Added wrappers for multi-part digesting functions

Signed-off-by: Jacob Prud'homme <[email protected]>

Author: jacobprudhomme

cryptoki/src/session/digesting.rs

@@ -5,6 +5,7 @@
 use crate::context::Function;
 use crate::error::{Result, Rv};
 use crate::mechanism::Mechanism;
+use crate::object::ObjectHandle;
 use crate::session::Session;
 use cryptoki_sys::*;
 use std::convert::TryInto;
@@ -52,4 +53,76 @@ impl Session {
 
         Ok(digest)
     }
+
+    /// Starts new multi-part digesting operation
+    pub fn digest_initialize(&self, m: &Mechanism) -> Result<()> {
+        let mut mechanism: CK_MECHANISM = m.into();
+
+        unsafe {
+            Rv::from(get_pkcs11!(self.client(), C_DigestInit)(
+                self.handle(),
+                &mut mechanism as CK_MECHANISM_PTR,
+            ))
+            .into_result(Function::DigestInit)?;
+        }
+
+        Ok(())
+    }
+
+    /// Continues an ongoing multi-part digesting operation
+    pub fn digest_update(&self, data: &[u8]) -> Result<()> {
+        unsafe {
+            Rv::from(get_pkcs11!(self.client(), C_DigestUpdate)(
+                self.handle(),
+                data.as_ptr() as *mut u8,
+                data.len().try_into()?,
+            ))
+            .into_result(Function::DigestUpdate)?;
+        }
+
+        Ok(())
+    }
+
+    /// Continues an ongoing multi-part digesting operation, using the value of a secret key as input
+    pub fn digest_key(&self, key: ObjectHandle) -> Result<()> {
+        unsafe {
+            Rv::from(get_pkcs11!(self.client(), C_DigestKey)(
+                self.handle(),
+                key.handle(),
+            ))
+            .into_result(Function::DigestKey)?;
+        }
+
+        Ok(())
+    }
+
+    /// Finalizes ongoing multi-part digest operation
+    pub fn digest_finalize(&self) -> Result<Vec<u8>> {
+        let mut digest_len = 0;
+
+        // Get the output buffer length
+        unsafe {
+            Rv::from(get_pkcs11!(self.client(), C_DigestFinal)(
+                self.handle(),
+                std::ptr::null_mut(),
+                &mut digest_len,
+            ))
+            .into_result(Function::DigestFinal)?;
+        }
+
+        let mut digest = vec![0; digest_len.try_into()?];
+
+        unsafe {
+            Rv::from(get_pkcs11!(self.client(), C_DigestFinal)(
+                self.handle(),
+                digest.as_mut_ptr(),
+                &mut digest_len,
+            ))
+            .into_result(Function::DigestFinal)?;
+        }
+
+        digest.resize(digest_len.try_into()?, 0);
+
+        Ok(digest)
+    }
 }