Merge pull request #256 from Plume-org/verify-signature

Verify activity's signature

plume-common/src/activity_pub/mod.rs

@@ -2,8 +2,7 @@ use activitypub::{Activity, Actor, Object, Link};
 use array_tool::vec::Uniq;
 use reqwest::Client;
 use rocket::{
-    Outcome,
-    http::Status,
+    Outcome, http::Status,
     response::{Response, Responder},
     request::{FromRequest, Request}
 };
@@ -104,11 +103,12 @@ pub fn broadcast<S: sign::Signer, A: Activity, T: inbox::WithInbox + Actor>(send
 
     for inbox in boxes {
         // TODO: run it in Sidekiq or something like that
+        let mut headers = request::headers();
+        headers.set(request::Digest::digest(signed.to_string()));
         let res = Client::new()
             .post(&inbox[..])
-            .headers(request::headers())
-            .header(request::signature(sender, request::headers()))
-            .header(request::digest(signed.to_string()))
+            .headers(headers.clone())
+            .header(request::signature(sender, headers))
             .body(signed.to_string())
             .send();
         match res {

plume-common/src/activity_pub/request.rs

@@ -4,6 +4,7 @@ use reqwest::{
     mime::Mime,
     header::{Accept, Date, Headers, UserAgent, qitem}
 };
+use std::ops::Deref;
 use std::time::SystemTime;
 
 use activity_pub::ap_accept_header;
@@ -19,6 +20,48 @@ header! {
     (Digest, "Digest") => [String]
 }
 
+impl Digest {
+    pub fn digest(body: String) -> Self {
+        let mut hasher = Hasher::new(MessageDigest::sha256()).unwrap();
+        hasher.update(&body.into_bytes()[..]).unwrap();
+        let res = base64::encode(&hasher.finish().unwrap());
+        Digest(format!("SHA-256={}", res))
+    }
+
+    pub fn verify(&self, body: String) -> bool {
+        if self.algorithm()=="SHA-256" {
+            let mut hasher = Hasher::new(MessageDigest::sha256()).unwrap();
+            hasher.update(&body.into_bytes()).unwrap();
+            self.value().deref()==hasher.finish().unwrap().deref()
+        } else {
+            false //algorithm not supported
+        }
+    }
+
+    pub fn algorithm(&self) -> &str {
+        let pos = self.0.find('=').unwrap();
+        &self.0[..pos]
+    }
+
+    pub fn value(&self) -> Vec<u8> {
+        let pos = self.0.find('=').unwrap()+1;
+        base64::decode(&self.0[pos..]).unwrap()
+    }
+
+    pub fn from_header(dig: &str) -> Result<Self, ()> {
+        if let Some(pos) = dig.find('=') {
+            let pos = pos+1;
+            if let Ok(_) = base64::decode(&dig[pos..]) {
+                Ok(Digest(dig.to_owned()))
+            } else {
+                Err(())
+            }
+        } else {
+            Err(())
+        }
+    }
+}
+
 pub fn headers() -> Headers {
     let mut headers = Headers::new();
     headers.set(UserAgent::new(USER_AGENT));
@@ -41,10 +84,3 @@ pub fn signature<S: Signer>(signer: &S, headers: Headers) -> Signature {
         signature = sign
     ))
 }
-
-pub fn digest(body: String) -> Digest {
-    let mut hasher = Hasher::new(MessageDigest::sha256()).unwrap();
-    hasher.update(&body.into_bytes()[..]).unwrap();
-    let res = base64::encode(&hasher.finish().unwrap());
-    Digest(format!("SHA-256={}", res))
-}

plume-common/src/activity_pub/sign.rs

@@ -6,6 +6,8 @@ use openssl::{
     rsa::Rsa,
     sha::sha256
 };
+use super::request;
+use rocket::http::HeaderMap;
 use serde_json;
 
 /// Returns (public key, private key)
@@ -20,10 +22,13 @@ pub trait Signer {
     
     /// Sign some data with the signer keypair
     fn sign(&self, to_sign: String) -> Vec<u8>;
+    /// Verify if the signature is valid
+    fn verify(&self, data: String, signature: Vec<u8>) -> bool;
 }
 
 pub trait Signable {
     fn sign<T>(&mut self, creator: &T) -> &mut Self where T: Signer;
+    fn verify<T>(self, creator: &T) -> bool where T: Signer;
 
     fn hash(data: String) -> String {
         let bytes = data.into_bytes();
@@ -53,4 +58,86 @@ impl Signable for serde_json::Value {
         self["signature"] = options;
         self
     }
+
+    fn verify<T: Signer>(mut self, creator: &T) -> bool {
+        let signature_obj = if let Some(sig) = self.as_object_mut().and_then(|o| o.remove("signature")) {
+            sig
+        } else {
+            //signature not present
+            return false
+        };
+        let signature = if let Ok(sig) = base64::decode(&signature_obj["signatureValue"].as_str().unwrap_or("")) {
+            sig
+        } else {
+            return false
+        };
+        let creation_date = &signature_obj["created"];
+        let options_hash  = Self::hash(json!({
+            "@context": "https://w3id.org/identity/v1",
+            "created": creation_date
+        }).to_string());
+        let document_hash = Self::hash(self.to_string());
+        let to_be_signed = options_hash + &document_hash;
+        creator.verify(to_be_signed, signature)
+    }
+}
+
+#[derive(Debug,Copy,Clone,PartialEq)]
+pub enum SignatureValidity {
+    Invalid,
+    ValidNoDigest,
+    Valid,
+    Absent,
+}
+
+impl SignatureValidity {
+    pub fn is_secure(&self) -> bool {
+        self==&SignatureValidity::Valid
+    }
+}
+
+pub fn verify_http_headers<S: Signer+::std::fmt::Debug>(sender: &S, all_headers: HeaderMap, data: String) -> SignatureValidity{
+    let sig_header = all_headers.get_one("Signature");
+    if sig_header.is_none() {
+        return SignatureValidity::Absent
+    }
+    let sig_header = sig_header.unwrap();
+
+    let mut _key_id = None;
+    let mut _algorithm = None;
+    let mut headers = None;
+    let mut signature = None;
+    for part in sig_header.split(',') {
+        match part {
+            part if part.starts_with("keyId=") => _key_id = Some(&part[7..part.len()-1]),
+            part if part.starts_with("algorithm=") => _algorithm = Some(&part[11..part.len()-1]),
+            part if part.starts_with("headers=") => headers = Some(&part[9..part.len()-1]),
+            part if part.starts_with("signature=") => signature = Some(&part[11..part.len()-1]),
+            _ => {},
+        }
+    }
+
+    if signature.is_none() || headers.is_none() {//missing part of the header
+        return SignatureValidity::Invalid
+    }
+    let headers = headers.unwrap().split_whitespace().collect::<Vec<_>>();
+    let signature = signature.unwrap();
+    let h = headers.iter()
+        .map(|header| (header,all_headers.get_one(header)))
+        .map(|(header, value)| format!("{}: {}", header.to_lowercase(), value.unwrap_or("")))
+        .collect::<Vec<_>>().join("\n");
+
+    if !sender.verify(h, base64::decode(signature).unwrap_or(Vec::new())) {
+        return SignatureValidity::Invalid
+    }
+    if !headers.contains(&"digest") {// signature is valid, but body content is not verified
+        return SignatureValidity::ValidNoDigest
+    }
+    let digest = all_headers.get_one("digest").unwrap_or("");
+    let digest = request::Digest::from_header(digest);
+    if !digest.map(|d| d.verify(data)).unwrap_or(false) {// signature was valid, but body content does not match its digest
+        SignatureValidity::Invalid
+    } else {
+	    SignatureValidity::Valid// all check passed
+    }
 }