X3NjYWxlPTQ1JndhdF9ncmF2aXR5PXNvdXRod2VzdCZ3YXRfcGFkPTE1&ci_seal=a355cce069fbfb18a4

Step 4 - usage

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

https://demoseal.cloudimg.io/v7/sample.li/birds.jpg?ci_eqs=d2F0PTEmd2F0X3VybD1odHRwOi8vc2FtcGxlLmxpL2xvdWlzLXZ1aXR0b24tbG9nby13aGl0ZS5wbmcmd2F0X3NjYWxlPTQ1JndhdF9ncmF2aXR5PXNvdXRod2VzdCZ3YXRfcGFkPTE1&ci_seal=a355cce069fbfb18a4&w=700&h=700

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:

https://demoseal.cloudimg.io/v7/sample.li/birds.jpg?ci_eqs=d2F0PTEmd2F0X3VybD1odHRwOi8vc2FtcGxlLmxpL2xvdWlzLXZ1aXR0b24tbG9nby13aGl0ZS5wbmcmd2F0X3NjYWxlPTQ1JndhdF9ncmF2aXR5PXNvdXRod2VzdCZ3YXRfcGFkPTE1&ci_seal=a355cce069fbfb18a4&wat=0