SHA 1 digest in apk file


I have used apktool to extract an apk file. There is a CERT.SF file in META INF folder and surprisingly there are lot of entries as following.

Name - xxxx

There are lots of entries in this kind of key-value pair (more than 100). In most of the cases text provided in Name field is not readable text and in other cases it is pointing to some metadata file as follows

Name - xxx/xxx/xxx/xx_metadata
SHA1-Digest: XXXXX…

Can u please help me out by suggesting any way forward ?