Secret keys in Podlang (#365)

src/lang/grammar.pest

@@ -60,6 +60,7 @@ anchored_key = { wildcard ~ "[" ~ literal_string ~ "]" }
 // Literal Values (ordered to avoid ambiguity, e.g., string before int)
 literal_value = {
     literal_public_key |
+    literal_secret_key |
     literal_dict |
     literal_set |
     literal_array |
@@ -95,6 +96,11 @@ base58_char = { '1'..'9' | 'A'..'H' | 'J'..'N' | 'P'..'Z' | 'a'..'k' | 'm'..'z'
 base58_string = @{ base58_char+ }
 literal_public_key = { "PublicKey" ~ "(" ~ base58_string ~ ")" }
 
+// SecretKey(...)
+base64_char = { 'a'..'z' | 'A'..'Z' | '0'..'9' | "+" | "/" | "=" }
+base64_string = @{ base64_char+ }
+literal_secret_key = { "SecretKey" ~ "(" ~ base64_string ~ ")" }
+
 // Container Literals (recursive definition using literal_value)
 literal_array = { "[" ~ (literal_value ~ ("," ~ literal_value)*)? ~ "]" }
 literal_set = { "#[" ~ (literal_value ~ ("," ~ literal_value)*)? ~ "]" }

src/lang/mod.rs

@@ -29,6 +29,7 @@ mod tests {
 
     use super::*;
     use crate::{
+        backends::plonky2::primitives::ec::schnorr::SecretKey,
         lang::error::ProcessorError,
         middleware::{
             hash_str, CustomPredicate, CustomPredicateBatch, CustomPredicateRef, Key,
@@ -859,25 +860,32 @@ mod tests {
     #[test]
     fn test_e2e_literals() -> Result<(), LangError> {
         let pk = crate::backends::plonky2::primitives::ec::curve::Point::generator();
-        let pk_b58 = pk.to_string();
         let pod_id = PodId(hash_str("test"));
         let raw = RawValue::from(1);
         let string = "hello";
         let int = 123;
         let bool = true;
+        let sk = SecretKey::new_rand();
 
         let input = format!(
             r#"
             REQUEST(
-                Equal(?A["pk"], PublicKey({}))
-                Equal(?B["pod_id"], {:#})
-                Equal(?C["raw"], Raw({:#}))
-                Equal(?D["string"], "{}")
+                Equal(?A["pk"], {})
+                Equal(?B["pod_id"], {})
+                Equal(?C["raw"], {})
+                Equal(?D["string"], {})
                 Equal(?E["int"], {})
                 Equal(?F["bool"], {})
+                Equal(?G["sk"], {})
             )
         "#,
-            pk_b58, pod_id, raw, string, int, bool
+            Value::from(pk).to_podlang_string(),
+            Value::from(pod_id).to_podlang_string(),
+            Value::from(raw).to_podlang_string(),
+            Value::from(string).to_podlang_string(),
+            Value::from(int).to_podlang_string(),
+            Value::from(bool).to_podlang_string(),
+            Value::from(sk.clone()).to_podlang_string()
         );
         /*
             REQUEST(
@@ -894,7 +902,7 @@ mod tests {
         let processed = parse(&input, &params, &[])?;
         let request_templates = processed.request_templates;
 
-        assert_eq!(request_templates.len(), 6);
+        assert_eq!(request_templates.len(), 7);
 
         let expected_templates = vec![
             StatementTmpl {
@@ -921,6 +929,10 @@ mod tests {
                 pred: Predicate::Native(NativePredicate::Equal),
                 args: vec![sta_ak(("F", 5), "bool"), sta_lit(Value::from(bool))],
             },
+            StatementTmpl {
+                pred: Predicate::Native(NativePredicate::Equal),
+                args: vec![sta_ak(("G", 6), "sk"), sta_lit(Value::from(sk))],
+            },
         ];
 
         assert_eq!(request_templates, expected_templates);

src/lang/pretty_print.rs

@@ -192,6 +192,7 @@ fn fmt_predicate_signature(
 mod tests {
     use super::*;
     use crate::{
+        backends::plonky2::primitives::ec::schnorr::SecretKey,
         lang::parse,
         middleware::{
             CustomPredicate, Key, NativePredicate, Params, Predicate, StatementTmpl,
@@ -492,6 +493,20 @@ mod tests {
         assert_round_trip(input);
     }
 
+    #[test]
+    fn test_round_trip_secret_key() {
+        let sk = SecretKey::new_rand();
+        let input = format!(
+            r#"
+            secret_key_test(Pod) = AND(
+                Equal(?Pod["sk"], {})
+            )
+            "#,
+            Value::from(sk.clone()).to_podlang_string()
+        );
+        assert_round_trip(&input);
+    }
+
     #[test]
     fn test_pretty_print_demonstration() {
         let input = r#"

src/lang/processor.rs

@@ -8,9 +8,12 @@ use plonky2::field::types::Field;
 
 use super::error::ProcessorError;
 use crate::{
-    backends::plonky2::primitives::ec::curve::Point,
+    backends::plonky2::{
+        deserialize_bytes,
+        primitives::ec::{curve::Point, schnorr::SecretKey},
+    },
     frontend::{BuilderArg, CustomPredicateBatchBuilder, StatementTmplBuilder},
-    lang::parser::Rule,
+    lang::Rule,
     middleware::{
         self, CustomPredicateBatch, CustomPredicateRef, Key, NativePredicate, Params, Predicate,
         StatementTmpl, StatementTmplArg, Value, Wildcard, F, VALUE_SIZE,
@@ -795,6 +798,25 @@ fn process_literal_value(
                     })?;
             Ok(Value::from(middleware_dict))
         }
+        Rule::literal_secret_key => {
+            let sk_str_pair = inner_lit.clone().into_inner().next().unwrap();
+            let sk_base64 = sk_str_pair.as_str();
+            let bytes = deserialize_bytes(sk_base64).map_err(|_e| {
+                ProcessorError::InvalidLiteralFormat {
+                    kind: "SecretKey".to_string(),
+                    value: sk_base64.to_string(),
+                    span: Some(get_span(&inner_lit)),
+                }
+            })?;
+            let secret_key = SecretKey::from_bytes(&bytes).map_err(|_e| {
+                ProcessorError::InvalidLiteralFormat {
+                    kind: "SecretKey".to_string(),
+                    value: sk_base64.to_string(),
+                    span: Some(get_span(&inner_lit)),
+                }
+            })?;
+            Ok(Value::from(secret_key))
+        }
         _ => unreachable!("Unexpected rule: {:?}", inner_lit.as_rule()),
     }
 }