1 files changed, 78 insertions, 0 deletions
diff --git a/pwned.go b/pwned.go
new file mode 100644
index 0000000..a965c4d
--- /dev/null
+++ b/pwned.go
@@ -0,0 +1,78 @@
+package main
+
+// Adapted from https://github.com/lenartj/pwned-passwords
+import (
+	"crypto/sha1"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"sort"
+	"strings"
+)
+
+type pwdb struct {
+	f           *os.File
+	n           int
+	rs          int
+	hash_length int
+}
+
+func NewPWDB(fn string) (*pwdb, error) {
+	f, err := os.Open(fn)
+	if err != nil {
+		return nil, err
+	}
+
+	stat, err := f.Stat()
+	if err != nil {
+		return nil, err
+	}
+
+	const rs = 63 // V2 has fixed width of 63 bytes
+	if stat.Size()%rs != 0 {
+		return nil, fmt.Errorf("Unexpected password file format (must be a text file with 63 char width starting with sha1)")
+	}
+	const hash_length = 40 // sha1 is 40 chars
+
+	return &pwdb{f, int(stat.Size() / rs), rs, hash_length}, nil
+}
+
+func (db *pwdb) record(i int) string {
+	b := make([]byte, db.hash_length)
+	db.f.ReadAt(b, int64(i*db.rs))
+	return string(b)
+}
+
+func (db *pwdb) SearchHash(hash string) bool {
+	if len(hash) != db.hash_length {
+		return false
+	}
+	needle := strings.ToUpper(hash)
+
+	i := sort.Search(db.n, func(i int) bool {
+		return db.record(i) >= needle
+	})
+	return i < db.n && db.record(i) == needle
+}
+
+func (db *pwdb) SearchPassword(password string) bool {
+	h := sha1.New()
+	io.WriteString(h, password)
+	return db.SearchHash(fmt.Sprintf("%x", h.Sum(nil)))
+}
+
+func (db *pwdb) Close() {
+	db.f.Close()
+}
+
+func IsPasswordCompromised(password string) bool {
+	pwndDB, err := NewPWDB(pwman.PwnedDBFile)
+	if err != nil {
+		log.Println("ERROR", "pwnedb", err)
+		return false
+	}
+	defer pwndDB.Close()
+
+	return pwndDB.SearchPassword(password)
+}