feat: Add support for DynamicAssertions in JSON format

cawg_identity/src/builder/identity_assertion_builder.rs

@@ -12,7 +12,7 @@
 // each license.
 
 use async_trait::async_trait;
-use c2pa::{AsyncDynamicAssertion, DynamicAssertion, PreliminaryClaim};
+use c2pa::{AsyncDynamicAssertion, DynamicAssertion, DynamicAssertionContent, PreliminaryClaim};
 use serde_bytes::ByteBuf;
 
 use super::{CredentialHolder, IdentityBuilderError};
@@ -50,8 +50,8 @@ impl DynamicAssertion for IdentityAssertionBuilder {
         "cawg.identity".to_string()
     }
 
-    fn reserve_size(&self) -> usize {
-        self.credential_holder.reserve_size()
+    fn reserve_size(&self) -> c2pa::Result<usize> {
+        Ok(self.credential_holder.reserve_size())
         // TO DO: Credential holder will state reserve size for signature.
         // Add additional size for CBOR wrapper outside signature.
     }
@@ -61,7 +61,7 @@ impl DynamicAssertion for IdentityAssertionBuilder {
         _label: &str,
         size: Option<usize>,
         claim: &PreliminaryClaim,
-    ) -> c2pa::Result<Vec<u8>> {
+    ) -> c2pa::Result<DynamicAssertionContent> {
         // TO DO: Better filter for referenced assertions.
         // For now, just require hard binding.
 
@@ -120,8 +120,8 @@ impl AsyncDynamicAssertion for AsyncIdentityAssertionBuilder {
         "cawg.identity".to_string()
     }
 
-    fn reserve_size(&self) -> usize {
-        self.credential_holder.reserve_size()
+    fn reserve_size(&self) -> c2pa::Result<usize> {
+        Ok(self.credential_holder.reserve_size())
         // TO DO: Credential holder will state reserve size for signature.
         // Add additional size for CBOR wrapper outside signature.
     }
@@ -131,7 +131,7 @@ impl AsyncDynamicAssertion for AsyncIdentityAssertionBuilder {
         _label: &str,
         size: Option<usize>,
         claim: &PreliminaryClaim,
-    ) -> c2pa::Result<Vec<u8>> {
+    ) -> c2pa::Result<DynamicAssertionContent> {
         // TO DO: Better filter for referenced assertions.
         // For now, just require hard binding.
 
@@ -158,7 +158,7 @@ fn finalize_identity_assertion(
     signer_payload: SignerPayload,
     size: Option<usize>,
     signature_result: Result<Vec<u8>, IdentityBuilderError>,
-) -> c2pa::Result<Vec<u8>> {
+) -> c2pa::Result<DynamicAssertionContent> {
     // TO DO: Think through how errors map into c2pa::Error.
     let signature = signature_result.map_err(|e| c2pa::Error::BadParam(e.to_string()))?;
 
@@ -202,5 +202,5 @@ fn finalize_identity_assertion(
         assert_eq!(assertion_size, assertion_cbor.len());
     }
 
-    Ok(assertion_cbor)
+    Ok(DynamicAssertionContent::Cbor(assertion_cbor))
 }

sdk/src/dynamic_assertion.rs

@@ -19,6 +19,18 @@ use async_trait::async_trait;
 
 use crate::{hashed_uri::HashedUri, Result};
 
+/// The type of content that can be returned by a [`DynamicAssertion`] content call.
+pub enum DynamicAssertionContent {
+    /// The assertion is a CBOR-encoded binary blob.
+    Cbor(Vec<u8>),
+
+    /// The assertion is a JSON-encoded string.
+    Json(String),
+
+    /// The assertion is a binary blob with a content type.
+    Binary(String, Vec<u8>),
+}
+
 /// A `DynamicAssertion` is an assertion that has the ability to adjust
 /// its content based on other assertions within the overall [`Manifest`].
 ///
@@ -41,7 +53,7 @@ pub trait DynamicAssertion {
     /// assertion).
     ///
     /// [`Builder`]: crate::Builder
-    fn reserve_size(&self) -> usize;
+    fn reserve_size(&self) -> Result<usize>;
 
     /// Return the final assertion content.
     ///
@@ -61,7 +73,7 @@ pub trait DynamicAssertion {
         label: &str,
         size: Option<usize>,
         claim: &PreliminaryClaim,
-    ) -> Result<Vec<u8>>;
+    ) -> Result<DynamicAssertionContent>;
 }
 
 /// An `AsyncDynamicAssertion` is an assertion that has the ability
@@ -89,7 +101,7 @@ pub trait AsyncDynamicAssertion: Sync {
     /// assertion).
     ///
     /// [`Builder`]: crate::Builder
-    fn reserve_size(&self) -> usize;
+    fn reserve_size(&self) -> Result<usize>;
 
     /// Return the final assertion content.
     ///
@@ -109,7 +121,7 @@ pub trait AsyncDynamicAssertion: Sync {
         label: &str,
         size: Option<usize>,
         claim: &PreliminaryClaim,
-    ) -> Result<Vec<u8>>;
+    ) -> Result<DynamicAssertionContent>;
 }
 
 /// An `AsyncDynamicAssertion` is an assertion that has the ability
@@ -137,7 +149,7 @@ pub trait AsyncDynamicAssertion {
     /// assertion).
     ///
     /// [`Builder`]: crate::Builder
-    fn reserve_size(&self) -> usize;
+    fn reserve_size(&self) -> Result<usize>;
 
     /// Return the final assertion content.
     ///
@@ -157,7 +169,7 @@ pub trait AsyncDynamicAssertion {
         label: &str,
         size: Option<usize>,
         claim: &PreliminaryClaim,
-    ) -> Result<Vec<u8>>;
+    ) -> Result<DynamicAssertionContent>;
 }
 
 /// Describes information from the preliminary C2PA Claim that may

sdk/src/lib.rs

@@ -107,7 +107,9 @@ pub use builder::{Builder, ManifestDefinition};
 pub use c2pa_crypto::raw_signature::SigningAlg;
 pub use callback_signer::{CallbackFunc, CallbackSigner};
 pub use claim_generator_info::ClaimGeneratorInfo;
-pub use dynamic_assertion::{AsyncDynamicAssertion, DynamicAssertion, PreliminaryClaim};
+pub use dynamic_assertion::{
+    AsyncDynamicAssertion, DynamicAssertion, DynamicAssertionContent, PreliminaryClaim,
+};
 pub use error::{Error, Result};
 pub use external_manifest::ManifestPatchCallback;
 pub use hash_utils::{hash_stream_by_alg, HashRange};

sdk/src/store.rs

@@ -44,7 +44,7 @@
     assertions::{
         labels::{self, CLAIM},
         BmffHash, DataBox, DataHash, DataMap, ExclusionsMap, Ingredient, Relationship, SubsetMap,
-        UserCbor,
+        User, UserCbor,
     },
     asset_io::{
         CAIRead, CAIReadWrite, HashBlockObjectType, HashObjectPositions, RemoteRefEmbedType,
@@ -55,7 +55,9 @@
     },
     cose_sign::{cose_sign, cose_sign_async},
     cose_validator::{verify_cose, verify_cose_async},
-    dynamic_assertion::{AsyncDynamicAssertion, DynamicAssertion, PreliminaryClaim},
+    dynamic_assertion::{
+        AsyncDynamicAssertion, DynamicAssertion, DynamicAssertionContent, PreliminaryClaim,
+    },
     error::{Error, Result},
     external_manifest::ManifestPatchCallback,
     hash_utils::{hash_by_alg, vec_compare, verify_by_alg},
@@ -2042,7 +2044,7 @@
         // Two passes since we are accessing two fields in self.
         let mut assertions = Vec::new();
         for da in dyn_assertions.iter() {
-            let reserve_size = da.reserve_size();
+            let reserve_size = da.reserve_size()?;
             let data1 = serde_cbor::ser::to_vec_packed(&vec![0; reserve_size])?;
             let cbor_delta = data1.len() - reserve_size;
             let da_data = serde_cbor::ser::to_vec_packed(&vec![0; reserve_size - cbor_delta])?;
@@ -2080,16 +2082,24 @@
             let label = crate::jumbf::labels::assertion_label_from_uri(&uri.url())
                 .ok_or(Error::BadParam("write_dynamic_assertions".to_string()))?;
 
-            let da_size = da.reserve_size();
+            let da_size = da.reserve_size()?;
             let da_data = if _sync {
                 da.content(&label, Some(da_size), preliminary_claim)?
             } else {
                 da.content(&label, Some(da_size), preliminary_claim).await?
             };
 
-            // TO DO: Add new assertion to preliminary_claim
-            // todo: support for non-CBOR asssertions?
-            final_assertions.push(UserCbor::new(&label, da_data).to_assertion()?);
+            match da_data {
+                DynamicAssertionContent::Cbor(data) => {
+                    final_assertions.push(UserCbor::new(&label, data).to_assertion()?);
+                }
+                DynamicAssertionContent::Json(data) => {
+                    final_assertions.push(User::new(&label, &data).to_assertion()?);
+                }
+                DynamicAssertionContent::Binary(format, data) => {
+                    todo!("Binary dynamic assertions not yet supported");
+                }
+            }
         }
 
         let pc = self.provenance_claim_mut().ok_or(Error::ClaimEncoding)?;
@@ -6137,19 +6147,19 @@
                 "com.mycompany.myassertion".to_string()
             }
 
-            fn reserve_size(&self) -> usize {
+            fn reserve_size(&self) -> Result<usize> {
                 let assertion = TestAssertion {
                     my_tag: "some value I will replace".to_string(),
                 };
-                serde_cbor::to_vec(&assertion).unwrap().len()
+                Ok(serde_cbor::to_vec(&assertion)?.len())
             }
 
             fn content(
                 &self,
                 _label: &str,
                 _size: Option<usize>,
                 claim: &PreliminaryClaim,
-            ) -> Result<Vec<u8>> {
+            ) -> Result<DynamicAssertionContent> {
                 assert!(claim
                     .assertions()
                     .inspect(|a| {
@@ -6161,7 +6171,9 @@
                     my_tag: "some value I will replace".to_string(),
                 };
 
-                Ok(serde_cbor::to_vec(&assertion).unwrap())
+                Ok(DynamicAssertionContent::Cbor(
+                    serde_cbor::to_vec(&assertion).unwrap(),
+                ))
             }
         }
 
@@ -6268,19 +6280,19 @@
                 "com.mycompany.myassertion".to_string()
             }
 
-            fn reserve_size(&self) -> usize {
+            fn reserve_size(&self) -> Result<usize> {
                 let assertion = TestAssertion {
                     my_tag: "some value I will replace".to_string(),
                 };
-                serde_cbor::to_vec(&assertion).unwrap().len()
+                Ok(serde_cbor::to_vec(&assertion)?.len())
             }
 
             async fn content(
                 &self,
                 _label: &str,
                 _size: Option<usize>,
                 claim: &PreliminaryClaim,
-            ) -> Result<Vec<u8>> {
+            ) -> Result<DynamicAssertionContent> {
                 assert!(claim
                     .assertions()
                     .inspect(|a| {
@@ -6292,7 +6304,9 @@
                     my_tag: "some value I will replace".to_string(),
                 };
 
-                Ok(serde_cbor::to_vec(&assertion).unwrap())
+                Ok(DynamicAssertionContent::Cbor(
+                    serde_cbor::to_vec(&assertion).unwrap(),
+                ))
             }
         }