diff --git a/README.md b/README.md
new file mode 100644
index 0000000..f22e444
--- /dev/null
+++ b/README.md
@@ -0,0 +1,12 @@
+Gremlin
+=======
+
+This is small proof of concept to crack any PDF file encrypted with PESEL number as password.
+
+Before you run it please download all dependencies
+
+    go mod download
+
+To use it just run
+
+    go run main.go /PathFile/To/Pdf/File
diff --git a/algorithm/control_sum.go b/algorithm/control_sum.go
new file mode 100644
index 0000000..4e0879b
--- /dev/null
+++ b/algorithm/control_sum.go
@@ -0,0 +1,29 @@
+package algorithm
+
+import "strconv"
+
+func getLastDigit(number int) int {
+	strNumber := strconv.Itoa(number)
+	lastDigit := strNumber[len(strNumber)-1:]
+	result, _ := strconv.Atoi(lastDigit)
+	return result
+}
+
+func ControlSum(peselArr [10]int) int {
+	result := peselArr[0]*1 +
+		peselArr[1]*3 +
+		peselArr[2]*7 +
+		peselArr[3]*9 +
+		peselArr[4]*1 +
+		peselArr[5]*3 +
+		peselArr[6]*7 +
+		peselArr[7]*9 +
+		peselArr[8]*1 +
+		peselArr[9]*3
+	lastDigit := getLastDigit(result)
+	if lastDigit == 0 {
+		return 0
+	} else {
+		return 10 - getLastDigit(result%10)
+	}
+}
diff --git a/algorithm/decrypt.go b/algorithm/decrypt.go
new file mode 100644
index 0000000..564b64b
--- /dev/null
+++ b/algorithm/decrypt.go
@@ -0,0 +1,44 @@
+package algorithm
+
+import (
+	"fmt"
+	"os"
+	"sync"
+
+	"github.com/unidoc/unipdf/v3/model"
+)
+
+func DecryptPdf(filePath string, passChannel chan string, wg *sync.WaitGroup) error {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return err
+	}
+
+	defer f.Close()
+
+	pdfReader, err := model.NewPdfReader(f)
+	if err != nil {
+		return err
+	}
+
+	isEncrypted, err := pdfReader.IsEncrypted()
+	if err != nil {
+		return err
+	}
+
+	if isEncrypted {
+		for password := range passChannel {
+			auth, err := pdfReader.Decrypt([]byte(password))
+			if err != nil {
+				return err
+			}
+			if auth {
+				fmt.Println(password)
+				wg.Done()
+			} else {
+				fmt.Errorf("Wrong password")
+			}
+		}
+	}
+	return nil
+}
diff --git a/algorithm/generator.go b/algorithm/generator.go
new file mode 100644
index 0000000..0dc4833
--- /dev/null
+++ b/algorithm/generator.go
@@ -0,0 +1,30 @@
+package algorithm
+
+import (
+	"fmt"
+	"strconv"
+	"time"
+)
+
+func GeneratePeselsForDate(date time.Time, passChannel chan string) {
+	peselDate := date.Format("060102")
+	if date.Year() >= 2000 {
+		peselDate = peselDate[:2] + "2" + peselDate[3:]
+	}
+	for i := 0; i < 10000; i++ {
+		peselWithoutValidation := peselDate + fmt.Sprintf("%04d", i)
+		checksum := ControlSum(peselIntArray(peselWithoutValidation))
+		pesel := peselWithoutValidation + strconv.Itoa(checksum)
+		passChannel <- pesel
+	}
+	fmt.Println("Nothing found for: ", date)
+	close(passChannel)
+}
+
+func peselIntArray(pesel string) [10]int {
+	var peselArray [10]int
+	for idx, digit := range pesel {
+		peselArray[idx] = int(digit) - '0'
+	}
+	return peselArray
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..5997e00
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,22 @@
+module github.com/galuszkak/pesel
+
+go 1.17
+
+require github.com/unidoc/unipdf/v3 v3.32.0
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/konsorten/go-windows-terminal-sequences v1.0.2 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/sirupsen/logrus v1.5.0 // indirect
+	github.com/stretchr/testify v1.6.1 // indirect
+	github.com/unidoc/pkcs7 v0.1.0 // indirect
+	github.com/unidoc/timestamp v0.0.0-20200412005513-91597fd3793a // indirect
+	github.com/unidoc/unitype v0.2.1 // indirect
+	golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0 // indirect
+	golang.org/x/image v0.0.0-20211028202545-6944b10bf410 // indirect
+	golang.org/x/sys v0.0.0-20200413165638-669c56c373c4 // indirect
+	golang.org/x/text v0.3.6 // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..e78669e
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,58 @@
+github.com/adrg/strutil v0.1.0/go.mod h1:pXRr2+IyX5AEPAF5icj/EeTaiflPSD2hvGjnguilZgE=
+github.com/adrg/sysfont v0.1.1/go.mod h1:19nTHzfIn/HbngFMet+yNAvwSQYtOJYMI7vWexLWyNw=
+github.com/adrg/xdg v0.2.1/go.mod h1:ZuOshBmzV4Ta+s23hdfFZnBsdzmoR3US0d7ErpqSbTQ=
+github.com/boombuler/barcode v1.0.0/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/golang/snappy v0.0.4/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/konsorten/go-windows-terminal-sequences v1.0.2 h1:DB17ag19krx9CFsz4o3enTrPXyIXCl+2iCXH/aMAp9s=
+github.com/konsorten/go-windows-terminal-sequences v1.0.2/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/montanaflynn/stats v0.6.6/go.mod h1:etXPPgVO6n31NxCd9KQUMvCM+ve0ruNzt6R8Bnaayow=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.5.0 h1:1N5EYkVAPEywqZRJd7cwnRtCb6xJx7NH3T3WUTF980Q=
+github.com/sirupsen/logrus v1.5.0/go.mod h1:+F7Ogzej0PZc/94MaYx/nvG9jOFMD2osvC3s+Squfpo=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/trimmer-io/go-xmp v1.0.0/go.mod h1:Aaptr9sp1lLv7UnCAdQ+gSHZyY2miYaKmcNVj7HRBwA=
+github.com/unidoc/freetype v0.0.0-20220130190903-3efbeefd0c90/go.mod h1:mJ/Q7JnqEoWtajJVrV6S1InbRv0K/fJerPB5SQs32KI=
+github.com/unidoc/pkcs7 v0.0.0-20200411230602-d883fd70d1df/go.mod h1:UEzOZUEpJfDpywVJMUT8QiugqEZC29pDq7kdIZhWCr8=
+github.com/unidoc/pkcs7 v0.1.0 h1:9bQfbWMYsIfUP8PyhTcBudOsvbLpNH0MBv4U0P/jDTE=
+github.com/unidoc/pkcs7 v0.1.0/go.mod h1:UEzOZUEpJfDpywVJMUT8QiugqEZC29pDq7kdIZhWCr8=
+github.com/unidoc/timestamp v0.0.0-20200412005513-91597fd3793a h1:RLtvUhe4DsUDl66m7MJ8OqBjq8jpWBXPK6/RKtqeTkc=
+github.com/unidoc/timestamp v0.0.0-20200412005513-91597fd3793a/go.mod h1:j+qMWZVpZFTvDey3zxUkSgPJZEX33tDgU/QIA0IzCUw=
+github.com/unidoc/unipdf/v3 v3.32.0 h1:GpQAHDFpQJatXf/iH6ryP1J0GnwPyXhIFuIS219cg1o=
+github.com/unidoc/unipdf/v3 v3.32.0/go.mod h1:OUIt+FTxVqRJl3OFuqiPTPaxPwoYUjkmqPiRRh/SfLo=
+github.com/unidoc/unitype v0.2.1 h1:x0jMn7pB/tNrjEVjy3Ukpxo++HOBQaTCXcTYFA6BH3w=
+github.com/unidoc/unitype v0.2.1/go.mod h1:mafyug7zYmDOusqa7G0dJV45qp4b6TDAN+pHN7ZUIBU=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0 h1:hb9wdF1z5waM+dSIICn1l0DkLVDT3hqhhQsDNUmHPRE=
+golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/image v0.0.0-20211028202545-6944b10bf410 h1:hTftEOvwiOq2+O8k2D5/Q7COC7k5Qcrgc2TFURJYnvQ=
+golang.org/x/image v0.0.0-20211028202545-6944b10bf410/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200413165638-669c56c373c4 h1:opSr2sbRXk5X5/givKrrKj9HXxFpW2sdCiP8MJSKLQY=
+golang.org/x/sys v0.0.0-20200413165638-669c56c373c4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
+golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..f573969
--- /dev/null
+++ b/main.go
@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"sync"
+	"time"
+
+	"github.com/galuszkak/pesel/algorithm"
+)
+
+func main() {
+	channel := make(chan string)
+	wg := sync.WaitGroup{}
+	wg.Add(1)
+	if len(os.Args) != 2 {
+		fmt.Println("You need to provide path to PDF\nExample: go run main.go ./PIT.pdf ")
+		os.Exit(1)
+	}
+	filePath := os.Args[1]
+	// We are only interested in people older than 18 years
+	// So start date 2004/2/29
+	// Also we want to include people from 18 to 60 years = 42 years
+	// 365 days * 42years
+	startDate := time.Date(2004, time.February, 29, 0, 0, 0, 0, time.UTC)
+	allDays := 365 * 42
+	for i := 0; i < allDays; i++ {
+		go algorithm.GeneratePeselsForDate(startDate, channel)
+		go algorithm.DecryptPdf(filePath, channel, &wg)
+		startDate = startDate.AddDate(0, 0, -1)
+	}
+	wg.Wait()
+}