diff --git a/README.md b/README.md
index ddc3a08..d0944f8 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,12 @@
 # digital-signature
 Repo for public checking digital signature of my files.
+
+Hello everyone!
+For checking digital sign on my files feel free to use this simple shell script.
+
+1. Download Invoice and their .signature file from email
+2. Run script with filename-of-invoice-file
+
+```
+./check-sign-file.sh <filename> [filename.signature] [public-keyfile]
+```
diff --git a/check-sign-file.sh b/check-sign-file.sh
new file mode 100755
index 0000000..b3d112e
--- /dev/null
+++ b/check-sign-file.sh
@@ -0,0 +1,51 @@
+#!/bin/bash
+
+RED='\033[0;31m'
+GRN='\033[1;32m'
+YEL='\033[0;33m'
+BLU='\033[1;34m'
+END='\033[0m' # No Color
+
+
+filename=$1
+sign=${2:-"$filename.signature"}
+
+
+date=$(date -I)
+
+if [ $# -eq 0 ]
+  then
+    echo "Usage: ./check-sign-file.sh <filename> [filename.signature] [public-keyfile]"
+    exit 1
+fi
+
+if [ ! -f $sign ]; then
+    printf $RED"Sign file not found!\n"$END
+    exit 1
+fi
+
+echo "Getting Aleksei Krugliak publickey..."
+curl https://raw.githubusercontent.com/ksemele/digital-signature/main/akrugliak-publickey.pem > akrugliak-publickey.pem
+echo "[$date] successfully get key"
+
+public_key=akrugliak-publickey.pem
+
+echo "Verifiying file [$filename] signed by [$public_key] sign-file [$sign]"
+
+printf $BLU
+echo "openssl dgst -sha256 -verify $public_key -signature $sign $filename"
+echo ""
+printf $END
+
+result=$(openssl dgst -sha256 -verify $public_key -signature $sign $filename | awk '{print $2}')
+
+if [ $result == "Failure" ]; then
+    printf $RED"Verifiying file [$filename]: $result\n"$END 
+else
+    printf $GRN"Verifiying file [$filename]: $result\n"$END 
+fi
+
+echo ""
+echo "rm -rf akrugliak-publickey.pem"
+rm -rf akrugliak-publickey.pem
+printf $GRN"done.\n"$END