update readme with improved usage

README.md

@@ -11,44 +11,29 @@ Bob opens a terminal and runs:
 
 It prints out the following message:
 
-    run this command to encrypt data: ./build/linux/amd64/secretshare AAAAB3NzaC1yc2EAAAADAQABAAABAQCwuaFN5PT7fd67c/FdPtjxmzN4ZpoT3nq832zpizoOJAJBSTRTIUltjeh2PTAlml9nKodPODvZxTw88w695vdoB7mpLUfCKXKKtI/9DV8Ay7NJKoiQK9hwofgaPXBfSMfp5veMEw8iD3OKqkFdBbYryxwUhhGICktUuUaQHpQVVuHNjlbRoVBxnb8mp4apP2B627ARBCqyRXz00pY2u9zk96GLbpaNvE7ON50G0BG4qb9iy+09hWtMC8unncSw4AT+/Oihwe1/sVdvQunWj/27rnPHbrzCplkUO+59HXYhE/LUypbzSGGVyAOsBVeWcdg3v1oXmb9LaaXh8HDb2Od7
+    To decrypt data, run: ./build/linux/amd64/secretshare decrypt < file_to_decrypt
+    To encrypt data, run: ./build/linux/amd64/secretshare <encryption_key> < data_to_encrypt
+
+    For example if someone wanted to send you data, they would run:
+    ./build/linux/amd64/secretshare AAAAB3NzaC1yc2EAAAADAQABAAABAQCkSAXQqyy+99uJGaYy6dBVNITdTrYeNewigGhx6/SrPppJX7KLPo6qSI8vP/ej8VDiFJGB4FjbiCLarkn1X1e1F4GW7CkjylUmD1X7njl6EeuZSzqvzsWoyO3Pgwa94d/mkQNvfvGyC9FopJh0pdVbLcPuyX75Tc6SmD8jq9PifoyC3nX2qeUOSZMgjbADpsIGABENaaDs1gTeRp2KwYHG2UwxnAUNKoANFIUK1McAL37xSJJ32pY4vEtlYxzhu2Rji7fUvQB4gqWhKuoOOoP1aP4zcOSPORMyZyPOPLT3SiVnW4GI10j0p73Y/aoYeg0eRUvhKB8WDRwOXIldgWrv
 
-Then waits for bob to enter an encypted message via the prompt:
+Bob replies to Alice and tells her she can send him data using:
 
-    enter encrypted data
+    ./build/linux/amd64/secretshare AAAAB3NzaC1yc2EAAAADAQABAAABAQCkSAXQqyy+99uJGaYy6dBVNITdTrYeNewigGhx6/SrPppJX7KLPo6qSI8vP/ej8VDiFJGB4FjbiCLarkn1X1e1F4GW7CkjylUmD1X7njl6EeuZSzqvzsWoyO3Pgwa94d/mkQNvfvGyC9FopJh0pdVbLcPuyX75Tc6SmD8jq9PifoyC3nX2qeUOSZMgjbADpsIGABENaaDs1gTeRp2KwYHG2UwxnAUNKoANFIUK1McAL37xSJJ32pY4vEtlYxzhu2Rji7fUvQB4gqWhKuoOOoP1aP4zcOSPORMyZyPOPLT3SiVnW4GI10j0p73Y/aoYeg0eRUvhKB8WDRwOXIldgWrv
 
-Bob carefully leaves his terminal running (if he were to quit it, he would no longer be able to decode the data).
-Bob sends the message to alice over slack:
+Alice then runs the command:
 
-    Hey Alice, you can send me a secret using secretshare by running it like:
-    ./build/linux/amd64/secretshare AAAAB3NzaC1yc2EAAAADAQABAAABAQCwuaFN5PT7fd67c/FdPtjxmzN4ZpoT3nq832zpizoOJAJBSTRTIUltjeh2PTAlml9nKodPODvZxTw88w695vdoB7mpLUfCKXKKtI/9DV8Ay7NJKoiQK9hwofgaPXBfSMfp5veMEw8iD3OKqkFdBbYryxwUhhGICktUuUaQHpQVVuHNjlbRoVBxnb8mp4apP2B627ARBCqyRXz00pY2u9zk96GLbpaNvE7ON50G0BG4qb9iy+09hWtMC8unncSw4AT+/Oihwe1/sVdvQunWj/27rnPHbrzCplkUO+59HXYhE/LUypbzSGGVyAOsBVeWcdg3v1oXmb9LaaXh8HDb2Od7
+    echo "Here's your new password. Dont share it with anyone. I hope nobody decrypts this message. anyway it's "querty". Have fun." | ./build/linux/amd64/secretshare AAAAB3NzaC1yc2EAAAADAQABAAABAQCkSAXQqyy+99uJGaYy6dBVNITdTrYeNewigGhx6/SrPppJX7KLPo6qSI8vP/ej8VDiFJGB4FjbiCLarkn1X1e1F4GW7CkjylUmD1X7njl6EeuZSzqvzsWoyO3Pgwa94d/mkQNvfvGyC9FopJh0pdVbLcPuyX75Tc6SmD8jq9PifoyC3nX2qeUOSZMgjbADpsIGABENaaDs1gTeRp2KwYHG2UwxnAUNKoANFIUK1McAL37xSJJ32pY4vEtlYxzhu2Rji7fUvQB4gqWhKuoOOoP1aP4zcOSPORMyZyPOPLT3SiVnW4GI10j0p73Y/aoYeg0eRUvhKB8WDRwOXIldgWrv
 
+Which outputs:
 
-Alice then Runs the above command and sees:
+    DpNw53fz1c2TUVwXTO/K2w5CYPvARTVzjzQb/9Rdt8+lW7tfFy8t9BWqdwN2vq7lwMjkqmKxJIKDhc8OwMh+TkMrmC4Q0Qr146td9E9vu+XV5LyBD7OlYXqFo0edE9QmyrRCcG9teV3XuLpmO7XgnenYnyOTySepjHX1rZgff6VVGn1dWtHLKk32H6D39q+HkY+8k+cTUgXwWe3rJTcjipXJAsDmH9/DoPJcCwH/Rc/9mz+zJW9YEiASuxl37e639erSFY3JwTTTOfnBzOoS4pWJPQtpCNdx77RXlSbNPyx+CgBMLpx5/QgqyLcBe0mWf2pA17eYHN3Z6gDt3Wsavg==
 
-    enter data to encrypt
+She sends this encrypted data to Bob, who runs the following command to decrypt it:
 
-She enters the following data:
 
-    Here's your new password. Dont share it with anyone. I hope nobody decrypts this message. anyway it's "querty". Have fun.
+    echo "DpNw53fz1c2TUVwXTO/K2w5CYPvARTVzjzQb/9Rdt8+lW7tfFy8t9BWqdwN2vq7lwMjkqmKxJIKDhc8OwMh+TkMrmC4Q0Qr146td9E9vu+XV5LyBD7OlYXqFo0edE9QmyrRCcG9teV3XuLpmO7XgnenYnyOTySepjHX1rZgff6VVGn1dWtHLKk32H6D39q+HkY+8k+cTUgXwWe3rJTcjipXJAsDmH9/DoPJcCwH/Rc/9mz+zJW9YEiASuxl37e639erSFY3JwTTTOfnBzOoS4pWJPQtpCNdx77RXlSbNPyx+CgBMLpx5/QgqyLcBe0mWf2pA17eYHN3Z6gDt3Wsavg==" | ./build/linux/amd64/secretshare decrypt
 
-The program then outputs:
+Which outputs:
 
-    --- Below is the encrypted data ---
-
-    ptIDqdJTgu6SITIsWV/fM93RgkEeEn0TzAtZKy/sAo7I5SEwJ0UjrPCbZJNPX1skRRbUIUElNWepX37KG71zJfk41/bKg5q/PLq8bL5ZiGg4+PXld4zuPGZZShUJRWcL2+2/JQBi6qsvej1E2I1mf8EGkEd/rmnlFAoqxOgxCz7Y8Uu6RgP97PTvJQNFWyJEkNnAizb+RyXZyoQaTaZnSOr85DUdKSuOYEj6RLVLmpckTK6130NycMZlK5MjTWtzWlrmy45T1YXSxyrAPpnXjcWSxD6l0qbDCnflGmHaJ6CBtBnb8aYiCDFufzbGqW11ZGZaA/2GXvDjm5WFankLsA==
-
-She sends this data to Bob, which copies and pastes the data into his terminal which was left running the sharesecret tool:
-
-    enter encrypted data
-    ptIDqdJTgu6SITIsWV/fM93RgkEeEn0TzAtZKy/sAo7I5SEwJ0UjrPCbZJNPX1skRRbUIUElNWepX37KG71zJfk41/bKg5q/PLq8bL5ZiGg4+PXld4zuPGZZShUJRWcL2+2/JQBi6qsvej1E2I1mf8EGkEd/rmnlFAoqxOgxCz7Y8Uu6RgP97PTvJQNFWyJEkNnAizb+RyXZyoQaTaZnSOr85DUdKSuOYEj6RLVLmpckTK6130NycMZlK5MjTWtzWlrmy45T1YXSxyrAPpnXjcWSxD6l0qbDCnflGmHaJ6CBtBnb8aYiCDFufzbGqW11ZGZaA/2GXvDjm5WFankLsA==
-
-It then prints out the decrypted message:
-
-    -- start of message --
-    Here's your new password. Dont share it with anyone. I hope nobody decrypts this message. anyway it's "querty". Have fun.
-
-    -- end of message --
-    press ctrl-c to quit, or continue decoding more messages.
-
-And there you have it!
+    Here's your new password. Dont share it with anyone. I hope nobody decrypts this message. anyway it's querty. Have fun.

main.go

@@ -169,30 +169,40 @@ func genOrLoadKeys() (string, string, error) {
 
 func main() {
 	test()
-	if len(os.Args) > 1 {
-		encryptMain(os.Args[1])
+	pub, priv, err := genOrLoadKeys()
+	pub = strings.TrimPrefix(pub, "ssh-rsa ")
+
+	if len(os.Args) <= 1 {
+		appName := "secret-share"
+		if len(os.Args) > 0 {
+			appName = os.Args[0]
+		}
+		fmt.Printf("To decrypt data, run: %s decrypt < file_to_decrypt\n", appName)
+		fmt.Printf("To encrypt data, run: %s <encryption_key> < data_to_encrypt\n", appName)
+		fmt.Printf("\n")
+		fmt.Printf("For example if someone wanted to send you data, they would run:\n%s %s < data_to_encrypt\n", appName, pub)
 		return
 	}
 
-	pub, priv, err := genOrLoadKeys()
+	arg := os.Args[1]
+
+	data, err := ioutil.ReadAll(os.Stdin)
 	if err != nil {
 		panic(err)
 	}
-	pub = strings.TrimPrefix(pub, "ssh-rsa ")
 
-	fmt.Printf("run this command to encrypt data: %s %s\n", os.Args[0], pub)
-
-	for {
-		data := promptLine("enter encrypted data")
-		data2, err := decrypt(data, priv)
+	if arg == "decrypt" {
+		data2, err := decrypt(string(data), priv)
 		if err != nil {
-			fmt.Printf("failed to decrypt: %v\n", err)
-			continue
+			panic(err)
 		}
-		fmt.Println("")
-		fmt.Println("-- start of message --")
 		fmt.Println(data2)
-		fmt.Println("-- end of message --")
-		fmt.Println("press ctrl-c to quit, or continue decoding more messages.")
+		return
 	}
+
+	encrypted, err := encrypt(string(data), "ssh-rsa "+arg)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(encrypted)
 }